Attachment 422371 Details for Bug 222607 – Patch

[patch] Patch

bug-222607-20210305163702.patch (text/plain), 89.76 KB, created by Imanol Fernandez on 2021-03-05 07:37:03 PST

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Creator: Imanol Fernandez

Created: 2021-03-05 07:37:03 PST

Size: 89.76 KB

patch

obsolete

>Subversion Revision: 273964
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index 899949545f639a15e5bd799da2253d8038cb775f..a111ca9916425937a934b77e59d8588312f3ccae 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,116 @@
>+2021-03-02  Imanol Fernandez  <ifernandez@igalia.com>
>+
>+        Implement WebXR Opaque Framebuffer
>+        https://bugs.webkit.org/show_bug.cgi?id=222607
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        This patch adds a base XR layers API which is initially used by WebXRWebGLLayer, but
>+        with the goal of supporting more types of layers in the future (see WebXR Layers spec).
>+
>+        Layers are connected to WebGL by using shared textures. In the case of WebXRWebGLLayer
>+        it creates an Opaque Framebuffer that renders to the shared texture. XR runtimes supporting
>+        double or triple buffering can send different shared textures each frame in the FrameData struct.
>+        The texture for the current frame is attached in WebXRLayer::startFrame and prepared to send it back to the
>+        VR compositor in WebXRLayer::endFrame().
>+
>+        Tested by the WebXR WPT tests.
>+
>+        * Modules/webxr/WebXRLayer.h: add startFrame and endFrame pure virtual methods.
>+        * Modules/webxr/WebXRSession.cpp:
>+        (WebCore::WebXRSession::onFrame): do not call RAFs if frameData.shouldRender is false.
>+        * Modules/webxr/WebXRSession.h: add device getter.
>+
>+        * Modules/webxr/WebXRSystem.cpp:
>+        (WebCore::WebXRSystem::DummyInlineDevice::requestFrame): always enable frameData.shouldRender flag.
>+        * Modules/webxr/WebXRSystem.h: Override new virtual functions.
>+        * Modules/webxr/WebXRViewport.h:
>+        (WebCore::WebXRViewport::rect const): Add helper method.
>+
>+        * Modules/webxr/WebXRWebGLLayer.cpp: Refactor resource initialization to create method.
>+        (WebCore::WebXRWebGLLayer::create):
>+        (WebCore::WebXRWebGLLayer::WebXRWebGLLayer):
>+        (WebCore::m_isCompositionEnabled):
>+        (WebCore::WebXRWebGLLayer::framebuffer const):
>+        (WebCore::WebXRWebGLLayer::framebufferWidth const):
>+        (WebCore::WebXRWebGLLayer::framebufferHeight const):
>+        (WebCore::WebXRWebGLLayer::startFrame): Prepare Opaque Framebuffer for the start of next frame.
>+        (WebCore::WebXRWebGLLayer::endFrame): Prepare Opaque Framebuffer for VR compositor submitFrame.
>+        (WebCore::WebXRWebGLLayer::canvasResized): Move method
>+
>+        (WebCore::WebXROpaqueFramebuffer::create): Implement class to manage WebXR Opaque framebuffer.
>+        (WebCore::WebXROpaqueFramebuffer::WebXROpaqueFramebuffer):
>+        (WebCore::WebXROpaqueFramebuffer::~WebXROpaqueFramebuffer):
>+        (WebCore::WebXROpaqueFramebuffer::startFrame): Attach shared texture for the current frame.
>+        (WebCore::WebXROpaqueFramebuffer::endFrame): Flush and resolve multisampling if required.
>+        (WebCore::WebXROpaqueFramebuffer::setupFramebuffer): Allocate the Opaque framebuffer with requested attributes.
>+
>+        * Modules/webxr/WebXRWebGLLayer.h:  Add WebXROpaqueFramebuffer and handle members.
>+        (WebCore::WebXROpaqueFramebuffer::handle const):
>+        (WebCore::WebXROpaqueFramebuffer::framebuffer const):
>+        (WebCore::WebXROpaqueFramebuffer::width const):
>+        (WebCore::WebXROpaqueFramebuffer::height const):
>+
>+        * Sources.txt: Add OpenXRLayer.cpp and OpenXRSwapchain.cpp.
>+
>+        * html/canvas/WebGL2RenderingContext.cpp:
>+        (WebCore::WebGL2RenderingContext::getFramebufferAttachmentParameter): handle Opaque Framebuffers.
>+
>+        * html/canvas/WebGLFramebuffer.cpp: Add members and methods required for Opaque Framebuffers.
>+        (WebCore::WebGLFramebuffer::createOpaque):
>+        (WebCore::WebGLFramebuffer::checkStatus const):
>+        * html/canvas/WebGLFramebuffer.h:
>+
>+        * html/canvas/WebGLRenderingContext.cpp:
>+        (WebCore::WebGLRenderingContext::getFramebufferAttachmentParameter): handle Opaque Framebuffers.
>+
>+        * html/canvas/WebGLRenderingContextBase.cpp: handle Opaque Framebuffers.
>+        (WebCore::WebGLRenderingContextBase::deleteFramebuffer):
>+        (WebCore::WebGLRenderingContextBase::framebufferRenderbuffer):
>+        (WebCore::WebGLRenderingContextBase::framebufferTexture2D):
>+
>+        * platform/xr/PlatformXR.h: Add method to submitFrame.
>+        (PlatformXR::Device::submitFrame):
>+
>+        * platform/xr/openxr/OpenXRLayer.cpp: Add class to manage OpenXR layers.
>+        (PlatformXR::OpenXRLayer::OpenXRLayer):
>+        (PlatformXR::OpenXRLayerProjection::create):
>+        (PlatformXR::OpenXRLayerProjection::OpenXRLayerProjection):
>+        (PlatformXR::OpenXRLayerProjection::startFrame):
>+        * platform/xr/openxr/OpenXRLayer.h: Added.
>+        (PlatformXR::OpenXRLayer::handle):
>+
>+        * platform/xr/openxr/OpenXRSwapchain.cpp: Add class to manage OpenXR swapchains
>+        (PlatformXR::OpenXRSwapchain::create):
>+        (PlatformXR::OpenXRSwapchain::OpenXRSwapchain):
>+        (PlatformXR::OpenXRSwapchain::~OpenXRSwapchain):
>+        (PlatformXR::OpenXRSwapchain::acquireImage):
>+        (PlatformXR::OpenXRSwapchain::releaseImage):
>+        * platform/xr/openxr/OpenXRSwapchain.h: Added.
>+
>+        * platform/xr/openxr/OpenXRUtils.h: Add helper log function
>+        (PlatformXR::xrViewToPose): Use fabs instead of negation
>+
>+        * platform/xr/openxr/PlatformXROpenXR.cpp:
>+        (PlatformXR::OpenXRDevice::initializeTrackingAndRendering): create GraphicsContextGL for texture sharing.
>+        (PlatformXR::OpenXRDevice::requestFrame): Prepare and fill layers if shouldRender is true.
>+        (PlatformXR::OpenXRDevice::submitFrame): Implement submit layers to OpenXR
>+        (PlatformXR::OpenXRDevice::createLayerProjection): Implement layer creation method
>+        (PlatformXR::OpenXRDevice::deleteLayer): Implement layer deallocation
>+        (PlatformXR::OpenXRDevice::collectEnabledFeatures const):
>+        (PlatformXR::OpenXRDevice::resetSession): Deallocate layers and graphics context.
>+
>+        * platform/xr/openxr/PlatformXROpenXR.h: Add Layers API
>+
>+        * testing/WebFakeXRDevice.cpp:
>+        (WebCore::SimulatedXRDevice::recommendedResolution): Increase size to avoid platform minimum FBO size errors
>+        (WebCore::SimulatedXRDevice::initializeTrackingAndRendering): Create graphics context
>+        (WebCore::SimulatedXRDevice::shutDownTrackingAndRendering): Release graphics context
>+        (WebCore::SimulatedXRDevice::frameTimerFired): set up layers in frame data
>+        (WebCore::SimulatedXRDevice::createLayerProjection): creates a texture for a layer.
>+        (WebCore::SimulatedXRDevice::deleteLayer): releases the associated texture to a layer
>+        * testing/WebFakeXRDevice.h:
>+
> 2021-03-05  Chris Lord  <clord@igalia.com>
> 
>         Allow CSS font-styling for canvas without RenderStyle
>diff --git a/Source/WebCore/Modules/webxr/WebXRLayer.h b/Source/WebCore/Modules/webxr/WebXRLayer.h
>index 003f56c7d441e764ca63669526880f762953870d..dfc13830c3fc9ffe0960723348f1d7b81a82ec05 100644
>--- a/Source/WebCore/Modules/webxr/WebXRLayer.h
>+++ b/Source/WebCore/Modules/webxr/WebXRLayer.h
>@@ -29,6 +29,7 @@
> 
> #include "ContextDestructionObserver.h"
> #include "EventTarget.h"
>+#include "PlatformXR.h"
> #include <wtf/IsoMalloc.h>
> #include <wtf/RefCounted.h>
> 
>@@ -44,6 +45,9 @@ public:
>     using RefCounted<WebXRLayer>::ref;
>     using RefCounted<WebXRLayer>::deref;
> 
>+    virtual void startFrame(const PlatformXR::Device::FrameData&) = 0;
>+    virtual PlatformXR::Device::Layer endFrame() = 0;
>+
> protected:
>     explicit WebXRLayer(ScriptExecutionContext*);
> 
>diff --git a/Source/WebCore/Modules/webxr/WebXRSession.cpp b/Source/WebCore/Modules/webxr/WebXRSession.cpp
>index dd1eccd01f503a28ac9dc79478149bbeb81d2990..c9fe09346bde9f2504e1283deb7b435686951c7b 100644
>--- a/Source/WebCore/Modules/webxr/WebXRSession.cpp
>+++ b/Source/WebCore/Modules/webxr/WebXRSession.cpp
>@@ -513,7 +513,11 @@ void WebXRSession::onFrame(PlatformXR::Device::FrameData&& frameData)
>             applyPendingRenderState();
> 
>         // 6. If the frame should be rendered for session:
>-        if (frameShouldBeRendered()) {
>+        if (frameShouldBeRendered() && m_frameData.shouldRender) {
>+            // Prepare all layers for render
>+            if (m_mode == XRSessionMode::ImmersiveVr && m_activeRenderState->baseLayer())
>+                m_activeRenderState->baseLayer()->startFrame(m_frameData);
>+
>             // 6.1.Set sessionâs list of currently running animation frame callbacks to be sessionâs list of animation frame callbacks.
>             // 6.2.Set sessionâs list of animation frame callbacks to the empty list.
>             auto callbacks = m_callbacks;
>@@ -544,10 +548,18 @@ void WebXRSession::onFrame(PlatformXR::Device::FrameData&& frameData)
>             // If the session is ended, m_animationFrame->setActive false is set in shutdown().
>             frame->setActive(false);
> 
>-            if (!m_callbacks.isEmpty())
>-                requestFrame();
>+
>+            // Submit current frame layers to the device.
