Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2383 insertions, 0 deletions

diff --git a/gfx/angle/checkout/src/libANGLE/Framebuffer.cpp b/gfx/angle/checkout/src/libANGLE/Framebuffer.cpp
new file mode 100644
index 0000000000..64acc8a4cd
--- /dev/null
+++ b/gfx/angle/checkout/src/libANGLE/Framebuffer.cpp
@@ -0,0 +1,2383 @@
+//
+// Copyright (c) 2002-2014 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+// Framebuffer.cpp: Implements the gl::Framebuffer class. Implements GL framebuffer
+// objects and related functionality. [OpenGL ES 2.0.24] section 4.4 page 105.
+
+#include "libANGLE/Framebuffer.h"
+
+#include "common/Optional.h"
+#include "common/bitset_utils.h"
+#include "common/utilities.h"
+#include "libANGLE/Config.h"
+#include "libANGLE/Context.h"
+#include "libANGLE/Display.h"
+#include "libANGLE/FramebufferAttachment.h"
+#include "libANGLE/Renderbuffer.h"
+#include "libANGLE/Surface.h"
+#include "libANGLE/Texture.h"
+#include "libANGLE/angletypes.h"
+#include "libANGLE/formatutils.h"
+#include "libANGLE/renderer/ContextImpl.h"
+#include "libANGLE/renderer/FramebufferImpl.h"
+#include "libANGLE/renderer/GLImplFactory.h"
+#include "libANGLE/renderer/RenderbufferImpl.h"
+#include "libANGLE/renderer/SurfaceImpl.h"
+
+using namespace angle;
+
+namespace gl
+{
+
+namespace
+{
+
+bool CheckMultiviewStateMatchesForCompleteness(const FramebufferAttachment *firstAttachment,
+                                               const FramebufferAttachment *secondAttachment)
+{
+    ASSERT(firstAttachment && secondAttachment);
+    ASSERT(firstAttachment->isAttached() && secondAttachment->isAttached());
+
+    if (firstAttachment->getNumViews() != secondAttachment->getNumViews())
+    {
+        return false;
+    }
+    if (firstAttachment->getBaseViewIndex() != secondAttachment->getBaseViewIndex())
+    {
+        return false;
+    }
+    if (firstAttachment->isMultiview() != secondAttachment->isMultiview())
+    {
+        return false;
+    }
+    return true;
+}
+
+bool CheckAttachmentCompleteness(const Context *context, const FramebufferAttachment &attachment)
+{
+    ASSERT(attachment.isAttached());
+
+    const Extents &size = attachment.getSize();
+    if (size.width == 0 || size.height == 0)
+    {
+        return false;
+    }
+
+    if (!attachment.isRenderable(context))
+    {
+        return false;
+    }
+
+    if (attachment.type() == GL_TEXTURE)
+    {
+        // [EXT_geometry_shader] Section 9.4.1, "Framebuffer Completeness"
+        // If <image> is a three-dimensional texture or a two-dimensional array texture and the
+        // attachment is not layered, the selected layer is less than the depth or layer count,
+        // respectively, of the texture.
+        if (!attachment.isLayered())
+        {
+            if (attachment.layer() >= size.depth)
+            {
+                return false;
+            }
+        }
+        // If <image> is a three-dimensional texture or a two-dimensional array texture and the
+        // attachment is layered, the depth or layer count, respectively, of the texture is less
+        // than or equal to the value of MAX_FRAMEBUFFER_LAYERS_EXT.
+        else
+        {
+            if (static_cast<GLuint>(size.depth) >= context->getCaps().maxFramebufferLayers)
+            {
+                return false;
+            }
+        }
+
+        // ES3 specifies that cube map texture attachments must be cube complete.
+        // This language is missing from the ES2 spec, but we enforce it here because some
+        // desktop OpenGL drivers also enforce this validation.
+        // TODO(jmadill): Check if OpenGL ES2 drivers enforce cube completeness.
+        const Texture *texture = attachment.getTexture();
+        ASSERT(texture);
+        if (texture->getType() == TextureType::CubeMap &&
+            !texture->getTextureState().isCubeComplete())
+        {
+            return false;
+        }
+
+        if (!texture->getImmutableFormat())
+        {
+            GLuint attachmentMipLevel = static_cast<GLuint>(attachment.mipLevel());
+
+            // From the ES 3.0 spec, pg 213:
+            // If the value of FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is TEXTURE and the value of
+            // FRAMEBUFFER_ATTACHMENT_OBJECT_NAME does not name an immutable-format texture,
+            // then the value of FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL must be in the
+            // range[levelbase, q], where levelbase is the value of TEXTURE_BASE_LEVEL and q is
+            // the effective maximum texture level defined in the Mipmapping discussion of
+            // section 3.8.10.4.
+            if (attachmentMipLevel < texture->getBaseLevel() ||
+                attachmentMipLevel > texture->getMipmapMaxLevel())
+            {
+                return false;
+            }
+
+            // Form the ES 3.0 spec, pg 213/214:
+            // If the value of FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is TEXTURE and the value of
+            // FRAMEBUFFER_ATTACHMENT_OBJECT_NAME does not name an immutable-format texture and
+            // the value of FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL is not levelbase, then the
+            // texture must be mipmap complete, and if FRAMEBUFFER_ATTACHMENT_OBJECT_NAME names
+            // a cubemap texture, the texture must also be cube complete.