>+            Vector<PlatformXR::Device::Layer> frameLayers;
>+            if (m_mode == XRSessionMode::ImmersiveVr && m_activeRenderState->baseLayer())
>+                frameLayers.append(m_activeRenderState->baseLayer()->endFrame());
>+
>+            m_device->submitFrame(WTFMove(frameLayers));
>         }
> 
>+        if (!m_callbacks.isEmpty())
>+            requestFrame();
>+
>     });
> }
> 
>diff --git a/Source/WebCore/Modules/webxr/WebXRSession.h b/Source/WebCore/Modules/webxr/WebXRSession.h
>index 85cc2551c2c83e9861a547e2adf5ddf429a7535f..50459772667f738f32e5ef82d7ea7ed6324962e6 100644
>--- a/Source/WebCore/Modules/webxr/WebXRSession.h
>+++ b/Source/WebCore/Modules/webxr/WebXRSession.h
>@@ -72,6 +72,7 @@ public:
>     XRVisibilityState visibilityState() const;
>     const WebXRRenderState& renderState() const;
>     const WebXRInputSourceArray& inputSources() const;
>+    PlatformXR::Device* device() const { return m_device.get(); }
> 
>     ExceptionOr<void> updateRenderState(const XRRenderStateInit&);
>     void requestReferenceSpace(XRReferenceSpaceType, RequestReferenceSpacePromise&&);
>diff --git a/Source/WebCore/Modules/webxr/WebXRSystem.cpp b/Source/WebCore/Modules/webxr/WebXRSystem.cpp
>index f6fba3d9a788616035d3608b687b25678762430a..2ff150358655a4149c58f1a85f853c3254acb63c 100644
>--- a/Source/WebCore/Modules/webxr/WebXRSystem.cpp
>+++ b/Source/WebCore/Modules/webxr/WebXRSystem.cpp
>@@ -524,6 +524,7 @@ void WebXRSystem::DummyInlineDevice::requestFrame(PlatformXR::Device::RequestFra
>         PlatformXR::Device::FrameData data;
>         data.isTrackingValid = true;
>         data.isPositionValid = true;
>+        data.shouldRender = true;
>         data.views.append({ });
>         callback(WTFMove(data));
>     });
>diff --git a/Source/WebCore/Modules/webxr/WebXRSystem.h b/Source/WebCore/Modules/webxr/WebXRSystem.h
>index 1024d0f5a4f3c1f6b41adf7f96bd83cc384ad081..4c5cbebe87544ed014ab25c7aeac4fe0851dac86 100644
>--- a/Source/WebCore/Modules/webxr/WebXRSystem.h
>+++ b/Source/WebCore/Modules/webxr/WebXRSystem.h
>@@ -115,6 +115,8 @@ private:
> 
>         void requestFrame(PlatformXR::Device::RequestFrameCallback&&) final;
>         Vector<Device::ViewData> views(XRSessionMode) const final;
>+        Optional<PlatformXR::LayerHandle> createLayerProjection(uint32_t, uint32_t, bool) final { return WTF::nullopt; }
>+        void deleteLayer(PlatformXR::LayerHandle) final { }
>     };
>     DummyInlineDevice m_defaultInlineDevice;
> 
>diff --git a/Source/WebCore/Modules/webxr/WebXRViewport.h b/Source/WebCore/Modules/webxr/WebXRViewport.h
>index 0a5fecb2e359f2c41ece40a7b310a8d7108ef198..5627e96456bb79bfe1b8d2681413ab013f7b3d33 100644
>--- a/Source/WebCore/Modules/webxr/WebXRViewport.h
>+++ b/Source/WebCore/Modules/webxr/WebXRViewport.h
>@@ -43,6 +43,7 @@ public:
>     int y() const { return m_viewport.y(); }
>     int width() const { return m_viewport.width(); }
>     int height() const { return m_viewport.height(); }
>+    IntRect rect() { return m_viewport; }
> 
>     void updateViewport(const IntRect& viewport) { m_viewport = viewport; }
> 
>diff --git a/Source/WebCore/Modules/webxr/WebXRWebGLLayer.cpp b/Source/WebCore/Modules/webxr/WebXRWebGLLayer.cpp
>index c8d42e54433acdf2cd23b6854f0550e1ab5c402a..c68fe14c400824f07355963f4baebd61957b1226 100644
>--- a/Source/WebCore/Modules/webxr/WebXRWebGLLayer.cpp
>+++ b/Source/WebCore/Modules/webxr/WebXRWebGLLayer.cpp
>@@ -28,9 +28,13 @@
> 
> #if ENABLE(WEBXR)
> 
>+#include "ExtensionsGLOpenGLCommon.h"
>+#include "ExtensionsGLOpenGLES.h"
>+#include "GraphicsContextGL.h"
> #include "HTMLCanvasElement.h"
> #include "IntSize.h"
> #include "OffscreenCanvas.h"
>+#include "TemporaryOpenGLSetting.h"
> #include "WebGLFramebuffer.h"
> #include "WebGLRenderingContext.h"
> #if ENABLE(WEBGL2)
>@@ -47,8 +51,52 @@
> 
> namespace WebCore {
> 
>+using GL = GraphicsContextGL;
>+
> WTF_MAKE_ISO_ALLOCATED_IMPL(WebXRWebGLLayer);
> 
>+// Arbitrary value for minimum framebuffer scaling.
>+// Below this threshold the resulting framebuffer would be too small to see.
>+static constexpr double MinFramebufferScalingFactor = 0.2;
>+
>+static ExceptionOr<std::unique_ptr<WebXROpaqueFramebuffer>> createOpaqueFramebuffer(WebXRSession& session, WebGLRenderingContextBase& context, const XRWebGLLayerInit& init)
>+{
>+    auto device = session.device();
>+    if (!device)
>+        return Exception { OperationError };
>+
>+    // 9.1. Initialize layerâs antialias to layerInitâs antialias value.
>+    // 9.2. Let framebufferSize be the recommended WebGL framebuffer resolution multiplied by layerInit's framebufferScaleFactor.
>+
>+    float scaleFactor = std::clamp(init.framebufferScaleFactor, MinFramebufferScalingFactor, device->maxFramebufferScalingFactor());
>+
>+    IntSize recommendedSize = session.recommendedWebGLFramebufferResolution();
>+    auto width = static_cast<uint32_t>(std::ceil(2 * recommendedSize.width() * scaleFactor));
>+    auto height = static_cast<uint32_t>(std::ceil(recommendedSize.height() * scaleFactor));
>+
>+    // 9.3. Initialize layerâs framebuffer to a new opaque framebuffer with the dimensions framebufferSize
>+    //      created with context, session initialized to session, and layerInitâs depth, stencil, and alpha values.
>+    // 9.4. Allocate and initialize resources compatible with sessionâs XR device, including GPU accessible memory buffers,
>+    //      as required to support the compositing of layer.
>+    // 9.5. If layerâs resources were unable to be created for any reason, throw an OperationError and abort these steps.
>+    auto layerHandle = device->createLayerProjection(width, height, init.alpha);
>+    if (!layerHandle)
>+        return Exception { OperationError };
>+
>+    WebXROpaqueFramebuffer::Attributes attributes {
>+        .alpha = init.alpha,
>+        .antialias = init.antialias,
>+        .depth = init.depth,
>+        .stencil = init.stencil
>+    };
>+
>+    auto framebuffer = WebXROpaqueFramebuffer::create(*layerHandle, context, WTFMove(attributes), width, height);
>+    if (!framebuffer)
>+        return Exception { OperationError };
>+    
>+    return framebuffer;
>+}
>+
> // https://immersive-web.github.io/webxr/#dom-xrwebgllayer-xrwebgllayer
> ExceptionOr<Ref<WebXRWebGLLayer>> WebXRWebGLLayer::create(Ref<WebXRSession>&& session, WebXRRenderingContext&& context, const XRWebGLLayerInit& init)
> {
>@@ -74,19 +122,34 @@ ExceptionOr<Ref<WebXRWebGLLayer>> WebXRWebGLLayer::create(Ref<WebXRSession>&& se
>             // 5. Initialize layerâs context to context. (see constructor)
>             // 6. Initialize layerâs session to session. (see constructor)
>             // 7. Initialize layerâs ignoreDepthValues as follows. (see constructor)
>-            // 8. Initialize layerâs composition disabled boolean as follows. (see constructor)
>-            // 9. (see constructor except for the resources initialization step which is handled in the if block below)
>-            auto layer = adoptRef(*new WebXRWebGLLayer(WTFMove(session), WTFMove(context), init));
>-
>-            if (layer->m_isCompositionEnabled) {
>-                // 9.4. Allocate and initialize resources compatible with sessionâs XR device, including GPU accessible memory buffers,
>-                //      as required to support the compositing of layer.
>-                // 9.5. If layerâs resources were unable to be created for any reason, throw an OperationError and abort these steps.
>-                // TODO: Initialize layer's resources or issue an OperationError.
>+            //   7.1 If layerInitâs ignoreDepthValues value is false and the XR Compositor will make use of depth values,
>+            //       Initialize layerâs ignoreDepthValues to false.
>+            //   7.2. Else Initialize layerâs ignoreDepthValues to true
>+            // TODO: ask XR compositor for depth value usages support
>+            bool ignoreDepthValues = true;
>+            // 8. Initialize layerâs composition disabled boolean as follows.
>+            //    If session is an inline session -> Initialize layer's composition disabled to true
>+            //    Otherwise -> Initialize layer's composition disabled boolean to false
>+            bool isCompositionEnabled = session->mode() != XRSessionMode::Inline;
>+            bool antialias = false;
>+            std::unique_ptr<WebXROpaqueFramebuffer> framebuffer;
>+
>+            // 9. If layer's composition enabled boolean is true: 
>+            if (isCompositionEnabled) {
>+                auto createResult = createOpaqueFramebuffer(session.get(), *baseContext, init);
>+                if (createResult.hasException())
>+                    return createResult.releaseException();
>+                framebuffer = createResult.releaseReturnValue();
>+            } else {
>+                // Otherwise
>+                // 9.1. Initialize layerâs antialias to layerâs context's actual context parameters antialias value.
>+                if (auto attributes = baseContext->getContextAttributes())
>+                    antialias = attributes->antialias;
>+                // 9.2 Initialize layer's framebuffer to null.
>             }
> 
>             // 10. Return layer.
>-            return layer;
>+            return adoptRef(*new WebXRWebGLLayer(WTFMove(session), WTFMove(context), WTFMove(framebuffer), antialias, ignoreDepthValues, isCompositionEnabled));
>         },
>         [](WTF::Monostate) {
>             ASSERT_NOT_REACHED();
>@@ -95,63 +158,18 @@ ExceptionOr<Ref<WebXRWebGLLayer>> WebXRWebGLLayer::create(Ref<WebXRSession>&& se
>     );
> }
> 
>-WebXRWebGLLayer::WebXRWebGLLayer(Ref<WebXRSession>&& session, WebXRRenderingContext&& context, const XRWebGLLayerInit& init)
>+WebXRWebGLLayer::WebXRWebGLLayer(Ref<WebXRSession>&& session, WebXRRenderingContext&& context, std::unique_ptr<WebXROpaqueFramebuffer>&& framebuffer,
>+    bool antialias, bool ignoreDepthValues, bool isCompositionEnabled)
>     : WebXRLayer(session->scriptExecutionContext())
>     , m_session(WTFMove(session))
>     , m_context(WTFMove(context))
>     , m_leftViewportData({ WebXRViewport::create({ }) })
>     , m_rightViewportData({ WebXRViewport::create({ }) })
>+    , m_framebuffer(WTFMove(framebuffer))
>+    , m_antialias(antialias)
>+    , m_ignoreDepthValues(ignoreDepthValues)
>+    , m_isCompositionEnabled(isCompositionEnabled)
> {
>-    // 7. Initialize layerâs ignoreDepthValues as follows:
>-    //   7.1 If layerInitâs ignoreDepthValues value is false and the XR Compositor will make use of depth values,
>-    //       Initialize layerâs ignoreDepthValues to false.
>-    //   7.2. Else Initialize layerâs ignoreDepthValues to true
>-    // TODO: ask XR compositor for depth value usages
>-    m_ignoreDepthValues = init.ignoreDepthValues;
>-
>-    // 8. Initialize layer's composition disabled boolean as follows:
>-    //  If session is an inline session -> Initialize layer's composition disabled to true
>-    //  Otherwise -> Initialize layer's composition disabled boolean to false
>-    m_isCompositionEnabled = m_session->mode() != XRSessionMode::Inline;
>-
>-    // 9. If layerâs composition disabled boolean is false:
>-    if (m_isCompositionEnabled) {
>-        //  1. Initialize layerâs antialias to layerInitâs antialias value.
>-        m_antialias = init.antialias;
>-
>-        //  2. Let framebufferSize be the recommended WebGL framebuffer resolution multiplied by layerInit's framebufferScaleFactor.
>-        IntSize recommendedSize = m_session->recommendedWebGLFramebufferResolution();
>-        m_framebuffer.width = recommendedSize.width() * init.framebufferScaleFactor;
>-        m_framebuffer.height = recommendedSize.height() * init.framebufferScaleFactor;
>-
>-        //  3. Initialize layerâs framebuffer to a new opaque framebuffer with the dimensions framebufferSize
>-        //       created with context, session initialized to session, and layerInitâs depth, stencil, and alpha values.
>-        // For steps 4 & 5 see the create() method as resources initialization is handled outside the constructor as it might trigger
>-        // an OperationError.
>-        // FIXME: create a proper opaque framebuffer.
>-        m_framebuffer.object = WTF::switchOn(m_context,
>-            [](const RefPtr<WebGLRenderingContextBase>& baseContext)
>-            {
>-                return WebGLFramebuffer::create(*baseContext);
>-            }
>-        );
>-    } else {
>-        // 1. Initialize layerâs antialias to layerâs context's actual context parameters antialias value.
>-        m_antialias = WTF::switchOn(m_context,
>-            [](const RefPtr<WebGLRenderingContextBase>& context)
>-            {
>-                if (auto attributes = context->getContextAttributes())
>-                    return attributes.value().antialias;
>-                return false;
>-            }
>-        );
>-        // 2. Initialize layerâs framebuffer to null.
>-        m_framebuffer.object = nullptr;
>-    }
>-
>-    auto canvasElement = canvas();
>-    if (canvasElement)
>-        canvasElement->addObserver(*this);
> }
> 
> WebXRWebGLLayer::~WebXRWebGLLayer()
>@@ -159,6 +177,11 @@ WebXRWebGLLayer::~WebXRWebGLLayer()
>     auto canvasElement = canvas();
>     if (canvasElement)
>         canvasElement->removeObserver(*this);
>+    if (m_framebuffer) {
>+        auto device = m_session->device();
>+        if (device)
>+            device->deleteLayer(m_framebuffer->handle());
>+    }
> }
> 
> bool WebXRWebGLLayer::antialias() const
>@@ -171,15 +194,15 @@ bool WebXRWebGLLayer::ignoreDepthValues() const
>     return m_ignoreDepthValues;
> }
> 
>-WebGLFramebuffer* WebXRWebGLLayer::framebuffer() const
>+const WebGLFramebuffer* WebXRWebGLLayer::framebuffer() const
> {
>-    return m_framebuffer.object.get();
>+    return m_framebuffer ? &m_framebuffer->framebuffer() : nullptr;
> }
> 
> unsigned WebXRWebGLLayer::framebufferWidth() const
> {
>-    if (m_framebuffer.object)
>-        return m_framebuffer.width;
>+    if (m_framebuffer)
>+        return m_framebuffer->width();
>     return WTF::switchOn(m_context,
>         [&](const RefPtr<WebGLRenderingContextBase>& baseContext) {
>             return baseContext->drawingBufferWidth();
>@@ -188,8 +211,8 @@ unsigned WebXRWebGLLayer::framebufferWidth() const
> 
> unsigned WebXRWebGLLayer::framebufferHeight() const
> {
>-    if (m_framebuffer.object)
>-        return m_framebuffer.height;
>+    if (m_framebuffer)
>+        return m_framebuffer->height();
>     return WTF::switchOn(m_context,
>         [&](const RefPtr<WebGLRenderingContextBase>& baseContext) {
>             return baseContext->drawingBufferHeight();
>@@ -256,6 +279,39 @@ HTMLCanvasElement* WebXRWebGLLayer::canvas() const
>     });
> }
> 
>+
>+void WebXRWebGLLayer::startFrame(const PlatformXR::Device::FrameData& data)
>+{
>+    ASSERT(m_framebuffer);
>+
>+    auto it = data.layers.find(m_framebuffer->handle());
>+    if (it == data.layers.end()) {
>+        // For some reason the device didn't provide a texture for this frame.
>+        // The frame is ignored and the device can recover the texture in future frames;
>+        return;
>+    }
>+
>+    m_framebuffer->startFrame(it->value);
>+}
>+
>+PlatformXR::Device::Layer WebXRWebGLLayer::endFrame()
>+{
>+    ASSERT(m_framebuffer);
>+    m_framebuffer->endFrame();
>+
>+    Vector<PlatformXR::Device::LayerView> views = {
>+        { PlatformXR::Eye::Left, m_leftViewportData.viewport->rect() },
>+        { PlatformXR::Eye::Right, m_rightViewportData.viewport->rect() }
>+    };
>+
>+    return PlatformXR::Device::Layer { .handle = m_framebuffer->handle(), .visible = true, .views = WTFMove(views) };
>+}
>+
>+void WebXRWebGLLayer::canvasResized(CanvasBase&)
>+{
>+    m_viewportsDirty = true;
>+}
>+
> // https://immersive-web.github.io/webxr/#xrview-obtain-a-scaled-viewport
> void WebXRWebGLLayer::computeViewports()
> {
>@@ -283,9 +339,245 @@ void WebXRWebGLLayer::computeViewports()
>     m_viewportsDirty = false;
> }
> 
>-void WebXRWebGLLayer::canvasResized(CanvasBase&)
>+// WebXROpaqueFramebuffer
>+
>+std::unique_ptr<WebXROpaqueFramebuffer> WebXROpaqueFramebuffer::create(PlatformXR::LayerHandle handle, WebGLRenderingContextBase& context, Attributes&& attributes, uint32_t width, uint32_t height)
> {
>-    m_viewportsDirty = true;
>+    auto framebuffer = WebGLFramebuffer::createOpaque(context);
>+    auto opaque = std::unique_ptr<WebXROpaqueFramebuffer>(new WebXROpaqueFramebuffer(handle, WTFMove(framebuffer), context, WTFMove(attributes), width, height));
>+    if (!opaque->setupFramebuffer())
>+        return nullptr;
>+    return opaque;
>+}
>+
>+WebXROpaqueFramebuffer::WebXROpaqueFramebuffer(PlatformXR::LayerHandle handle, Ref<WebGLFramebuffer>&& framebuffer, WebGLRenderingContextBase& context, Attributes&& attributes, uint32_t width, uint32_t height)
>+    : m_handle(handle)
>+    , m_framebuffer(WTFMove(framebuffer))
>+    , m_context(context)
>+    , m_attributes(WTFMove(attributes))
>+    , m_width(width)
>+    , m_height(height)
>+{
>+}
>+
>+WebXROpaqueFramebuffer::~WebXROpaqueFramebuffer()
>+{
>+    auto gl = m_context.graphicsContextGL();
>+    if (gl) {
>+        if (m_stencilBuffer)
>+            gl->deleteRenderbuffer(m_stencilBuffer);
>+        if (m_depthStencilBuffer)
>+            gl->deleteRenderbuffer(m_depthStencilBuffer);
>+        if (m_multisampleColorBuffer)
>+            gl->deleteRenderbuffer(m_multisampleColorBuffer);
>+        if (m_resolvedFBO)
>+            gl->deleteFramebuffer(m_resolvedFBO);
>+    }
>+    m_context.deleteFramebuffer(m_framebuffer.ptr());
>+}
>+
>+void WebXROpaqueFramebuffer::startFrame(const PlatformXR::Device::FrameData::LayerData& data)
>+{
>+    m_opaqueTexture = data.opaqueTexture;
>+    if (!m_context.graphicsContextGL())
>+        return;
>+    auto& gl = *m_context.graphicsContextGL();
>+
>+    m_framebuffer->setOpaqueActive(true);
>+
>+    GCGLint boundFBO { 0 };
>+
>+    gl.getIntegerv(GL::FRAMEBUFFER_BINDING, makeGCGLSpan(&boundFBO, 1));
>+    auto scopedFBOs = makeScopeExit([&gl, boundFBO]() {
>+        gl.bindFramebuffer(GL::FRAMEBUFFER, boundFBO);
>+    });
>+
>+    gl.bindFramebuffer(GL::FRAMEBUFFER, m_framebuffer->object());
>+    // https://immersive-web.github.io/webxr/#opaque-framebuffer
>+    // The buffers attached to an opaque framebuffer MUST be cleared to the values in the table below when first created,
>+    // or prior to the processing of each XR animation frame.
>+    std::array<const GCGLenum, 3> attachments = { GL::COLOR_ATTACHMENT0, GL::STENCIL_ATTACHMENT, GL::DEPTH_ATTACHMENT };
>+    gl.invalidateFramebuffer(GL::FRAMEBUFFER, makeGCGLSpan(attachments.data(), attachments.size()));
>+
>+#if USE(OPENGL_ES)
>+    auto& extensions = reinterpret_cast<ExtensionsGLOpenGLES&>(gl.getExtensions());
>+    if (m_attributes.antialias && extensions.isImagination()) {
>+        extensions.framebufferTexture2DMultisampleIMG(GL::FRAMEBUFFER, GL::COLOR_ATTACHMENT0, GL::TEXTURE_2D, m_opaqueTexture, 0, m_sampleCount);
>+        return;
>+    }
>+#endif
>+
>+    if (!m_multisampleColorBuffer)
>+        gl.framebufferTexture2D(GL::FRAMEBUFFER, GL::COLOR_ATTACHMENT0, GL::TEXTURE_2D, m_opaqueTexture, 0);
>+}
>+
>+void WebXROpaqueFramebuffer::endFrame()
>+{
>+    m_framebuffer->setOpaqueActive(false);
>+
>+    if (!m_context.graphicsContextGL())
>+        return;
>+    auto& gl = *m_context.graphicsContextGL();
>+
>+    if (m_multisampleColorBuffer) {
>+        TemporaryOpenGLSetting scopedScissor(GL::SCISSOR_TEST, 0);
>+        TemporaryOpenGLSetting scopedDither(GL::DITHER, 0);
>+        TemporaryOpenGLSetting scopedDepth(GL::DEPTH_TEST, 0);
>+        TemporaryOpenGLSetting scopedStencil(GL::STENCIL_TEST, 0);
>+
>+        GCGLint boundReadFBO { 0 };
>+        GCGLint boundDrawFBO { 0 };
>+        gl.getIntegerv(GL::READ_FRAMEBUFFER_BINDING, makeGCGLSpan(&boundReadFBO, 1));
>+        gl.getIntegerv(GL::DRAW_FRAMEBUFFER_BINDING, makeGCGLSpan(&boundDrawFBO, 1));
>+
>+        auto scopedFBOs = makeScopeExit([&gl, boundReadFBO, boundDrawFBO]() {
>+            gl.bindFramebuffer(GL::READ_FRAMEBUFFER, boundReadFBO);
>+            gl.bindFramebuffer(GL::DRAW_FRAMEBUFFER, boundDrawFBO);
>+        });
>+
>+        gl.bindFramebuffer(GL::DRAW_FRAMEBUFFER, m_resolvedFBO);
>+        gl.framebufferTexture2D(GL::FRAMEBUFFER, GL::COLOR_ATTACHMENT0, GL::TEXTURE_2D, m_opaqueTexture, 0);
>+
>+        // Resolve multisample framebuffer
>+        gl.bindFramebuffer(GL::READ_FRAMEBUFFER, m_framebuffer->object());
>+        gl.blitFramebuffer(0, 0, m_width, m_height, 0, 0, m_width, m_height, GL::COLOR_BUFFER_BIT, GL::LINEAR);
>+    }
>+    
>+    gl.flush();
>+}
>+
>+bool WebXROpaqueFramebuffer::setupFramebuffer()
>+{
>+    if (!m_context.graphicsContextGL())
>+        return false;
>+    auto& gl = *m_context.graphicsContextGL();
>+
>+    // Bind current FBOs when exiting the function
>+    GCGLint boundFBO { 0 };
>+    GCGLint boundRenderbuffer { 0 };
>+    gl.getIntegerv(GL::FRAMEBUFFER_BINDING, makeGCGLSpan(&boundFBO, 1));
>+    gl.getIntegerv(GL::RENDERBUFFER_BINDING, makeGCGLSpan(&boundRenderbuffer, 1));
>+    auto scopedFBO = makeScopeExit([&gl, boundFBO, boundRenderbuffer]() {
>+        gl.bindFramebuffer(GL::FRAMEBUFFER, boundFBO);
>+        gl.bindFramebuffer(GL::RENDERBUFFER, boundRenderbuffer);
>+    });
>+
>+    // Set up color, depth and stencil formats
>+    bool useDepthStencil = m_attributes.stencil || m_attributes.depth;
>+    auto colorFormat = m_attributes.alpha ? GraphicsContextGL::RGBA8 : GraphicsContextGL::RGB8;
>+#if USE(OPENGL_ES)
>+    auto& extensions = reinterpret_cast<ExtensionsGLOpenGLES&>(gl.getExtensions());
>+    bool supportsPackedDepthStencil = useDepthStencil && extensions.supports("GL_OES_packed_depth_stencil");
>+    auto depthFormat = supportsPackedDepthStencil ? GL::DEPTH24_STENCIL8 : GL::DEPTH_COMPONENT16;
>+    auto stencilFormat = GL::STENCIL_INDEX8;
>+#else
>+    auto& extensions = reinterpret_cast<ExtensionsGLOpenGLCommon&>(gl.getExtensions());
>+    bool supportsPackedDepthStencil = useDepthStencil && extensions.supports("GL_EXT_packed_depth_stencil");
>+    auto depthFormat = supportsPackedDepthStencil ? GL::DEPTH24_STENCIL8 : GL::DEPTH_COMPONENT;
>+    auto stencilFormat = GL::STENCIL_COMPONENT;
>+#endif
>+
>+    // Set up recommended samples for WebXR.
>+    // FIXME: check if we can get recommended values from each device platform.
>+    if (m_attributes.antialias) {
>+        GCGLint maxSampleCount;
>+        gl.getIntegerv(ExtensionsGL::MAX_SAMPLES, makeGCGLSpan(&maxSampleCount, 1));
>+        // Using more than 4 samples might be overhead.
>+        m_sampleCount = std::min(4, maxSampleCount);
>+    }
>+
>+#if USE(OPENGL_ES)
>+    // Use multisampled_render_to_texture extension if available.
>+    if (m_attributes.antialias && extensions.isImagination()) {
>+        // framebufferTexture2DMultisampleIMG is set up in startFrame call.
>+        if (!useDepthStencil)
>+            return true;
>+        
>+        gl.bindFramebuffer(GL::FRAMEBUFFER, m_framebuffer->object());
>+        m_depthStencilBuffer = gl.createRenderbuffer();
>+        if (supportsPackedDepthStencil) {
>+            gl.bindRenderbuffer(GL::RENDERBUFFER, m_depthStencilBuffer);
>+            extensions.renderbufferStorageMultisampleANGLE(GL::RENDERBUFFER, m_sampleCount, depthFormat, m_width, m_height);
>+            if (m_attributes.stencil)
>+                gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::STENCIL_ATTACHMENT, GL::RENDERBUFFER, m_depthStencilBuffer);
>+            if (m_attributes.depth)
>+                gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::DEPTH_ATTACHMENT, GL::RENDERBUFFER, m_depthStencilBuffer);
>+        } else {
>+            if (m_attributes.stencil) {
>+                m_stencilBuffer = gl.createRenderbuffer();
>+                gl.bindRenderbuffer(GL::RENDERBUFFER, m_stencilBuffer);
>+                extensions.renderbufferStorageMultisampleANGLE(GL::RENDERBUFFER, m_sampleCount, stencilFormat, m_width, m_height);
>+                gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::STENCIL_ATTACHMENT, GL::RENDERBUFFER, m_stencilBuffer);
>+            }
>+            if (m_attributes.depth) {
>+                gl.bindRenderbuffer(GL::RENDERBUFFER, m_depthStencilBuffer);
>+                extensions.renderbufferStorageMultisampleANGLE(GL::RENDERBUFFER, m_sampleCount, depthFormat, m_width, m_height);
>+                gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::DEPTH_ATTACHMENT, GL::RENDERBUFFER, m_depthStencilBuffer);
>+            }
>+        }
>+        return true;
>+    }
>+#endif // USE(OPENGL_ES)
>+
>+    if (m_attributes.antialias && m_context.isWebGL2()) {
>+        // Use an extra FBO for multisample if multisampled_render_to_texture is not supported.