+            if (attachmentMipLevel != texture->getBaseLevel() && !texture->isMipmapComplete())
+            {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+bool CheckAttachmentSampleCompleteness(const Context *context,
+                                       const FramebufferAttachment &attachment,
+                                       bool colorAttachment,
+                                       Optional<int> *samples,
+                                       Optional<bool> *fixedSampleLocations)
+{
+    ASSERT(attachment.isAttached());
+
+    if (attachment.type() == GL_TEXTURE)
+    {
+        const Texture *texture = attachment.getTexture();
+        ASSERT(texture);
+
+        const ImageIndex &attachmentImageIndex = attachment.getTextureImageIndex();
+        bool fixedSampleloc = texture->getAttachmentFixedSampleLocations(attachmentImageIndex);
+        if (fixedSampleLocations->valid() && fixedSampleloc != fixedSampleLocations->value())
+        {
+            return false;
+        }
+        else
+        {
+            *fixedSampleLocations = fixedSampleloc;
+        }
+    }
+
+    if (samples->valid())
+    {
+        if (attachment.getSamples() != samples->value())
+        {
+            if (colorAttachment)
+            {
+                // APPLE_framebuffer_multisample, which EXT_draw_buffers refers to, requires that
+                // all color attachments have the same number of samples for the FBO to be complete.
+                return false;
+            }
+            else
+            {
+                // CHROMIUM_framebuffer_mixed_samples allows a framebuffer to be considered complete
+                // when its depth or stencil samples are a multiple of the number of color samples.
+                if (!context->getExtensions().framebufferMixedSamples)
+                {
+                    return false;
+                }
+
+                if ((attachment.getSamples() % std::max(samples->value(), 1)) != 0)
+                {
+                    return false;
+                }
+            }
+        }
+    }
+    else
+    {
+        *samples = attachment.getSamples();
+    }
+
+    return true;
+}
+
+// Needed to index into the attachment arrays/bitsets.
+static_assert(static_cast<size_t>(IMPLEMENTATION_MAX_FRAMEBUFFER_ATTACHMENTS) ==
+                  Framebuffer::DIRTY_BIT_COLOR_ATTACHMENT_MAX,
+              "Framebuffer Dirty bit mismatch");
+static_assert(static_cast<size_t>(IMPLEMENTATION_MAX_FRAMEBUFFER_ATTACHMENTS) ==
+                  Framebuffer::DIRTY_BIT_DEPTH_ATTACHMENT,
+              "Framebuffer Dirty bit mismatch");
+static_assert(static_cast<size_t>(IMPLEMENTATION_MAX_FRAMEBUFFER_ATTACHMENTS + 1) ==
+                  Framebuffer::DIRTY_BIT_STENCIL_ATTACHMENT,
+              "Framebuffer Dirty bit mismatch");
+
+angle::Result InitAttachment(const Context *context, FramebufferAttachment *attachment)
+{
+    ASSERT(attachment->isAttached());
+    if (attachment->initState() == InitState::MayNeedInit)
+    {
+        ANGLE_TRY(attachment->initializeContents(context));
+    }
+    return angle::Result::Continue;
+}
+
+bool IsColorMaskedOut(const BlendState &blend)
+{
+    return (!blend.colorMaskRed && !blend.colorMaskGreen && !blend.colorMaskBlue &&
+            !blend.colorMaskAlpha);
+}
+
+bool IsDepthMaskedOut(const DepthStencilState &depthStencil)
+{
+    return !depthStencil.depthMask;
+}
+
+bool IsStencilMaskedOut(const DepthStencilState &depthStencil)
+{
+    return ((depthStencil.stencilMask & depthStencil.stencilWritemask) == 0);
+}
+
+bool IsClearBufferMaskedOut(const Context *context, GLenum buffer)
+{
+    switch (buffer)
+    {
+        case GL_COLOR:
+            return IsColorMaskedOut(context->getState().getBlendState());
+        case GL_DEPTH:
+            return IsDepthMaskedOut(context->getState().getDepthStencilState());
+        case GL_STENCIL:
+            return IsStencilMaskedOut(context->getState().getDepthStencilState());
+        case GL_DEPTH_STENCIL:
+            return IsDepthMaskedOut(context->getState().getDepthStencilState()) &&
+                   IsStencilMaskedOut(context->getState().getDepthStencilState());
+        default:
+            UNREACHABLE();
+            return true;
+    }
+}
+
+}  // anonymous namespace
+
+// This constructor is only used for default framebuffers.