>+        m_resolvedFBO = gl.createFramebuffer();
>+        m_multisampleColorBuffer = gl.createRenderbuffer();
>+        gl.bindFramebuffer(GL::FRAMEBUFFER, m_framebuffer->object());
>+        gl.bindRenderbuffer(GL::RENDERBUFFER, m_multisampleColorBuffer);
>+        gl.renderbufferStorageMultisample(GL::RENDERBUFFER, m_sampleCount, colorFormat, m_width, m_height);
>+        gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::COLOR_ATTACHMENT0, GL::RENDERBUFFER, m_multisampleColorBuffer);
>+        if (useDepthStencil) {
>+            m_depthStencilBuffer = gl.createRenderbuffer();
>+            if (supportsPackedDepthStencil) {
>+                gl.bindRenderbuffer(GL::RENDERBUFFER, m_depthStencilBuffer);
>+                gl.renderbufferStorageMultisample(GL::RENDERBUFFER, m_sampleCount, depthFormat, m_width, m_height);
>+                if (m_attributes.stencil)
>+                    gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::STENCIL_ATTACHMENT, GL::RENDERBUFFER, m_depthStencilBuffer);
>+                if (m_attributes.depth)
>+                    gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::DEPTH_ATTACHMENT, GL::RENDERBUFFER, m_depthStencilBuffer);
>+            } else {
>+                if (m_attributes.stencil) {
>+                    m_stencilBuffer = gl.createRenderbuffer();
>+                    gl.bindRenderbuffer(GL::RENDERBUFFER, m_stencilBuffer);
>+                    gl.renderbufferStorageMultisample(GL::RENDERBUFFER, m_sampleCount, stencilFormat, m_width, m_height);
>+                    gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::STENCIL_ATTACHMENT, GL::RENDERBUFFER, m_stencilBuffer);
>+                }
>+                if (m_attributes.depth) {
>+                    gl.bindRenderbuffer(GL::RENDERBUFFER, m_depthStencilBuffer);
>+                    gl.renderbufferStorageMultisample(GL::RENDERBUFFER, m_sampleCount, depthFormat, m_width, m_height);
>+                    gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::DEPTH_ATTACHMENT, GL::RENDERBUFFER, m_depthStencilBuffer);
>+                }
>+            }
>+        }
>+        return gl.checkFramebufferStatus(GL::FRAMEBUFFER) == GL::FRAMEBUFFER_COMPLETE;
>+    }
>+    if (useDepthStencil) {
>+        gl.bindFramebuffer(GL::FRAMEBUFFER, m_framebuffer->object());
>+        m_depthStencilBuffer = gl.createRenderbuffer();
>+        if (supportsPackedDepthStencil) {
>+            gl.bindRenderbuffer(GL::RENDERBUFFER, m_depthStencilBuffer);
>+            gl.renderbufferStorage(GL::RENDERBUFFER, depthFormat, m_width, m_height);
>+            if (m_attributes.stencil)
>+                gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::STENCIL_ATTACHMENT, GL::RENDERBUFFER, m_depthStencilBuffer);
>+            if (m_attributes.depth)
>+                gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::DEPTH_ATTACHMENT, GL::RENDERBUFFER, m_depthStencilBuffer);
>+        } else {
>+            if (m_attributes.stencil) {
>+                m_stencilBuffer = gl.createRenderbuffer();
>+                gl.bindRenderbuffer(GL::RENDERBUFFER, m_stencilBuffer);
>+                gl.renderbufferStorage(GL::RENDERBUFFER, stencilFormat, m_width, m_height);
>+                gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::STENCIL_ATTACHMENT, GL::RENDERBUFFER, m_stencilBuffer);
>+            }
>+            if (m_attributes.depth) {
>+                gl.bindRenderbuffer(GL::RENDERBUFFER, m_depthStencilBuffer);
>+                gl.renderbufferStorage(GL::RENDERBUFFER, depthFormat, m_width, m_height);
>+                gl.framebufferRenderbuffer(GL::FRAMEBUFFER, GL::DEPTH_ATTACHMENT, GL::RENDERBUFFER, m_depthStencilBuffer);
>+            }
>+        }
>+    }
>+
>+    return true;
> }
> 
> } // namespace WebCore
>diff --git a/Source/WebCore/Modules/webxr/WebXRWebGLLayer.h b/Source/WebCore/Modules/webxr/WebXRWebGLLayer.h
>index 2eef21e7b021ca71c57a18929faa26f3325c6ba3..e7b4d5914a43ae4c340f84a2087d122850878d26 100644
>--- a/Source/WebCore/Modules/webxr/WebXRWebGLLayer.h
>+++ b/Source/WebCore/Modules/webxr/WebXRWebGLLayer.h
>@@ -29,6 +29,8 @@
> 
> #include "CanvasBase.h"
> #include "ExceptionOr.h"
>+#include "GraphicsTypesGL.h"
>+#include "PlatformXR.h"
> #include "WebXRLayer.h"
> #include <wtf/IsoMalloc.h>
> #include <wtf/Ref.h>
>@@ -41,9 +43,11 @@ class HTMLCanvasElement;
> class IntSize;
> class WebGLFramebuffer;
> class WebGLRenderingContext;
>+class WebGLRenderingContextBase;
> #if ENABLE(WEBGL2)
> class WebGL2RenderingContext;
> #endif
>+class WebXROpaqueFramebuffer;
> class WebXRSession;
> class WebXRView;
> class WebXRViewport;
>@@ -66,7 +70,7 @@ public:
>     bool antialias() const;
>     bool ignoreDepthValues() const;
> 
>-    WebGLFramebuffer* framebuffer() const;
>+    const WebGLFramebuffer* framebuffer() const;
>     unsigned framebufferWidth() const;
>     unsigned framebufferHeight() const;
> 
>@@ -80,17 +84,22 @@ public:
> 
>     HTMLCanvasElement* canvas() const;
> 
>+    // WebXRLayer
>+    void startFrame(const PlatformXR::Device::FrameData&) final;
>+    PlatformXR::Device::Layer endFrame() final;
>+
> private:
>-    WebXRWebGLLayer(Ref<WebXRSession>&&, WebXRRenderingContext&&, const XRWebGLLayerInit&);
>+    WebXRWebGLLayer(Ref<WebXRSession>&&, WebXRRenderingContext&&, std::unique_ptr<WebXROpaqueFramebuffer>&&, bool antialias, bool ignoreDepthValues, bool isCompositionEnabled);
>+
>+    // CanvasObserver
>+    void canvasChanged(CanvasBase&, const FloatRect&) final { };
>+    void canvasResized(CanvasBase&) final;
>+    void canvasDestroyed(CanvasBase&) final { }
> 
>     void computeViewports();
>     static IntSize computeNativeWebGLFramebufferResolution();
>     static IntSize computeRecommendedWebGLFramebufferResolution();
> 
>-    void canvasChanged(CanvasBase&, const FloatRect&) final { };
>-    void canvasResized(CanvasBase&) final;
>-    void canvasDestroyed(CanvasBase&) final { };
>-
>     Ref<WebXRSession> m_session;
>     WebXRRenderingContext m_context;
> 
>@@ -101,16 +110,51 @@ private:
> 
>     ViewportData m_leftViewportData;
>     ViewportData m_rightViewportData;
>+    std::unique_ptr<WebXROpaqueFramebuffer> m_framebuffer;
>     bool m_antialias { false };
>     bool m_ignoreDepthValues { false };
>     bool m_isCompositionEnabled { true };
>     bool m_viewportsDirty { true };
>+};
> 
>-    struct {
>-        RefPtr<WebGLFramebuffer> object;
>-        unsigned width { 0 };
>-        unsigned height { 0 };
>-    } m_framebuffer;
>+class WebXROpaqueFramebuffer {
>+public:
>+    struct Attributes {
>+        bool alpha { true };
>+        bool antialias { true };
>+        bool depth { true };
>+        bool stencil { false };
>+    };
>+
>+
>+    static std::unique_ptr<WebXROpaqueFramebuffer> create(PlatformXR::LayerHandle, WebGLRenderingContextBase&, Attributes&&, uint32_t width, uint32_t height);
>+    ~WebXROpaqueFramebuffer();
>+
>+    PlatformXR::LayerHandle handle() const { return m_handle; }
>+    const WebGLFramebuffer& framebuffer() const { return m_framebuffer.get(); }
>+    uint32_t width() const { return m_width; }
>+    uint32_t height() const { return m_height; }
>+
>+    void startFrame(const PlatformXR::Device::FrameData::LayerData&);
>+    void endFrame();
>+
>+private:
>+    WebXROpaqueFramebuffer(PlatformXR::LayerHandle, Ref<WebGLFramebuffer>&&, WebGLRenderingContextBase&, Attributes&&, uint32_t width, uint32_t height);
>+
>+    bool setupFramebuffer();
>+
>+    PlatformXR::LayerHandle m_handle;
>+    Ref<WebGLFramebuffer> m_framebuffer;
>+    WebGLRenderingContextBase& m_context;
>+    Attributes m_attributes;
>+    uint32_t m_width { 0 };
>+    uint32_t m_height { 0 };
>+    PlatformGLObject m_depthStencilBuffer { 0 };
>+    PlatformGLObject m_stencilBuffer { 0 };
>+    PlatformGLObject m_multisampleColorBuffer { 0 };
>+    PlatformGLObject m_resolvedFBO { 0 };
>+    GCGLint m_sampleCount { 0 };
>+    PlatformGLObject m_opaqueTexture { 0 };
> };
> 
> } // namespace WebCore
>diff --git a/Source/WebCore/Sources.txt b/Source/WebCore/Sources.txt
>index 9b77bf7f05b83932a7fcca44178b0a002061ccd7..0964001d9bfd07152672e7bff7aa3c83280afe31 100644
>--- a/Source/WebCore/Sources.txt
>+++ b/Source/WebCore/Sources.txt
>@@ -2178,6 +2178,8 @@ platform/text/TextEncodingDetectorICU.cpp
> platform/text/TextEncodingRegistry.cpp
> platform/xr/openxr/OpenXRInstance.cpp @no-unify
> platform/xr/openxr/OpenXRExtensions.cpp @no-unify
>+platform/xr/openxr/OpenXRLayer.cpp @no-unify
>+platform/xr/openxr/OpenXRSwapchain.cpp @no-unify
> platform/xr/openxr/PlatformXROpenXR.cpp @no-unify
> plugins/DOMMimeType.cpp
> plugins/DOMMimeTypeArray.cpp
>diff --git a/Source/WebCore/html/canvas/WebGL2RenderingContext.cpp b/Source/WebCore/html/canvas/WebGL2RenderingContext.cpp
>index 9df3895a295ce0d92ef9baa65f58ab038c893644..21dea1f095e4fc031e628dcafd199b2928814eab 100644
>--- a/Source/WebCore/html/canvas/WebGL2RenderingContext.cpp
>+++ b/Source/WebCore/html/canvas/WebGL2RenderingContext.cpp
>@@ -2815,6 +2815,14 @@ WebGLAny WebGL2RenderingContext::getFramebufferAttachmentParameter(GCGLenum targ
>             return m_context->getFramebufferAttachmentParameteri(target, attachment, pname);
>         }
>     }
>+
>+#if ENABLE(WEBXR)
>+    if (targetFramebuffer->isOpaque()) {
>+        synthesizeGLError(GraphicsContextGL::INVALID_OPERATION, "getFramebufferAttachmentParameter", "An opaque framebuffer's attachments cannot be inspected or changed");
>+        return nullptr;
>+    }
>+#endif
>+
>     if (!validateNonDefaultFramebufferAttachment(functionName, attachment))
>         return nullptr;
> 
>diff --git a/Source/WebCore/html/canvas/WebGLFramebuffer.cpp b/Source/WebCore/html/canvas/WebGLFramebuffer.cpp
>index fd69fadf60eb605b1b8d42fd557624ff001fe63a..95abc033e2c6ed4fea25949433cd130d7f35fb57 100644
>--- a/Source/WebCore/html/canvas/WebGLFramebuffer.cpp
>+++ b/Source/WebCore/html/canvas/WebGLFramebuffer.cpp
>@@ -309,6 +309,17 @@ Ref<WebGLFramebuffer> WebGLFramebuffer::create(WebGLRenderingContextBase& ctx)
>     return adoptRef(*new WebGLFramebuffer(ctx));
> }
> 
>+#if ENABLE(WEBXR)
>+
>+Ref<WebGLFramebuffer> WebGLFramebuffer::createOpaque(WebGLRenderingContextBase& ctx)
>+{
>+    auto framebuffer = adoptRef(*new WebGLFramebuffer(ctx));
>+    framebuffer->m_opaque = true;
>+    return framebuffer;
>+}
>+
>+#endif
>+
> WebGLFramebuffer::WebGLFramebuffer(WebGLRenderingContextBase& ctx)
>     : WebGLContextObject(ctx)
>     , m_hasEverBeenBound(false)
>@@ -489,6 +500,16 @@ GCGLenum WebGLFramebuffer::getColorBufferFormat() const
> 
> GCGLenum WebGLFramebuffer::checkStatus(const char** reason) const
> {
>+#if ENABLE(WEBXR)
>+    // https://immersive-web.github.io/webxr/#opaque-framebuffer
>+    if (m_opaque) {
>+        if (m_opaqueActive)
>+            return GL_FRAMEBUFFER_COMPLETE;
>+        *reason = "An opaque framebuffer is considered incomplete outside of a requestAnimationFrame";
>+        return GL_FRAMEBUFFER_UNSUPPORTED;
>+    }
>+#endif
>+
>     unsigned int count = 0;
>     GCGLsizei width = 0, height = 0;
>     bool haveDepth = false;
>diff --git a/Source/WebCore/html/canvas/WebGLFramebuffer.h b/Source/WebCore/html/canvas/WebGLFramebuffer.h
>index 7b6df1f725748f89ccda46a84cd7c362498a2df2..314d51f699f4a70348aced53137ca1873379acf6 100644
>--- a/Source/WebCore/html/canvas/WebGLFramebuffer.h
>+++ b/Source/WebCore/html/canvas/WebGLFramebuffer.h
>@@ -74,6 +74,9 @@ public:
>     virtual ~WebGLFramebuffer();
> 
>     static Ref<WebGLFramebuffer> create(WebGLRenderingContextBase&);
>+#if ENABLE(WEBXR)