+FramebufferState::FramebufferState()
+    : mId(0),
+      mLabel(),
+      mColorAttachments(1),
+      mDrawBufferStates(1, GL_BACK),
+      mReadBufferState(GL_BACK),
+      mDrawBufferTypeMask(),
+      mDefaultWidth(0),
+      mDefaultHeight(0),
+      mDefaultSamples(0),
+      mDefaultFixedSampleLocations(GL_FALSE),
+      mDefaultLayers(0),
+      mWebGLDepthStencilConsistent(true)
+{
+    ASSERT(mDrawBufferStates.size() > 0);
+    mEnabledDrawBuffers.set(0);
+}
+
+FramebufferState::FramebufferState(const Caps &caps, GLuint id)
+    : mId(id),
+      mLabel(),
+      mColorAttachments(caps.maxColorAttachments),
+      mDrawBufferStates(caps.maxDrawBuffers, GL_NONE),
+      mReadBufferState(GL_COLOR_ATTACHMENT0_EXT),
+      mDrawBufferTypeMask(),
+      mDefaultWidth(0),
+      mDefaultHeight(0),
+      mDefaultSamples(0),
+      mDefaultFixedSampleLocations(GL_FALSE),
+      mDefaultLayers(0),
+      mWebGLDepthStencilConsistent(true)
+{
+    ASSERT(mId != 0);
+    ASSERT(mDrawBufferStates.size() > 0);
+    mDrawBufferStates[0] = GL_COLOR_ATTACHMENT0_EXT;
+}
+
+FramebufferState::~FramebufferState() {}
+
+const std::string &FramebufferState::getLabel()
+{
+    return mLabel;
+}
+
+const FramebufferAttachment *FramebufferState::getAttachment(const Context *context,
+                                                             GLenum attachment) const
+{
+    if (attachment >= GL_COLOR_ATTACHMENT0 && attachment <= GL_COLOR_ATTACHMENT15)
+    {
+        return getColorAttachment(attachment - GL_COLOR_ATTACHMENT0);
+    }
+
+    // WebGL1 allows a developer to query for attachment parameters even when "inconsistant" (i.e.
+    // multiple conflicting attachment points) and requires us to return the framebuffer attachment
+    // associated with WebGL.
+    switch (attachment)
+    {
+        case GL_COLOR:
+        case GL_BACK:
+            return getColorAttachment(0);
+        case GL_DEPTH:
+        case GL_DEPTH_ATTACHMENT:
+            if (context->isWebGL1())
+            {
+                return getWebGLDepthAttachment();
+            }
+            else
+            {
+                return getDepthAttachment();
+            }
+        case GL_STENCIL:
+        case GL_STENCIL_ATTACHMENT:
+            if (context->isWebGL1())
+            {
+                return getWebGLStencilAttachment();
+            }
+            else
+            {
+                return getStencilAttachment();
+            }
+        case GL_DEPTH_STENCIL:
+        case GL_DEPTH_STENCIL_ATTACHMENT:
+            if (context->isWebGL1())
+            {
+                return getWebGLDepthStencilAttachment();
+            }
+            else
+            {
+                return getDepthStencilAttachment();
+            }
+        default:
+            UNREACHABLE();
+            return nullptr;
+    }
+}
+
+size_t FramebufferState::getReadIndex() const
+{
+    ASSERT(mReadBufferState == GL_BACK ||
+           (mReadBufferState >= GL_COLOR_ATTACHMENT0 && mReadBufferState <= GL_COLOR_ATTACHMENT15));
+    size_t readIndex = (mReadBufferState == GL_BACK
+                            ? 0
+                            : static_cast<size_t>(mReadBufferState - GL_COLOR_ATTACHMENT0));
+    ASSERT(readIndex < mColorAttachments.size());
+    return readIndex;
+}
+
+const FramebufferAttachment *FramebufferState::getReadAttachment() const
+{
+    if (mReadBufferState == GL_NONE)
+    {
+        return nullptr;
+    }
+    size_t readIndex = getReadIndex();
+    return mColorAttachments[readIndex].isAttached() ? &mColorAttachments[readIndex] : nullptr;
+}
+
+const FramebufferAttachment *FramebufferState::getFirstNonNullAttachment() const
+{
+    auto *colorAttachment = getFirstColorAttachment();
+    if (colorAttachment)
+    {
+        return colorAttachment;
+    }
+    return getDepthOrStencilAttachment();
+}
+
+const FramebufferAttachment *FramebufferState::getFirstColorAttachment() const
+{
+    for (const FramebufferAttachment &colorAttachment : mColorAttachments)
+    {
+        if (colorAttachment.isAttached())
+        {
+            return &colorAttachment;
+        }
+    }
+
+    return nullptr;
+}
+
+const FramebufferAttachment *FramebufferState::getDepthOrStencilAttachment() const
+{
+    if (mDepthAttachment.isAttached())
+    {
+        return &mDepthAttachment;
+    }
+    if (mStencilAttachment.isAttached())
+    {
+        return &mStencilAttachment;
+    }
+    return nullptr;
+}
+
+const FramebufferAttachment *FramebufferState::getStencilOrDepthStencilAttachment() const
+{
+    if (mStencilAttachment.isAttached())
+    {
+        return &mStencilAttachment;
+    }
+    return getDepthStencilAttachment();
+}
+
+const FramebufferAttachment *FramebufferState::getColorAttachment(size_t colorAttachment) const
+{
+    ASSERT(colorAttachment < mColorAttachments.size());
+    return mColorAttachments[colorAttachment].isAttached() ? &mColorAttachments[colorAttachment]
+                                                           : nullptr;
+}
+
+const FramebufferAttachment *FramebufferState::getDepthAttachment() const
+{
+    return mDepthAttachment.isAttached() ? &mDepthAttachment : nullptr;
+}
+
+const FramebufferAttachment *FramebufferState::getWebGLDepthAttachment() const
+{
+    return mWebGLDepthAttachment.isAttached() ? &mWebGLDepthAttachment : nullptr;
+}
+
+const FramebufferAttachment *FramebufferState::getWebGLDepthStencilAttachment() const
+{
+    return mWebGLDepthStencilAttachment.isAttached() ? &mWebGLDepthStencilAttachment : nullptr;
+}
+
+const FramebufferAttachment *FramebufferState::getStencilAttachment() const
+{
+    return mStencilAttachment.isAttached() ? &mStencilAttachment : nullptr;
+}
+
+const FramebufferAttachment *FramebufferState::getWebGLStencilAttachment() const
+{
+    return mWebGLStencilAttachment.isAttached() ? &mWebGLStencilAttachment : nullptr;
+}
+
+const FramebufferAttachment *FramebufferState::getDepthStencilAttachment() const
+{
+    // A valid depth-stencil attachment has the same resource bound to both the
+    // depth and stencil attachment points.
+    if (mDepthAttachment.isAttached() && mStencilAttachment.isAttached() &&
+        mDepthAttachment == mStencilAttachment)
+    {
+        return &mDepthAttachment;
+    }
+
+    return nullptr;
+}
+
+bool FramebufferState::attachmentsHaveSameDimensions() const
+{
+    Optional<Extents> attachmentSize;
+
+    auto hasMismatchedSize = [&attachmentSize](const FramebufferAttachment &attachment) {
+        if (!attachment.isAttached())
+        {
+            return false;
+        }
+
+        if (!attachmentSize.valid())
+        {
+            attachmentSize = attachment.getSize();
+            return false;
+        }
+
+        const auto &prevSize = attachmentSize.value();
+        const auto &curSize  = attachment.getSize();
+        return (curSize.width != prevSize.width || curSize.height != prevSize.height);
+    };
+
+    for (const auto &attachment : mColorAttachments)
+    {
+        if (hasMismatchedSize(attachment))
+        {
+            return false;
+        }
+    }
+
+    if (hasMismatchedSize(mDepthAttachment))
+    {
+        return false;
+    }
+
+    return !hasMismatchedSize(mStencilAttachment);
+}
+
+bool FramebufferState::hasSeparateDepthAndStencilAttachments() const
+{
+    // if we have both a depth and stencil buffer, they must refer to the same object
+    // since we only support packed_depth_stencil and not separate depth and stencil
+    return (getDepthAttachment() != nullptr && getStencilAttachment() != nullptr &&
+            getDepthStencilAttachment() == nullptr);
+}
+
+const FramebufferAttachment *FramebufferState::getDrawBuffer(size_t drawBufferIdx) const
+{
+    ASSERT(drawBufferIdx < mDrawBufferStates.size());
+    if (mDrawBufferStates[drawBufferIdx] != GL_NONE)
+    {
+        // ES3 spec: "If the GL is bound to a draw framebuffer object, the ith buffer listed in bufs
+        // must be COLOR_ATTACHMENTi or NONE"
+        ASSERT(mDrawBufferStates[drawBufferIdx] == GL_COLOR_ATTACHMENT0 + drawBufferIdx ||
+               (drawBufferIdx == 0 && mDrawBufferStates[drawBufferIdx] == GL_BACK));
+
+        if (mDrawBufferStates[drawBufferIdx] == GL_BACK)
+        {
+            return getColorAttachment(0);
+        }
+        else
+        {
+            return getColorAttachment(mDrawBufferStates[drawBufferIdx] - GL_COLOR_ATTACHMENT0);
+        }
+    }
+    else
+    {
+        return nullptr;
+    }
+}
+
+size_t FramebufferState::getDrawBufferCount() const
+{
+    return mDrawBufferStates.size();
+}
+
+bool FramebufferState::colorAttachmentsAreUniqueImages() const
+{
+    for (size_t firstAttachmentIdx = 0; firstAttachmentIdx < mColorAttachments.size();
+         firstAttachmentIdx++)
+    {
+        const FramebufferAttachment &firstAttachment = mColorAttachments[firstAttachmentIdx];
+        if (!firstAttachment.isAttached())
+        {
+            continue;
+        }
+
+        for (size_t secondAttachmentIdx = firstAttachmentIdx + 1;
+             secondAttachmentIdx < mColorAttachments.size(); secondAttachmentIdx++)
+        {
+            const FramebufferAttachment &secondAttachment = mColorAttachments[secondAttachmentIdx];
+            if (!secondAttachment.isAttached())
+            {
+                continue;
+            }
+
+            if (firstAttachment == secondAttachment)
+            {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+bool FramebufferState::hasDepth() const
+{
+    return (mDepthAttachment.isAttached() && mDepthAttachment.getDepthSize() > 0);
+}
+
+bool FramebufferState::hasStencil() const
+{
+    return (mStencilAttachment.isAttached() && mStencilAttachment.getStencilSize() > 0);
+}
+
+bool FramebufferState::isMultiview() const
+{
+    const FramebufferAttachment *attachment = getFirstNonNullAttachment();
+    if (attachment == nullptr)
+    {
+        return false;
+    }
+    return attachment->isMultiview();
+}
+
+int FramebufferState::getBaseViewIndex() const
+{
+    const FramebufferAttachment *attachment = getFirstNonNullAttachment();
+    if (attachment == nullptr)
+    {
+        return GL_NONE;
+    }
+    return attachment->getBaseViewIndex();
+}
+
+Box FramebufferState::getDimensions() const
+{
+    Extents extents = getExtents();
+    return Box(0, 0, 0, extents.width, extents.height, extents.depth);
+}
+
+Extents FramebufferState::getExtents() const
+{
+    ASSERT(attachmentsHaveSameDimensions());
+    ASSERT(getFirstNonNullAttachment() != nullptr);
+    return getFirstNonNullAttachment()->getSize();
+}
+
+Framebuffer::Framebuffer(const Caps &caps, rx::GLImplFactory *factory, GLuint id)
+    : mState(caps, id),
+      mImpl(factory->createFramebuffer(mState)),
+      mCachedStatus(),
+      mDirtyDepthAttachmentBinding(this, DIRTY_BIT_DEPTH_ATTACHMENT),
+      mDirtyStencilAttachmentBinding(this, DIRTY_BIT_STENCIL_ATTACHMENT)
+{
+    ASSERT(mImpl != nullptr);
+    ASSERT(mState.mColorAttachments.size() == static_cast<size_t>(caps.maxColorAttachments));
+
+    for (uint32_t colorIndex = 0;
+         colorIndex < static_cast<uint32_t>(mState.mColorAttachments.size()); ++colorIndex)