>+    static Ref<WebGLFramebuffer> createOpaque(WebGLRenderingContextBase&);
>+#endif
> 
>     void setAttachmentForBoundFramebuffer(GCGLenum target, GCGLenum attachment, GCGLenum texTarget, WebGLTexture*, GCGLint level, GCGLint layer);
>     void setAttachmentForBoundFramebuffer(GCGLenum target, GCGLenum attachment, WebGLRenderbuffer*);
>@@ -116,6 +119,11 @@ public:
> 
>     void addMembersToOpaqueRoots(const WTF::AbstractLocker&, JSC::AbstractSlotVisitor&);
> 
>+#if ENABLE(WEBXR)
>+    bool isOpaque() const { return m_opaque; }
>+    void setOpaqueActive(bool active) { m_opaqueActive = active; }
>+#endif
>+
> private:
>     WebGLFramebuffer(WebGLRenderingContextBase&);
> 
>@@ -151,6 +159,12 @@ private:
> 
>     Vector<GCGLenum> m_drawBuffers;
>     Vector<GCGLenum> m_filteredDrawBuffers;
>+
>+#if ENABLE(WEBXR)
>+    bool m_opaque { false };
>+    bool m_opaqueActive { false };
>+    bool m_opaqueHasStencil { false };
>+#endif
> };
> 
> } // namespace WebCore
>diff --git a/Source/WebCore/html/canvas/WebGLRenderingContext.cpp b/Source/WebCore/html/canvas/WebGLRenderingContext.cpp
>index a2960341b517830df66e567947a817e5bd73e26c..c9a944c6e1029f44d3d04f2733520a910ec48d24 100644
>--- a/Source/WebCore/html/canvas/WebGLRenderingContext.cpp
>+++ b/Source/WebCore/html/canvas/WebGLRenderingContext.cpp
>@@ -305,6 +305,13 @@ WebGLAny WebGLRenderingContext::getFramebufferAttachmentParameter(GCGLenum targe
>         return nullptr;
>     }
> 
>+#if ENABLE(WEBXR)
>+    if (m_framebufferBinding->isOpaque()) {
>+        synthesizeGLError(GraphicsContextGL::INVALID_OPERATION, "getFramebufferAttachmentParameter", "An opaque framebuffer's attachments cannot be inspected or changed");
>+        return nullptr;
>+    }
>+#endif
>+
>     auto object = makeRefPtr(m_framebufferBinding->getAttachmentObject(attachment));
>     if (!object) {
>         if (pname == GraphicsContextGL::FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE)
>diff --git a/Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp b/Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp
>index 9f37f9f3e4a5f77d42879d6ad9bc655168961194..761c1f5ca98539fb8064df2fa1586df03616a12b 100644
>--- a/Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp
>+++ b/Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp
>@@ -2054,6 +2054,13 @@ void WebGLRenderingContextBase::deleteFramebuffer(WebGLFramebuffer* framebuffer)
> {
>     auto locker = holdLock(objectGraphLock());
> 
>+#if ENABLE(WEBXR)
>+    if (framebuffer && framebuffer->isOpaque()) {
>+        synthesizeGLError(GraphicsContextGL::INVALID_OPERATION, "deleteFramebuffer", "An opaque framebuffer's attachments cannot be inspected or changed");
>+        return;
>+    }
>+#endif
>+
>     if (!deleteObject(locker, framebuffer))
>         return;
> 
>@@ -2734,6 +2741,14 @@ void WebGLRenderingContextBase::framebufferRenderbuffer(GCGLenum target, GCGLenu
>         synthesizeGLError(GraphicsContextGL::INVALID_OPERATION, "framebufferRenderbuffer", "no framebuffer bound");
>         return;
>     }
>+
>+#if ENABLE(WEBXR)
>+    if (framebufferBinding->isOpaque()) {
>+        synthesizeGLError(GraphicsContextGL::INVALID_OPERATION, "framebufferRenderbuffer", "An opaque framebuffer's attachments cannot be inspected or changed");
>+        return;
>+    }
>+#endif
>+
>     framebufferBinding->setAttachmentForBoundFramebuffer(target, attachment, buffer);
>     applyStencilTest();
> }
>@@ -2757,6 +2772,13 @@ void WebGLRenderingContextBase::framebufferTexture2D(GCGLenum target, GCGLenum a
>         synthesizeGLError(GraphicsContextGL::INVALID_OPERATION, "framebufferTexture2D", "no framebuffer bound");
>         return;
>     }
>+#if ENABLE(WEBXR)
>+    if (framebufferBinding->isOpaque()) {
>+        synthesizeGLError(GraphicsContextGL::INVALID_OPERATION, "framebufferTexture2D", "An opaque framebuffer's attachments cannot be inspected or changed");
>+        return;
>+    }
>+#endif
>+
>     framebufferBinding->setAttachmentForBoundFramebuffer(target, attachment, textarget, texture, level, 0);
>     applyStencilTest();
> }
>diff --git a/Source/WebCore/platform/xr/PlatformXR.h b/Source/WebCore/platform/xr/PlatformXR.h
>index d97d4f181b13d269892dbf5ebc33f55933e25676..574bf33b1fe00e185ec8b8b36ab8135709a8fab1 100644
>--- a/Source/WebCore/platform/xr/PlatformXR.h
>+++ b/Source/WebCore/platform/xr/PlatformXR.h
>@@ -19,6 +19,8 @@
> #pragma once
> 
> #include "FloatPoint3D.h"
>+#include "GraphicsTypesGL.h"
>+#include "IntRect.h"
> #include "IntSize.h"
> #include <memory>
> #include <wtf/CompletionHandler.h>
>@@ -50,6 +52,8 @@ enum class Eye {
>     Right,
> };
> 
>+using LayerHandle = int;
>+
> #if ENABLE(WEBXR)
> 
> class TrackingAndRenderingClient : public CanMakeWeakPtr<TrackingAndRenderingClient> {
>@@ -77,6 +81,15 @@ public:
>     bool supportsOrientationTracking() const { return m_supportsOrientationTracking; }
>     bool supportsViewportScaling() const { return m_supportsViewportScaling; }
> 
>+    // Returns the value that the device's recommended resolution must be multiplied by
>+    // to yield the device's native framebuffer resolution.
>+    virtual double nativeFramebufferScalingFactor() const { return 1.0; }
>+    // Returns the value that the device's recommended resolution must be multiplied by
>+    // to yield the device's max framebuffer resolution. This resolution can be larger than
>+    // the native resolution if the device supports supersampling.
>+    virtual double maxFramebufferScalingFactor() const { return nativeFramebufferScalingFactor(); }
>+
>+
>     virtual void initializeTrackingAndRendering(SessionMode) = 0;
>     virtual void shutDownTrackingAndRendering() = 0;
>     void setTrackingAndRenderingClient(WeakPtr<TrackingAndRenderingClient>&& client) { m_trackingAndRenderingClient = WTFMove(client); }
>@@ -85,6 +98,8 @@ public:
>     // when the platform has completed all steps to shut down the XR session.
>     virtual bool supportsSessionShutdownNotification() const { return false; }
>     virtual void initializeReferenceSpace(ReferenceSpaceType) = 0;
>+    virtual Optional<LayerHandle> createLayerProjection(uint32_t width, uint32_t height, bool alpha) = 0;
>+    virtual void deleteLayer(LayerHandle) = 0;
> 
>     struct FrameData {
>         struct FloatQuaternion {
>@@ -119,14 +134,31 @@ public:
>             Vector<WebCore::FloatPoint> bounds;
>         };
> 
>+        struct LayerData {
>+            PlatformGLObject opaqueTexture { 0 };
>+        };
>+
>         bool isTrackingValid { false };
>         bool isPositionValid { false };
>         bool isPositionEmulated { false };
>+        bool shouldRender { false };
>         long predictedDisplayTime { 0 };
>         Pose origin;
>         Optional<Pose> floorTransform;
>         StageParameters stageParameters;
>         Vector<View> views;
>+        HashMap<LayerHandle, LayerData> layers;
>+    };
>+
>+    struct LayerView {
>+        Eye eye { Eye::None };
>+        WebCore::IntRect viewport;
>+    };
>+
>+    struct Layer {
>+        LayerHandle handle { 0 };
>+        bool visible { true };
>+        Vector<LayerView> views;
>     };
> 
>     struct ViewData {
>@@ -138,6 +170,7 @@ public:
> 
>     using RequestFrameCallback = Function<void(FrameData&&)>;
>     virtual void requestFrame(RequestFrameCallback&&) = 0;
>+    virtual void submitFrame(Vector<Layer>&&) { };
> protected:
>     Device() = default;
> 
>diff --git a/Source/WebCore/platform/xr/openxr/OpenXRLayer.cpp b/Source/WebCore/platform/xr/openxr/OpenXRLayer.cpp
>new file mode 100644
>index 0000000000000000000000000000000000000000..6e43f1c8031606de6a50e846020ceee03154b663
>--- /dev/null
>+++ b/Source/WebCore/platform/xr/openxr/OpenXRLayer.cpp
>@@ -0,0 +1,106 @@
>+/*
>+ * Copyright (C) 2021 Igalia, S.L.
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Library General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Library General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Library General Public License
>+ * aint with this library; see the file COPYING.LIB.  If not, write to
>+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
>+ * Boston, MA 02110-1301, USA.
>+ */
>+
>+#include "config.h"
>+#include "OpenXRLayer.h"
>+
>+#if ENABLE(WEBXR) && USE(OPENXR)
>+
>+using namespace WebCore;
>+
>+namespace PlatformXR {
>+
>+static int sHandleIndex = 1;
>+
>+OpenXRLayer::OpenXRLayer()
>+    :  m_handle(sHandleIndex++)
>+{
>+}
>+
>+// OpenXRLayerProjection
>+
>+std::unique_ptr<OpenXRLayerProjection> OpenXRLayerProjection::create(XrInstance instance, XrSession session, uint32_t width, uint32_t height, int64_t format, uint32_t sampleCount)
>+{
>+    if (!width || !height || !sampleCount)
>+        return nullptr;
>+
>+    auto info = createStructure<XrSwapchainCreateInfo, XR_TYPE_SWAPCHAIN_CREATE_INFO>();
>+    info.arraySize = 1;
>+    info.format = format;
>+    info.width = width;
>+    info.height = height;
>+    info.mipCount = 1;
>+    info.faceCount = 1;
>+    info.arraySize = 1;
>+    info.sampleCount = sampleCount;
>+    info.usageFlags = XR_SWAPCHAIN_USAGE_SAMPLED_BIT | XR_SWAPCHAIN_USAGE_COLOR_ATTACHMENT_BIT;
>+
>+    auto swapchain = OpenXRSwapchain::create(instance, session, info);
>+    if (!swapchain)
>+        return nullptr;
>+
>+    return std::unique_ptr<OpenXRLayerProjection>(new OpenXRLayerProjection(makeUniqueRefFromNonNullUniquePtr(WTFMove(swapchain))));
>+}
>+
>+OpenXRLayerProjection::OpenXRLayerProjection(UniqueRef<OpenXRSwapchain>&& swapchain)
>+    : m_swapchain(WTFMove(swapchain))
>+    , m_layerProjection(createStructure<XrCompositionLayerProjection, XR_TYPE_COMPOSITION_LAYER_PROJECTION>())
>+{
>+}
>+
>+Optional<Device::FrameData::LayerData> OpenXRLayerProjection::startFrame()
>+{
>+    auto texture = m_swapchain->acquireImage();
>+    if (!texture)
>+        return WTF::nullopt;
>+
>+    return Device::FrameData::LayerData { *texture };
>+}
>+
>+Optional<XrCompositionLayerBaseHeader*> OpenXRLayerProjection::endFrame(const Device::Layer& layer, XrSpace space, const Vector<XrView>& frameViews)
>+{
>+    ASSERT(layer.views.size() == frameViews.size());
>+
>+    auto viewCount = frameViews.size();
>+    m_projectionViews.fill(createStructure<XrCompositionLayerProjectionView, XR_TYPE_COMPOSITION_LAYER_PROJECTION_VIEW>(), viewCount);
>+    m_layerProjection.layerFlags = XR_COMPOSITION_LAYER_BLEND_TEXTURE_SOURCE_ALPHA_BIT;
>+    for (uint32_t i = 0; i < viewCount; ++i) {
>+        m_projectionViews[i].pose = frameViews[i].pose;
>+        m_projectionViews[i].fov = frameViews[i].fov;
>+        m_projectionViews[i].subImage.swapchain = m_swapchain->swapchain();
>+
>+        auto& viewport = layer.views[i].viewport;
>+
>+        m_projectionViews[i].subImage.imageRect.offset = { viewport.x(), viewport.y() };
>+        m_projectionViews[i].subImage.imageRect.extent = { viewport.width(), viewport.height() };
>+    }
>+
>+    m_layerProjection.space = space;
>+    m_layerProjection.viewCount = m_projectionViews.size();
>+    m_layerProjection.views = m_projectionViews.data();
>+
>+    m_swapchain->releaseImage();
>+
>+    return reinterpret_cast<XrCompositionLayerBaseHeader*>(&m_layerProjection);
>+}
>+
>+
>+} // namespace PlatformXR
>+
>+#endif // ENABLE(WEBXR) && USE(OPENXR)
>diff --git a/Source/WebCore/platform/xr/openxr/OpenXRLayer.h b/Source/WebCore/platform/xr/openxr/OpenXRLayer.h
>new file mode 100644
>index 0000000000000000000000000000000000000000..fbe1239f2625fb54cc57061e414c81700b86c69f
>--- /dev/null
>+++ b/Source/WebCore/platform/xr/openxr/OpenXRLayer.h
>@@ -0,0 +1,67 @@
>+/*
>+ * Copyright (C) 2021 Igalia, S.L.
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Library General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Library General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Library General Public License
>+ * aint with this library; see the file COPYING.LIB.  If not, write to
>+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
>+ * Boston, MA 02110-1301, USA.
>+ */
>+
>+#pragma once
>+
>+#if ENABLE(WEBXR) && USE(OPENXR)
>+
>+#include "OpenXRSwapchain.h"
>+#include "OpenXRUtils.h"
>+#include "PlatformXR.h"
>+
>+#include <wtf/Noncopyable.h>
>+#include <wtf/UniqueRef.h>
>+#include <wtf/Vector.h>
>+
>+namespace PlatformXR {
>+
>+class OpenXRLayer {
>+    WTF_MAKE_FAST_ALLOCATED;
>+    WTF_MAKE_NONCOPYABLE(OpenXRLayer);
>+public:
>+    virtual ~OpenXRLayer() = default;
>+
>+    LayerHandle handle() { return m_handle; }
>+    virtual Optional<Device::FrameData::LayerData> startFrame() = 0;
>+    virtual Optional<XrCompositionLayerBaseHeader*> endFrame(const Device::Layer&, XrSpace, const Vector<XrView>&) = 0;
>+protected:
>+    OpenXRLayer();
>+
>+    const LayerHandle m_handle;
>+};
>+
>+class OpenXRLayerProjection final: public OpenXRLayer  {
>+    WTF_MAKE_FAST_ALLOCATED;
>+    WTF_MAKE_NONCOPYABLE(OpenXRLayerProjection);
>+public:
>+    static std::unique_ptr<OpenXRLayerProjection> create(XrInstance, XrSession, uint32_t width, uint32_t height, int64_t format, uint32_t sampleCount);
>+private:
>+    OpenXRLayerProjection(UniqueRef<OpenXRSwapchain>&&);
>+
>+    Optional<Device::FrameData::LayerData> startFrame() final;
>+    Optional<XrCompositionLayerBaseHeader*> endFrame(const Device::Layer&, XrSpace, const Vector<XrView>&) final;
>+
>+    UniqueRef<OpenXRSwapchain> m_swapchain;
>+    XrCompositionLayerProjection m_layerProjection;
>+    Vector<XrCompositionLayerProjectionView> m_projectionViews;
>+};
>+
>+} // namespace PlatformXR
>+
>+#endif // ENABLE(WEBXR) && USE(OPENXR)
>diff --git a/Source/WebCore/platform/xr/openxr/OpenXRSwapchain.cpp b/Source/WebCore/platform/xr/openxr/OpenXRSwapchain.cpp
>new file mode 100644
>index 0000000000000000000000000000000000000000..5d42246e0d9bdda6c3c4098321857ca6c04027b1
>--- /dev/null
>+++ b/Source/WebCore/platform/xr/openxr/OpenXRSwapchain.cpp
>@@ -0,0 +1,113 @@
>+/*
>+ * Copyright (C) 2020 Igalia, S.L.
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Library General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Library General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Library General Public License
>+ * aint with this library; see the file COPYING.LIB.  If not, write to
>+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
>+ * Boston, MA 02110-1301, USA.
>+ */
>+
>+#include "config.h"
>+
>+#if ENABLE(WEBXR) && USE(OPENXR)
>+#include "OpenXRSwapchain.h"
>+
>+using namespace WebCore;
>+
>+namespace PlatformXR {
>+
>+std::unique_ptr<OpenXRSwapchain> OpenXRSwapchain::create(XrInstance instance, XrSession session, const XrSwapchainCreateInfo& info)
>+{
>+    ASSERT(session != XR_NULL_HANDLE);
>+    ASSERT(info.faceCount == 1);
>+
>+    XrSwapchain swapchain { XR_NULL_HANDLE };
>+    auto result = xrCreateSwapchain(session, &info, &swapchain);
>+    RETURN_IF_FAILED(result, "xrEnumerateInstanceExtensionProperties", instance, nullptr);
>+    ASSERT(swapchain != XR_NULL_HANDLE);
>+
>+    uint32_t imageCount;
>+    result = xrEnumerateSwapchainImages(swapchain, 0, &imageCount, nullptr);
>+    RETURN_IF_FAILED(result, "xrEnumerateSwapchainImages", instance, nullptr);
>+    if (!imageCount) {
>+        LOG(XR, "xrEnumerateSwapchainImages(): no images\n");
>+        return nullptr;
>+    }
>+
>+    Vector<XrSwapchainImageOpenGLKHR> imageBuffers(imageCount, [] {
>+        return createStructure<XrSwapchainImageOpenGLKHR, XR_TYPE_SWAPCHAIN_IMAGE_OPENGL_KHR>();
>+    }());
>+
>+    Vector<XrSwapchainImageBaseHeader*> imageHeaders = imageBuffers.map([](auto& image) mutable {
>+        return (XrSwapchainImageBaseHeader*) &image;
>+    });
>+
>+    // Get images from an XrSwapchain
>+    result = xrEnumerateSwapchainImages(swapchain, imageCount, &imageCount, imageHeaders[0]);
>+    RETURN_IF_FAILED(result, "xrEnumerateSwapchainImages with imageCount", instance, nullptr);
>+
>+    return makeUnique<OpenXRSwapchain>(instance, session, swapchain, info, WTFMove(imageBuffers));
>+}
>+
>+OpenXRSwapchain::OpenXRSwapchain(XrInstance instance, XrSession session, XrSwapchain swapchain, const XrSwapchainCreateInfo& info, Vector<XrSwapchainImageOpenGLKHR>&& imageBuffers)
>+    : m_instance(instance)
>+    , m_session(session)
>+    , m_swapchain(swapchain)
>+    , m_createInfo(info)
>+    , m_imageBuffers(WTFMove(imageBuffers))
>+{
>+}
>+
>+OpenXRSwapchain::~OpenXRSwapchain()
>+{
>+    if (m_acquiredTexture)
>+        releaseImage();
>+    if (m_swapchain != XR_NULL_HANDLE)
>+        xrDestroySwapchain(m_swapchain);
>+}
>+
>+Optional<PlatformGLObject> OpenXRSwapchain::acquireImage()
>+{
>+    RELEASE_ASSERT_WITH_MESSAGE(!m_acquiredTexture , "Expected no acquired images. ReleaseImage not called?");
>+
>+    auto acquireInfo = createStructure<XrSwapchainImageAcquireInfo, XR_TYPE_SWAPCHAIN_IMAGE_ACQUIRE_INFO>();
>+    uint32_t swapchainImageIndex = 0;
>+    auto result = xrAcquireSwapchainImage(m_swapchain, &acquireInfo, &swapchainImageIndex);
>+    RETURN_IF_FAILED(result, "xrAcquireSwapchainImage", m_instance, WTF::nullopt);
>+
>+    RELEASE_ASSERT(swapchainImageIndex < m_imageBuffers.size());
>+
>+    auto waitInfo = createStructure<XrSwapchainImageWaitInfo, XR_TYPE_SWAPCHAIN_IMAGE_WAIT_INFO>();
>+    waitInfo.timeout = XR_INFINITE_DURATION;
>+    result = xrWaitSwapchainImage(m_swapchain, &waitInfo);
>+    RETURN_IF_FAILED(result, "xrWaitSwapchainImage", m_instance, WTF::nullopt);
>+
>+    m_acquiredTexture = m_imageBuffers[swapchainImageIndex].image;
>+
>+    return m_acquiredTexture;
>+}
>+
>+void OpenXRSwapchain::releaseImage()
>+{
>+    RELEASE_ASSERT_WITH_MESSAGE(m_acquiredTexture, "Expected a valid acquired image. AcquireImage not called?");
>+
>+    auto releaseInfo = createStructure<XrSwapchainImageReleaseInfo, XR_TYPE_SWAPCHAIN_IMAGE_RELEASE_INFO>();
>+    auto result = xrReleaseSwapchainImage(m_swapchain, &releaseInfo);
>+    LOG_IF_FAILED(result, "xrReleaseSwapchainImage", m_instance);
>+
>+    m_acquiredTexture = 0;
>+}
>+
>+} // namespace PlatformXR
>+
>+#endif // ENABLE(WEBXR) && USE(OPENXR)
>diff --git a/Source/WebCore/platform/xr/openxr/OpenXRSwapchain.h b/Source/WebCore/platform/xr/openxr/OpenXRSwapchain.h
>new file mode 100644
>index 0000000000000000000000000000000000000000..a76a6c6013cfe0152e3a25cb5bb5865bd7f8bf92
>--- /dev/null
>+++ b/Source/WebCore/platform/xr/openxr/OpenXRSwapchain.h
>@@ -0,0 +1,59 @@
>+/*
>+ * Copyright (C) 2021 Igalia, S.L.
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Library General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Library General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Library General Public License
>+ * aint with this library; see the file COPYING.LIB.  If not, write to
>+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
>+ * Boston, MA 02110-1301, USA.
>+ */
>+
>+#pragma once
>+
>+#if ENABLE(WEBXR) && USE(OPENXR)
>+
>+#include "GraphicsContextGL.h"
>+#include "OpenXRUtils.h"
>+
>+#include <wtf/Noncopyable.h>
>+#include <wtf/Vector.h>
>+
>+namespace PlatformXR {
>+
>+class OpenXRSwapchain final {
>+    WTF_MAKE_FAST_ALLOCATED;
>+    WTF_MAKE_NONCOPYABLE(OpenXRSwapchain);
>+public:
>+    static std::unique_ptr<OpenXRSwapchain> create(XrInstance, XrSession, const XrSwapchainCreateInfo&);
>+    ~OpenXRSwapchain();
>+
>+    Optional<PlatformGLObject> acquireImage();
>+    void releaseImage();
>+    XrSwapchain swapchain() const { return m_swapchain; }
>+    int32_t width() const { return m_createInfo.width; }
>+    int32_t height() const { return m_createInfo.height; }
>+
>+    OpenXRSwapchain(XrInstance, XrSession, XrSwapchain, const XrSwapchainCreateInfo&, Vector<XrSwapchainImageOpenGLKHR>&&);
>+
>+private:
>+    XrInstance m_instance;
>+    XrSession m_session;
>+    XrSwapchain m_swapchain;
>+    XrSwapchainCreateInfo m_createInfo;
>+    Vector<XrSwapchainImageOpenGLKHR> m_imageBuffers;
>+    PlatformGLObject m_acquiredTexture { 0 };
>+};
>+
>+
>+} // namespace PlatformXR
>+
>+#endif // ENABLE(WEBXR) && USE(OPENXR)
>diff --git a/Source/WebCore/platform/xr/openxr/OpenXRUtils.h b/Source/WebCore/platform/xr/openxr/OpenXRUtils.h
>index 085814fd00ba88ade24b58bf79288bff18568c42..62c5cb1a6bd7f8ca441a6460bf7e8b66c890e67a 100644
>--- a/Source/WebCore/platform/xr/openxr/OpenXRUtils.h
>+++ b/Source/WebCore/platform/xr/openxr/OpenXRUtils.h
>@@ -70,6 +70,11 @@ inline String resultToString(XrResult value, XrInstance instance)
>         return __VA_ARGS__;                                                                     \
>     }
> 
>+#define LOG_IF_FAILED(result, call, instance, ...)                                           \
>+    if (XR_FAILED(result))                                                                   \
>+        LOG(XR, "%s %s: %s\n", __func__, call, resultToString(result, instance).utf8().data());
>+
>+
> inline Device::FrameData::Pose XrPosefToPose(XrPosef pose)
> {
>     Device::FrameData::Pose result;
>@@ -81,7 +86,7 @@ inline Device::FrameData::Pose XrPosefToPose(XrPosef pose)
> inline Device::FrameData::View xrViewToPose(XrView view)
> {
>     Device::FrameData::View pose;
>-    pose.projection = Device::FrameData::Fov { view.fov.angleUp, -view.fov.angleDown, -view.fov.angleLeft, view.fov.angleRight };
>+    pose.projection = Device::FrameData::Fov { fabs(view.fov.angleUp), fabs(view.fov.angleDown), fabs(view.fov.angleLeft), fabs(view.fov.angleRight) };
>     pose.offset = XrPosefToPose(view.pose);
>     return pose;
> }
>diff --git a/Source/WebCore/platform/xr/openxr/PlatformXROpenXR.cpp b/Source/WebCore/platform/xr/openxr/PlatformXROpenXR.cpp
>index 205e783bfbd5d007633d6e56871e5869f7545e12..165182674eb5e08dda602fb0ef33b9041157b06f 100644
>--- a/Source/WebCore/platform/xr/openxr/PlatformXROpenXR.cpp
>+++ b/Source/WebCore/platform/xr/openxr/PlatformXROpenXR.cpp
>@@ -26,17 +26,12 @@
> 
> #include <wtf/NeverDestroyed.h>
> #include <wtf/Optional.h>
>+#include <wtf/threads/BinarySemaphore.h>
> 
> using namespace WebCore;
> 
> namespace PlatformXR {
> 
>-
>-static bool isSessionActive(XrSessionState state)
>-{
>-    return state == XR_SESSION_STATE_VISIBLE || state == XR_SESSION_STATE_FOCUSED;
>-}
>-
> static bool isSessionReady(XrSessionState state)
> {
>     return state >= XR_SESSION_STATE_READY  && state < XR_SESSION_STATE_STOPPING;
>@@ -102,6 +97,17 @@ void OpenXRDevice::initializeTrackingAndRendering(SessionMode mode)
>         auto& context = static_cast<GLContext&>(*m_egl);
>         context.makeContextCurrent();
> 
>+        GraphicsContextGLAttributes attributes;
>+        attributes.depth = false;
>+        attributes.stencil = false;
>+        attributes.antialias = false;
>+
>+        m_gl = GraphicsContextGL::create(attributes, nullptr);
>+        if (!m_gl) {
>+            LOG(XR, "Failed to create a valid GraphicsContextGL");
>+            return;
>+        }
>+
>         m_graphicsBinding.display = PlatformDisplay::sharedDisplay().eglDisplay();
>         m_graphicsBinding.context = context.platformContext();
>         m_graphicsBinding.config = m_egl->config();
>@@ -113,7 +119,7 @@ void OpenXRDevice::initializeTrackingAndRendering(SessionMode mode)
>         sessionCreateInfo.next = &m_graphicsBinding;
> 
>         result = xrCreateSession(m_instance, &sessionCreateInfo, &m_session);
>-        RETURN_IF_FAILED(result, "xrEnumerateInstanceExtensionProperties", m_instance);
>+        RETURN_IF_FAILED(result, "xrCreateSession", m_instance);