+    {
+        mDirtyColorAttachmentBindings.emplace_back(this, DIRTY_BIT_COLOR_ATTACHMENT_0 + colorIndex);
+    }
+}
+
+Framebuffer::Framebuffer(const Context *context, egl::Surface *surface)
+    : mState(),
+      mImpl(surface->getImplementation()->createDefaultFramebuffer(context, mState)),
+      mCachedStatus(GL_FRAMEBUFFER_COMPLETE),
+      mDirtyDepthAttachmentBinding(this, DIRTY_BIT_DEPTH_ATTACHMENT),
+      mDirtyStencilAttachmentBinding(this, DIRTY_BIT_STENCIL_ATTACHMENT)
+{
+    ASSERT(mImpl != nullptr);
+    mDirtyColorAttachmentBindings.emplace_back(this, DIRTY_BIT_COLOR_ATTACHMENT_0);
+
+    setAttachmentImpl(context, GL_FRAMEBUFFER_DEFAULT, GL_BACK, ImageIndex(), surface,
+                      FramebufferAttachment::kDefaultNumViews,
+                      FramebufferAttachment::kDefaultBaseViewIndex, false);
+
+    if (surface->getConfig()->depthSize > 0)
+    {
+        setAttachmentImpl(context, GL_FRAMEBUFFER_DEFAULT, GL_DEPTH, ImageIndex(), surface,
+                          FramebufferAttachment::kDefaultNumViews,
+                          FramebufferAttachment::kDefaultBaseViewIndex, false);
+    }
+
+    if (surface->getConfig()->stencilSize > 0)
+    {
+        setAttachmentImpl(context, GL_FRAMEBUFFER_DEFAULT, GL_STENCIL, ImageIndex(), surface,
+                          FramebufferAttachment::kDefaultNumViews,
+                          FramebufferAttachment::kDefaultBaseViewIndex, false);
+    }
+    SetComponentTypeMask(getDrawbufferWriteType(0), 0, &mState.mDrawBufferTypeMask);
+
+    // Ensure the backend has a chance to synchronize its content for a new backbuffer.
+    mDirtyBits.set(DIRTY_BIT_COLOR_BUFFER_CONTENTS_0);
+}
+
+Framebuffer::Framebuffer(rx::GLImplFactory *factory)
+    : mState(),
+      mImpl(factory->createFramebuffer(mState)),
+      mCachedStatus(GL_FRAMEBUFFER_UNDEFINED_OES),
+      mDirtyDepthAttachmentBinding(this, DIRTY_BIT_DEPTH_ATTACHMENT),
+      mDirtyStencilAttachmentBinding(this, DIRTY_BIT_STENCIL_ATTACHMENT)
+{
+    mDirtyColorAttachmentBindings.emplace_back(this, DIRTY_BIT_COLOR_ATTACHMENT_0);
+    SetComponentTypeMask(getDrawbufferWriteType(0), 0, &mState.mDrawBufferTypeMask);
+}
+
+Framebuffer::~Framebuffer()
+{
+    SafeDelete(mImpl);
+}
+
+void Framebuffer::onDestroy(const Context *context)
+{
+    for (auto &attachment : mState.mColorAttachments)
+    {
+        attachment.detach(context);
+    }
+    mState.mDepthAttachment.detach(context);
+    mState.mStencilAttachment.detach(context);
+    mState.mWebGLDepthAttachment.detach(context);
+    mState.mWebGLStencilAttachment.detach(context);
+    mState.mWebGLDepthStencilAttachment.detach(context);
+
+    mImpl->destroy(context);
+}
+
+void Framebuffer::setLabel(const Context *context, const std::string &label)
+{
+    mState.mLabel = label;
+}
+
+const std::string &Framebuffer::getLabel() const
+{
+    return mState.mLabel;
+}
+
+bool Framebuffer::detachTexture(const Context *context, GLuint textureId)
+{
+    return detachResourceById(context, GL_TEXTURE, textureId);
+}
+
+bool Framebuffer::detachRenderbuffer(const Context *context, GLuint renderbufferId)
+{
+    return detachResourceById(context, GL_RENDERBUFFER, renderbufferId);
+}
+
+bool Framebuffer::detachResourceById(const Context *context, GLenum resourceType, GLuint resourceId)
+{
+    bool found = false;
+
+    for (size_t colorIndex = 0; colorIndex < mState.mColorAttachments.size(); ++colorIndex)
+    {
+        if (detachMatchingAttachment(context, &mState.mColorAttachments[colorIndex], resourceType,
+                                     resourceId))
+        {
+            found = true;
+        }
+    }
+
+    if (context->isWebGL1())
+    {
+        const std::array<FramebufferAttachment *, 3> attachments = {
+            {&mState.mWebGLDepthStencilAttachment, &mState.mWebGLDepthAttachment,
+             &mState.mWebGLStencilAttachment}};
+        for (FramebufferAttachment *attachment : attachments)
+        {
+            if (detachMatchingAttachment(context, attachment, resourceType, resourceId))
+            {
+                found = true;
+            }
+        }
+    }
+    else
+    {
+        if (detachMatchingAttachment(context, &mState.mDepthAttachment, resourceType, resourceId))
+        {
+            found = true;
+        }
+        if (detachMatchingAttachment(context, &mState.mStencilAttachment, resourceType, resourceId))
+        {
+            found = true;
+        }
+    }
+
+    return found;
+}
+
+bool Framebuffer::detachMatchingAttachment(const Context *context,
+                                           FramebufferAttachment *attachment,
+                                           GLenum matchType,
+                                           GLuint matchId)
+{
+    if (attachment->isAttached() && attachment->type() == matchType && attachment->id() == matchId)
+    {
+        // We go through resetAttachment to make sure that all the required bookkeeping will be done
+        // such as updating enabled draw buffer state.