> 
>         // Create the default reference spaces
>         m_localSpace = createReferenceSpace(XR_REFERENCE_SPACE_TYPE_LOCAL);
>@@ -159,73 +165,109 @@ void OpenXRDevice::requestFrame(RequestFrameCallback&& callback)
>             return;
>         }
> 
>-        auto frameState = createStructure<XrFrameState, XR_TYPE_FRAME_STATE>();
>+        m_frameState = createStructure<XrFrameState, XR_TYPE_FRAME_STATE>();
>         auto frameWaitInfo = createStructure<XrFrameWaitInfo, XR_TYPE_FRAME_WAIT_INFO>();
>-        auto result = xrWaitFrame(m_session, &frameWaitInfo, &frameState);
>+        auto result = xrWaitFrame(m_session, &frameWaitInfo, &m_frameState);
>         RETURN_IF_FAILED(result, "xrWaitFrame", m_instance);
>-        XrTime predictedTime = frameState.predictedDisplayTime;
> 
>         auto frameBeginInfo = createStructure<XrFrameBeginInfo, XR_TYPE_FRAME_BEGIN_INFO>();
>         result = xrBeginFrame(m_session, &frameBeginInfo);
>         RETURN_IF_FAILED(result, "xrBeginFrame", m_instance);
> 
>         Device::FrameData frameData;
>-        frameData.predictedDisplayTime = frameState.predictedDisplayTime;
>+        frameData.predictedDisplayTime = m_frameState.predictedDisplayTime;
>+        frameData.shouldRender = m_frameState.shouldRender;
>         frameData.stageParameters = m_stageParameters;
> 
>         ASSERT(m_configurationViews.contains(m_currentViewConfigurationType));
>         const auto& configurationView = m_configurationViews.get(m_currentViewConfigurationType);
> 
>         uint32_t viewCount = configurationView.size();
>-        Vector<XrView> views(viewCount, [] {
>-            return createStructure<XrView, XR_TYPE_VIEW>();
>-        }());
>+        m_frameViews.fill(createStructure<XrView, XR_TYPE_VIEW>(), viewCount);
> 
>-
>-        if (isSessionActive(m_sessionState)) {
>+        if (m_frameState.shouldRender) {
>             // Query head location
>             auto location = createStructure<XrSpaceLocation, XR_TYPE_SPACE_LOCATION>();
>-            xrLocateSpace(m_viewSpace, m_localSpace, frameState.predictedDisplayTime, &location);
>+            xrLocateSpace(m_viewSpace, m_localSpace, m_frameState.predictedDisplayTime, &location);
>             frameData.isTrackingValid = location.locationFlags & XR_SPACE_LOCATION_ORIENTATION_VALID_BIT;
>             frameData.isPositionValid = location.locationFlags & XR_SPACE_LOCATION_POSITION_VALID_BIT;
>             frameData.isPositionEmulated = location.locationFlags & XR_SPACE_LOCATION_POSITION_TRACKED_BIT;
> 
>             if (frameData.isTrackingValid)
>                 frameData.origin = XrPosefToPose(location.pose);
>-            
> 
>             auto viewLocateInfo = createStructure<XrViewLocateInfo, XR_TYPE_VIEW_LOCATE_INFO>();
>-            viewLocateInfo.displayTime = predictedTime;
>-            viewLocateInfo.space = m_localSpace;
>+            viewLocateInfo.displayTime = m_frameState.predictedDisplayTime;
>+            viewLocateInfo.space = m_viewSpace;
> 
>             auto viewState = createStructure<XrViewState, XR_TYPE_VIEW_STATE>();
>             uint32_t viewCountOutput;
>-            result = xrLocateViews(m_session, &viewLocateInfo, &viewState, viewCount, &viewCountOutput, views.data());
>+            result = xrLocateViews(m_session, &viewLocateInfo, &viewState, viewCount, &viewCountOutput, m_frameViews.data());
>             if (!XR_FAILED(result)) {
>-                for (auto& view : views)
>+                for (auto& view : m_frameViews)
>                     frameData.views.append(xrViewToPose(view));
>             }
> 
>             // Query floor transform
>             if (m_stageSpace != XR_NULL_HANDLE) {
>                 auto floorLocation = createStructure<XrSpaceLocation, XR_TYPE_SPACE_LOCATION>();
>-                xrLocateSpace(m_stageSpace, m_localSpace, frameState.predictedDisplayTime, &floorLocation);
>+                xrLocateSpace(m_stageSpace, m_localSpace, m_frameState.predictedDisplayTime, &floorLocation);
>                 frameData.floorTransform = { XrPosefToPose(floorLocation.pose) };
>             }
>+
>+            for (auto& layer : m_layers) {
>+                auto layerData = layer.value->startFrame();
>+                if (layerData)
>+                    frameData.layers.add(layer.key, *layerData);
>+            }
>+        } else {
>+            // https://www.khronos.org/registry/OpenXR/specs/1.0/man/html/XrFrameState.html
>+            // When shouldRender is false the application should avoid heavy GPU work where possible,
>+            // for example by skipping layer rendering and then omitting those layers when calling xrEndFrame.
>+            // In this case we don't need to wait for OpenXRDevice::submitFrame to finish the frame.
>+            auto frameEndInfo = createStructure<XrFrameEndInfo, XR_TYPE_FRAME_END_INFO>();
>+            frameEndInfo.displayTime = m_frameState.predictedDisplayTime;
>+            frameEndInfo.environmentBlendMode = XR_ENVIRONMENT_BLEND_MODE_OPAQUE;
>+            frameEndInfo.layerCount = 0;
>+            frameEndInfo.layers = nullptr;
>+            LOG_IF_FAILED(xrEndFrame(m_session, &frameEndInfo), "xrEndFrame", m_instance);
>         }
> 
>         callOnMainThread([frameData = WTFMove(frameData), callback = WTFMove(callback)]() mutable {
>             callback(WTFMove(frameData));
>         });
>+    });
>+}
> 
>-
>-        Vector<const XrCompositionLayerBaseHeader*> layers;
>+void OpenXRDevice::submitFrame(Vector<Device::Layer>&& layers)
>+{
>+    ASSERT(m_frameState.shouldRender);
>+    
>+    m_queue.dispatch([this, layers = WTFMove(layers)]() mutable {
>+        Vector<const XrCompositionLayerBaseHeader*> frameEndLayers;
>+        if (m_frameState.shouldRender) {
>+            for (auto& layer : layers) {
>+                auto it = m_layers.find(layer.handle);
>+                if (it == m_layers.end()) {
>+                    LOG("Didn't find a OpenXRLayer with %d handle", layer.handle);
>+                    continue;
>+                }
>+                auto header = it->value->endFrame(layer, m_viewSpace, m_frameViews);
>+                if (!header) {
>+                    LOG("endFrame() call failed in OpenXRLayer with %d handle", layer.handle());
>+                    continue;
>+                }
>+
>+                frameEndLayers.append(*header);
>+            }
>+        }
> 
>         auto frameEndInfo = createStructure<XrFrameEndInfo, XR_TYPE_FRAME_END_INFO>();
>-        frameEndInfo.displayTime = predictedTime;
>+        frameEndInfo.displayTime = m_frameState.predictedDisplayTime;
>         frameEndInfo.environmentBlendMode = XR_ENVIRONMENT_BLEND_MODE_OPAQUE;
>-        frameEndInfo.layerCount = layers.size();
>-        result = xrEndFrame(m_session, &frameEndInfo);
>+        frameEndInfo.layerCount = frameEndLayers.size();
>+        frameEndInfo.layers = frameEndLayers.data();
>+        auto result = xrEndFrame(m_session, &frameEndInfo);
>         RETURN_IF_FAILED(result, "xrEndFrame", m_instance);
>     });
> }
>@@ -245,7 +287,39 @@ Vector<Device::ViewData> OpenXRDevice::views(SessionMode mode) const
>     return views;
> }
> 
>-Device::ListOfEnabledFeatures OpenXRDevice::collectEnabledFeatures()
>+Optional<LayerHandle> OpenXRDevice::createLayerProjection(uint32_t width, uint32_t height, bool alpha)
>+{
>+    Optional<LayerHandle> handle;
>+
>+    BinarySemaphore semaphore;
>+    m_queue.dispatch([this, width, height, alpha, &handle, &semaphore]() mutable {
>+        auto format = alpha ? GL_RGBA8 : GL_RGB8;
>+        int64_t sampleCount = 1;
>+
>+        auto it = m_configurationViews.find(m_currentViewConfigurationType);
>+        if (it != m_configurationViews.end())
>+            sampleCount = it->value[0].recommendedSwapchainSampleCount;
>+
>+        auto layer = OpenXRLayerProjection::create(m_instance, m_session, width, height, format, sampleCount);
>+        if (layer) {
>+            handle = layer->handle();
>+            m_layers.add(*handle, WTFMove(layer));
>+        }
>+
>+        semaphore.signal();
>+    });
>+    semaphore.wait();
>+
>+    return handle;
>+}
>+
>+void OpenXRDevice::deleteLayer(LayerHandle handle)
>+{
>+    m_layers.remove(handle);
>+}
>+
>+
>+Device::ListOfEnabledFeatures OpenXRDevice::collectEnabledFeatures() const
> {
>     Device::ListOfEnabledFeatures features;
> 
>@@ -416,6 +490,7 @@ void OpenXRDevice::endSession()
> void OpenXRDevice::resetSession()
> {
>     ASSERT(&RunLoop::current() == &m_queue.runLoop());
>+    m_layers.clear();
>     if (m_session != XR_NULL_HANDLE) {
>         xrDestroySession(m_session);
>         m_session = XR_NULL_HANDLE;
>@@ -427,6 +502,7 @@ void OpenXRDevice::resetSession()
>     m_stageParameters = { };
> 
>     // deallocate graphic resources
>+    m_gl = nullptr;
>     m_egl.reset();
> }
> 
>diff --git a/Source/WebCore/platform/xr/openxr/PlatformXROpenXR.h b/Source/WebCore/platform/xr/openxr/PlatformXROpenXR.h
>index e6ab184f12e4f57658bd8d66f9961b69afddd55b..0bbd90c3e29c67bad5c0dca2eea50482dc6203bc 100644
>--- a/Source/WebCore/platform/xr/openxr/PlatformXROpenXR.h
>+++ b/Source/WebCore/platform/xr/openxr/PlatformXROpenXR.h
>@@ -22,6 +22,8 @@
> #if ENABLE(WEBXR) && USE(OPENXR)
> 
> #include "GLContextEGL.h"
>+#include "GraphicsContextGL.h"
>+#include "OpenXRLayer.h"
> #include "OpenXRUtils.h"
> #include "PlatformXR.h"
> 
>@@ -56,10 +58,13 @@ private:
>     void initializeReferenceSpace(PlatformXR::ReferenceSpaceType) final;
>     bool supportsSessionShutdownNotification() const final { return true; }
>     void requestFrame(RequestFrameCallback&&) final;
>+    void submitFrame(Vector<Device::Layer>&&) final;
>     Vector<ViewData> views(SessionMode) const final;
>+    Optional<LayerHandle> createLayerProjection(uint32_t width, uint32_t height, bool alpha) final;
>+    void deleteLayer(LayerHandle) final;
> 
>     // Custom methods
>-    ListOfEnabledFeatures collectEnabledFeatures();
>+    ListOfEnabledFeatures collectEnabledFeatures() const;
>     void collectSupportedSessionModes();
>     void collectConfigurationViews();
>     XrSpace createReferenceSpace(XrReferenceSpaceType);
>@@ -79,6 +84,10 @@ private:
>     XrSessionState m_sessionState { XR_SESSION_STATE_UNKNOWN };
>     XrGraphicsBindingEGLMNDX m_graphicsBinding;
>     std::unique_ptr<WebCore::GLContextEGL> m_egl;
>+    RefPtr<WebCore::GraphicsContextGL> m_gl;
>+    XrFrameState m_frameState;
>+    Vector<XrView> m_frameViews;
>+    HashMap<LayerHandle, std::unique_ptr<OpenXRLayer>> m_layers;
> 
>     using ViewConfigurationPropertiesMap = HashMap<XrViewConfigurationType, XrViewConfigurationProperties, IntHash<XrViewConfigurationType>, WTF::StrongEnumHashTraits<XrViewConfigurationType>>;
>     ViewConfigurationPropertiesMap m_viewConfigurationProperties;
>diff --git a/Source/WebCore/testing/WebFakeXRDevice.cpp b/Source/WebCore/testing/WebFakeXRDevice.cpp
>index 33b5c2a305e7f213608e422eb6227c377071334a..1b77c95069c39dcc6050d78bd503c48a03189890 100644
>--- a/Source/WebCore/testing/WebFakeXRDevice.cpp
>+++ b/Source/WebCore/testing/WebFakeXRDevice.cpp
>@@ -29,6 +29,8 @@
> #if ENABLE(WEBXR)
> 
> #include "DOMPointReadOnly.h"
>+#include "GLContext.h"
>+#include "GraphicsContextGL.h"
> #include "JSDOMPromiseDeferred.h"
> #include "WebFakeXRInputController.h"
> #include <wtf/CompletionHandler.h>
>@@ -75,8 +77,17 @@ void SimulatedXRDevice::simulateShutdownCompleted()
> 
> WebCore::IntSize SimulatedXRDevice::recommendedResolution(PlatformXR::SessionMode)
> {
>-    // Return at least a 2 pixel size so we can have different viewports for left and right eyes
>-    return IntSize(2, 2);
>+    // Return at least a valid size for a framebuffer.