+        resetAttachment(context, attachment->getBinding());
+        return true;
+    }
+
+    return false;
+}
+
+const FramebufferAttachment *Framebuffer::getColorAttachment(size_t colorAttachment) const
+{
+    return mState.getColorAttachment(colorAttachment);
+}
+
+const FramebufferAttachment *Framebuffer::getDepthAttachment() const
+{
+    return mState.getDepthAttachment();
+}
+
+const FramebufferAttachment *Framebuffer::getStencilAttachment() const
+{
+    return mState.getStencilAttachment();
+}
+
+const FramebufferAttachment *Framebuffer::getDepthStencilAttachment() const
+{
+    return mState.getDepthStencilAttachment();
+}
+
+const FramebufferAttachment *Framebuffer::getDepthOrStencilAttachment() const
+{
+    return mState.getDepthOrStencilAttachment();
+}
+
+const FramebufferAttachment *Framebuffer::getStencilOrDepthStencilAttachment() const
+{
+    return mState.getStencilOrDepthStencilAttachment();
+}
+
+const FramebufferAttachment *Framebuffer::getReadColorAttachment() const
+{
+    return mState.getReadAttachment();
+}
+
+GLenum Framebuffer::getReadColorAttachmentType() const
+{
+    const FramebufferAttachment *readAttachment = mState.getReadAttachment();
+    return (readAttachment != nullptr ? readAttachment->type() : GL_NONE);
+}
+
+const FramebufferAttachment *Framebuffer::getFirstColorAttachment() const
+{
+    return mState.getFirstColorAttachment();
+}
+
+const FramebufferAttachment *Framebuffer::getFirstNonNullAttachment() const
+{
+    return mState.getFirstNonNullAttachment();
+}
+
+const FramebufferAttachment *Framebuffer::getAttachment(const Context *context,
+                                                        GLenum attachment) const
+{
+    return mState.getAttachment(context, attachment);
+}
+
+size_t Framebuffer::getDrawbufferStateCount() const
+{
+    return mState.mDrawBufferStates.size();
+}
+
+GLenum Framebuffer::getDrawBufferState(size_t drawBuffer) const
+{
+    ASSERT(drawBuffer < mState.mDrawBufferStates.size());
+    return mState.mDrawBufferStates[drawBuffer];
+}
+
+const std::vector<GLenum> &Framebuffer::getDrawBufferStates() const
+{
+    return mState.getDrawBufferStates();
+}
+
+void Framebuffer::setDrawBuffers(size_t count, const GLenum *buffers)
+{
+    auto &drawStates = mState.mDrawBufferStates;
+
+    ASSERT(count <= drawStates.size());
+    std::copy(buffers, buffers + count, drawStates.begin());
+    std::fill(drawStates.begin() + count, drawStates.end(), GL_NONE);
+    mDirtyBits.set(DIRTY_BIT_DRAW_BUFFERS);
+
+    mState.mEnabledDrawBuffers.reset();
+    mState.mDrawBufferTypeMask.reset();
+
+    for (size_t index = 0; index < count; ++index)
+    {
+        SetComponentTypeMask(getDrawbufferWriteType(index), index, &mState.mDrawBufferTypeMask);
+
+        if (drawStates[index] != GL_NONE && mState.mColorAttachments[index].isAttached())
+        {
+            mState.mEnabledDrawBuffers.set(index);
+        }
+    }
+}
+
+const FramebufferAttachment *Framebuffer::getDrawBuffer(size_t drawBuffer) const
+{
+    return mState.getDrawBuffer(drawBuffer);
+}
+
+ComponentType Framebuffer::getDrawbufferWriteType(size_t drawBuffer) const
+{
+    const FramebufferAttachment *attachment = mState.getDrawBuffer(drawBuffer);
+    if (attachment == nullptr)
+    {
+        return ComponentType::NoType;
+    }
+
+    GLenum componentType = attachment->getFormat().info->componentType;
+    switch (componentType)
+    {
+        case GL_INT:
+            return ComponentType::Int;
+        case GL_UNSIGNED_INT:
+            return ComponentType::UnsignedInt;
+
+        default:
+            return ComponentType::Float;
+    }
+}
+
+ComponentTypeMask Framebuffer::getDrawBufferTypeMask() const
+{
+    return mState.mDrawBufferTypeMask;
+}
+
+DrawBufferMask Framebuffer::getDrawBufferMask() const
+{
+    return mState.mEnabledDrawBuffers;
+}
+
+bool Framebuffer::hasEnabledDrawBuffer() const
+{
+    for (size_t drawbufferIdx = 0; drawbufferIdx < mState.mDrawBufferStates.size(); ++drawbufferIdx)
+    {
+        if (getDrawBuffer(drawbufferIdx) != nullptr)
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+GLenum Framebuffer::getReadBufferState() const
+{
+    return mState.mReadBufferState;
+}
+
+void Framebuffer::setReadBuffer(GLenum buffer)
+{
+    ASSERT(buffer == GL_BACK || buffer == GL_NONE ||
+           (buffer >= GL_COLOR_ATTACHMENT0 &&
+            (buffer - GL_COLOR_ATTACHMENT0) < mState.mColorAttachments.size()));
+    mState.mReadBufferState = buffer;
+    mDirtyBits.set(DIRTY_BIT_READ_BUFFER);
+}
+
+size_t Framebuffer::getNumColorAttachments() const
+{
+    return mState.mColorAttachments.size();
+}
+
+bool Framebuffer::hasDepth() const
+{
+    return mState.hasDepth();
+}
+
+bool Framebuffer::hasStencil() const
+{
+    return mState.hasStencil();
+}
+
+bool Framebuffer::usingExtendedDrawBuffers() const
+{
+    for (size_t drawbufferIdx = 1; drawbufferIdx < mState.mDrawBufferStates.size(); ++drawbufferIdx)
+    {
+        if (getDrawBuffer(drawbufferIdx) != nullptr)
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+void Framebuffer::invalidateCompletenessCache()
+{
+    if (mState.mId != 0)
+    {
+        mCachedStatus.reset();
+    }
+    onStateChange(angle::SubjectMessage::DirtyBitsFlagged);
+}
+
+GLenum Framebuffer::checkStatusImpl(const Context *context)
+{
+    ASSERT(!isDefault());
+    ASSERT(hasAnyDirtyBit() || !mCachedStatus.valid());
+
+    mCachedStatus = checkStatusWithGLFrontEnd(context);
+
+    if (mCachedStatus.value() == GL_FRAMEBUFFER_COMPLETE)
+    {
+        // We can skip syncState on several back-ends.
+        if (mImpl->shouldSyncStateBeforeCheckStatus())
+        {
+            angle::Result err = syncState(context);
+            if (err != angle::Result::Continue)
+            {
+                return 0;
+            }
+        }
+
+        if (!mImpl->checkStatus(context))
+        {
+            mCachedStatus = GL_FRAMEBUFFER_UNSUPPORTED;
+        }
+    }
+
+    return mCachedStatus.value();
+}
+
+GLenum Framebuffer::checkStatusWithGLFrontEnd(const Context *context)
+{
+    const State &state = context->getState();
+
+    ASSERT(mState.mId != 0);
+
+    bool hasAttachments = false;
+    Optional<unsigned int> colorbufferSize;
+    Optional<int> samples;
+    Optional<bool> fixedSampleLocations;
+    bool hasRenderbuffer = false;
+
+    const FramebufferAttachment *firstAttachment = getFirstNonNullAttachment();
+
+    Optional<bool> isLayered;
+    Optional<TextureType> colorAttachmentsTextureType;
+
+    for (const FramebufferAttachment &colorAttachment : mState.mColorAttachments)
+    {
+        if (colorAttachment.isAttached())
+        {
+            if (!CheckAttachmentCompleteness(context, colorAttachment))
+            {
+                return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
+            }
+
+            const InternalFormat &format = *colorAttachment.getFormat().info;
+            if (format.depthBits > 0 || format.stencilBits > 0)
+            {
+                return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
+            }
+
+            if (!CheckAttachmentSampleCompleteness(context, colorAttachment, true, &samples,
+                                                   &fixedSampleLocations))
+            {
+                return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE;
+            }
+
+            // in GLES 2.0, all color attachments attachments must have the same number of bitplanes
+            // in GLES 3.0, there is no such restriction
+            if (state.getClientMajorVersion() < 3)
+            {
+                if (colorbufferSize.valid())
+                {
+                    if (format.pixelBytes != colorbufferSize.value())
+                    {
+                        return GL_FRAMEBUFFER_UNSUPPORTED;
+                    }
+                }
+                else
+                {
+                    colorbufferSize = format.pixelBytes;
+                }
+            }
+
+            if (!CheckMultiviewStateMatchesForCompleteness(firstAttachment, &colorAttachment))
+            {
+                return GL_FRAMEBUFFER_INCOMPLETE_VIEW_TARGETS_OVR;
+            }
+
+            hasRenderbuffer = hasRenderbuffer || (colorAttachment.type() == GL_RENDERBUFFER);
+
+            if (!hasAttachments)
+            {
+                isLayered = colorAttachment.isLayered();
+                if (isLayered.value())
+                {
+                    colorAttachmentsTextureType = colorAttachment.getTextureImageIndex().getType();
+                }
+                hasAttachments = true;
+            }
+            else
+            {
+                // [EXT_geometry_shader] section 9.4.1, "Framebuffer Completeness"
+                // If any framebuffer attachment is layered, all populated attachments
+                // must be layered. Additionally, all populated color attachments must
+                // be from textures of the same target. {FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS_EXT }
+                ASSERT(isLayered.valid());
+                if (isLayered.value() != colorAttachment.isLayered())
+                {
+                    return GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS_EXT;
+                }
+                else if (isLayered.value())
+                {
+                    ASSERT(colorAttachmentsTextureType.valid());
+                    if (colorAttachmentsTextureType.value() !=
+                        colorAttachment.getTextureImageIndex().getType())
+                    {
+                        return GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS_EXT;
+                    }
+                }
+            }
+        }
+    }
+
+    const FramebufferAttachment &depthAttachment = mState.mDepthAttachment;
+    if (depthAttachment.isAttached())
+    {
+        if (!CheckAttachmentCompleteness(context, depthAttachment))
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
+        }
+