>+    return IntSize(32, 32);
>+}
>+
>+void SimulatedXRDevice::initializeTrackingAndRendering(PlatformXR::SessionMode)
>+{
>+    GraphicsContextGLAttributes attributes;
>+    attributes.depth = false;
>+    attributes.stencil = false;
>+    attributes.antialias = false;
>+    m_gl = GraphicsContextGL::create(attributes, nullptr);
> }
> 
> void SimulatedXRDevice::shutDownTrackingAndRendering()
>@@ -84,6 +95,11 @@ void SimulatedXRDevice::shutDownTrackingAndRendering()
>     if (m_supportsShutdownNotification)
>         simulateShutdownCompleted();
>     stopTimer();
>+    if (m_gl) {
>+        for (auto layer : m_layers)
>+            m_gl->deleteTexture(layer.value);
>+    }
>+    m_layers.clear();
> }
> 
> void SimulatedXRDevice::stopTimer()
>@@ -99,6 +115,7 @@ void SimulatedXRDevice::frameTimerFired()
>         update();
> 
>     FrameData data;
>+    data.shouldRender = true;
>     if (m_viewerOrigin) {
>         data.origin = *m_viewerOrigin;
>         data.isTrackingValid = true;
>@@ -122,6 +139,9 @@ void SimulatedXRDevice::frameTimerFired()
>         data.views.append(view);
>     }
> 
>+    for (auto& layer : m_layers)
>+        data.layers.add(layer.key, FrameData::LayerData { .opaqueTexture = layer.value });
>+
>     if (m_FrameCallback)
>         m_FrameCallback(WTFMove(data));
> }
>@@ -133,6 +153,36 @@ void SimulatedXRDevice::requestFrame(RequestFrameCallback&& callback)
>         m_frameTimer.startOneShot(FakeXRFrameTime);
> }
> 
>+Optional<PlatformXR::LayerHandle> SimulatedXRDevice::createLayerProjection(uint32_t width, uint32_t height, bool alpha)
>+{
>+    using GL = GraphicsContextGL;
>+    if (!m_gl)
>+        return WTF::nullopt;
>+    PlatformXR::LayerHandle handle = ++m_layerIndex;
>+    auto texture = m_gl->createTexture();
>+    auto colorFormat = alpha ? GL::RGBA8 : GL::RGB8;
>+
>+    m_gl->bindTexture(GL::TEXTURE_2D, texture);
>+    m_gl->texParameteri(GL::TEXTURE_2D, GL::TEXTURE_WRAP_S, GL::CLAMP_TO_EDGE);
>+    m_gl->texParameteri(GL::TEXTURE_2D, GL::TEXTURE_WRAP_T, GL::CLAMP_TO_EDGE);
>+    m_gl->texParameteri(GL::TEXTURE_2D, GL::TEXTURE_MIN_FILTER, GL::LINEAR);
>+    m_gl->texParameteri(GL::TEXTURE_2D, GL::TEXTURE_MAG_FILTER, GL::LINEAR);
>+    m_gl->texStorage2D(GL::TEXTURE_2D, 1, colorFormat, width, height);
>+
>+    m_layers.add(handle, texture);
>+    return handle;    
>+}
>+
>+void SimulatedXRDevice::deleteLayer(PlatformXR::LayerHandle handle)
>+{
>+    auto it = m_layers.find(handle);
>+    if (it != m_layers.end()) {
>+        if (m_gl)
>+            m_gl->deleteTexture(it->value);
>+        m_layers.remove(it);
>+    }
>+}
>+
> Vector<PlatformXR::Device::ViewData> SimulatedXRDevice::views(PlatformXR::SessionMode mode) const
> {
>     if (mode == PlatformXR::SessionMode::ImmersiveVr)
>diff --git a/Source/WebCore/testing/WebFakeXRDevice.h b/Source/WebCore/testing/WebFakeXRDevice.h
>index e127c059d31864b4c8d08263fd1d29fca4351c79..c73c0f39182295d82026a4d4ad449fbc69d532e3 100644
>--- a/Source/WebCore/testing/WebFakeXRDevice.h
>+++ b/Source/WebCore/testing/WebFakeXRDevice.h
>@@ -38,6 +38,9 @@
> #include <wtf/Vector.h>
> 
> namespace WebCore {
>+class GLContext;
>+class GraphicsContextGL;
>+
> class FakeXRView final : public RefCounted<FakeXRView> {
> public:
>     static Ref<FakeXRView> create(XREye eye) { return adoptRef(*new FakeXRView(eye)); }
>@@ -81,12 +84,14 @@ public:
>     void scheduleOnNextFrame(Function<void()>&&);
> private:
>     WebCore::IntSize recommendedResolution(PlatformXR::SessionMode) final;
>-    void initializeTrackingAndRendering(PlatformXR::SessionMode) final { }
>+    void initializeTrackingAndRendering(PlatformXR::SessionMode) final;
>     void shutDownTrackingAndRendering() final;
>     bool supportsSessionShutdownNotification() const final { return m_supportsShutdownNotification; }
>     void initializeReferenceSpace(PlatformXR::ReferenceSpaceType) final { }
>     Vector<PlatformXR::Device::ViewData> views(PlatformXR::SessionMode) const final;
>     void requestFrame(RequestFrameCallback&&) final;
>+    Optional<PlatformXR::LayerHandle> createLayerProjection(uint32_t width, uint32_t height, bool alpha) final;
>+    void deleteLayer(PlatformXR::LayerHandle) final;
> 
>     void stopTimer();
>     void frameTimerFired();
>@@ -101,6 +106,9 @@ private:
>     RequestFrameCallback m_FrameCallback;
>     Vector<Function<void()>> m_pendingUpdates;
>     FrameData::StageParameters m_stageParameters;
>+    RefPtr<WebCore::GraphicsContextGL> m_gl;
>+    HashMap<PlatformXR::LayerHandle, PlatformGLObject> m_layers;
>+    uint32_t m_layerIndex { 0 };
> };
> 
> class WebFakeXRDevice final : public RefCounted<WebFakeXRDevice> {
>diff --git a/LayoutTests/ChangeLog b/LayoutTests/ChangeLog
>index c0ece4190c2739b9d62db60b6ea6ea23f892c7b7..727b28ef87cb0a0d3bf827af4ddee7a31c54ddec 100644
>--- a/LayoutTests/ChangeLog
>+++ b/LayoutTests/ChangeLog
>@@ -1,3 +1,14 @@
>+2021-03-02  Imanol Fernandez  <ifernandez@igalia.com>
>+
>+        Implement WebXR Opaque Framebuffer
>+        https://bugs.webkit.org/show_bug.cgi?id=222607
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Update WebXR Opaque Framebuffer test expectations.
>+
>+        * platform/wpe/TestExpectations:
>+
> 2021-03-05  Imanol Fernandez  <ifernandez@igalia.com>
> 
>         XRFrame getViewerPose has emulatedPosition set properly
>diff --git a/LayoutTests/imported/w3c/ChangeLog b/LayoutTests/imported/w3c/ChangeLog
>index 60879ed4815e2706483f552ba96a09933cb5cfea..bc1584d7b8d23200b69dd4ea5f7e5ccee3c9a5d1 100644
>--- a/LayoutTests/imported/w3c/ChangeLog
>+++ b/LayoutTests/imported/w3c/ChangeLog
>@@ -1,3 +1,15 @@
>+2021-03-02  Imanol Fernandez  <ifernandez@igalia.com>
>+
>+        Implement WebXR Opaque Framebuffer
>+        https://bugs.webkit.org/show_bug.cgi?id=222607
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Update WebXR Opaque Framebuffer test expectations.
>+
>+        * web-platform-tests/webxr/xrWebGLLayer_framebuffer_draw.https-expected.txt: Added.
>+        * web-platform-tests/webxr/xrWebGLLayer_opaque_framebuffer.https-expected.txt: Added.
>+
> 2021-03-05  Chris Lord  <clord@igalia.com>
> 
>         Allow CSS font-styling for canvas without RenderStyle
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/webxr/xrWebGLLayer_framebuffer_draw.https-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/webxr/xrWebGLLayer_framebuffer_draw.https-expected.txt
>new file mode 100644
>index 0000000000000000000000000000000000000000..0f09dc9fdc2233ad4357bbb399a63a1aad003945
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/webxr/xrWebGLLayer_framebuffer_draw.https-expected.txt
>@@ -0,0 +1,7 @@
>+CONSOLE MESSAGE: WebGL: INVALID_FRAMEBUFFER_OPERATION: clear: An opaque framebuffer is considered incomplete outside of a requestAnimationFrame
>+CONSOLE MESSAGE: WebGL: INVALID_FRAMEBUFFER_OPERATION: clear: An opaque framebuffer is considered incomplete outside of a requestAnimationFrame
>+CONSOLE MESSAGE: WebGL: INVALID_FRAMEBUFFER_OPERATION: drawArrays: An opaque framebuffer is considered incomplete outside of a requestAnimationFrame
>+CONSOLE MESSAGE: WebGL: INVALID_FRAMEBUFFER_OPERATION: drawElements: An opaque framebuffer is considered incomplete outside of a requestAnimationFrame
>+
>+PASS Ensure a WebGL layer's framebuffer can only be drawn to inside a XR frame
>+
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/webxr/xrWebGLLayer_opaque_framebuffer.https-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/webxr/xrWebGLLayer_opaque_framebuffer.https-expected.txt
>new file mode 100644
>index 0000000000000000000000000000000000000000..c5cc76f5d96c7e90725f567e2c347e9fd0adcf10
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/webxr/xrWebGLLayer_opaque_framebuffer.https-expected.txt
>@@ -0,0 +1,21 @@
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: deleteFramebuffer: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: getFramebufferAttachmentParameter: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: framebufferTexture2D: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: framebufferRenderbuffer: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: INVALID_OPERATION: framebufferRenderbuffer: An opaque framebuffer's attachments cannot be inspected or changed
>+CONSOLE MESSAGE: WebGL: checkFramebufferStatus:An opaque framebuffer is considered incomplete outside of a requestAnimationFrame
>+
>+PASS Ensure that the framebuffer given by the WebGL layer is opaque for immersive
>+PASS Ensure that the framebuffer given by the WebGL layer is opaque for non-immersive
>+
>diff --git a/LayoutTests/platform/wpe/TestExpectations b/LayoutTests/platform/wpe/TestExpectations
>index 016b4479489ffa2fabab523121cb4a8c0c44c573..09d253b552418d93228bf184fa9edee114964d89 100644
>--- a/LayoutTests/platform/wpe/TestExpectations
>+++ b/LayoutTests/platform/wpe/TestExpectations
>@@ -648,7 +648,9 @@ imported/w3c/web-platform-tests/webxr/xrSession_requestReferenceSpace.https.html
> imported/w3c/web-platform-tests/webxr/xrSession_viewer_referenceSpace.https.html [ Pass ]
> imported/w3c/web-platform-tests/webxr/xrViewport_valid.https.html [ Pass ]
> imported/w3c/web-platform-tests/webxr/xrWebGLLayer_constructor.https.html [ Pass ]
>+imported/w3c/web-platform-tests/webxr/xrWebGLLayer_framebuffer_draw.https.html [ Pass ]
> imported/w3c/web-platform-tests/webxr/xrWebGLLayer_framebuffer_sameObject.https.html [ Pass ]
>+imported/w3c/web-platform-tests/webxr/xrWebGLLayer_opaque_framebuffer.https.html [ Pass ]
> imported/w3c/web-platform-tests/webxr/xrWebGLLayer_viewports.https.html [ Pass ]
> imported/w3c/web-platform-tests/webxr/render_state_vertical_fov_immersive.https.html [ Pass ]
> imported/w3c/web-platform-tests/webxr/render_state_update.https.html [ Pass ]

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Attachments on bug 222607: 421979 | 421982 | 422371 | 422562 | 422564 | 423181 | 423319 | 423590 | 423673