+        const InternalFormat &format = *depthAttachment.getFormat().info;
+        if (format.depthBits == 0)
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
+        }
+
+        if (!CheckAttachmentSampleCompleteness(context, depthAttachment, false, &samples,
+                                               &fixedSampleLocations))
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE;
+        }
+
+        if (!CheckMultiviewStateMatchesForCompleteness(firstAttachment, &depthAttachment))
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_VIEW_TARGETS_OVR;
+        }
+
+        hasRenderbuffer = hasRenderbuffer || (depthAttachment.type() == GL_RENDERBUFFER);
+
+        if (!hasAttachments)
+        {
+            isLayered      = depthAttachment.isLayered();
+            hasAttachments = true;
+        }
+        else
+        {
+            // [EXT_geometry_shader] section 9.4.1, "Framebuffer Completeness"
+            // If any framebuffer attachment is layered, all populated attachments
+            // must be layered. {FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS_EXT }
+            ASSERT(isLayered.valid());
+            if (isLayered.value() != depthAttachment.isLayered())
+            {
+                return GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS_EXT;
+            }
+        }
+    }
+
+    const FramebufferAttachment &stencilAttachment = mState.mStencilAttachment;
+    if (stencilAttachment.isAttached())
+    {
+        if (!CheckAttachmentCompleteness(context, stencilAttachment))
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
+        }
+
+        const InternalFormat &format = *stencilAttachment.getFormat().info;
+        if (format.stencilBits == 0)
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
+        }
+
+        if (!CheckAttachmentSampleCompleteness(context, stencilAttachment, false, &samples,
+                                               &fixedSampleLocations))
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE;
+        }
+
+        if (!CheckMultiviewStateMatchesForCompleteness(firstAttachment, &stencilAttachment))
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_VIEW_TARGETS_OVR;
+        }
+
+        hasRenderbuffer = hasRenderbuffer || (stencilAttachment.type() == GL_RENDERBUFFER);
+
+        if (!hasAttachments)
+        {
+            hasAttachments = true;
+        }
+        else
+        {
+            // [EXT_geometry_shader] section 9.4.1, "Framebuffer Completeness"
+            // If any framebuffer attachment is layered, all populated attachments
+            // must be layered.
+            // {FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS_EXT }
+            ASSERT(isLayered.valid());
+            if (isLayered.value() != stencilAttachment.isLayered())
+            {
+                return GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS_EXT;
+            }
+        }
+    }
+
+    // Starting from ES 3.0 stencil and depth, if present, should be the same image
+    if (state.getClientMajorVersion() >= 3 && depthAttachment.isAttached() &&
+        stencilAttachment.isAttached() && stencilAttachment != depthAttachment)
+    {
+        return GL_FRAMEBUFFER_UNSUPPORTED;
+    }
+
+    // Special additional validation for WebGL 1 DEPTH/STENCIL/DEPTH_STENCIL.
+    if (state.isWebGL1())
+    {
+        if (!mState.mWebGLDepthStencilConsistent)
+        {
+            return GL_FRAMEBUFFER_UNSUPPORTED;
+        }
+
+        if (mState.mWebGLDepthStencilAttachment.isAttached())
+        {
+            if (mState.mWebGLDepthStencilAttachment.getDepthSize() == 0 ||
+                mState.mWebGLDepthStencilAttachment.getStencilSize() == 0)
+            {
+                return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
+            }
+
+            if (!CheckMultiviewStateMatchesForCompleteness(firstAttachment,
+                                                           &mState.mWebGLDepthStencilAttachment))
+            {
+                return GL_FRAMEBUFFER_INCOMPLETE_VIEW_TARGETS_OVR;
+            }
+        }
+        else if (mState.mStencilAttachment.isAttached() &&
+                 mState.mStencilAttachment.getDepthSize() > 0)
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
+        }
+        else if (mState.mDepthAttachment.isAttached() &&
+                 mState.mDepthAttachment.getStencilSize() > 0)
+        {
+            return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
+        }
+    }
+
+    // ES3.1(section 9.4) requires that if no image is attached to the framebuffer, and either the
+    // value of the framebuffer's FRAMEBUFFER_DEFAULT_WIDTH or FRAMEBUFFER_DEFAULT_HEIGHT parameters
+    // is zero, the framebuffer is considered incomplete.
+    GLint defaultWidth  = mState.getDefaultWidth();
+    GLint defaultHeight = mState.getDefaultHeight();
+    if (!hasAttachments && (defaultWidth == 0 || defaultHeight == 0))
+    {
+        return GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT;
+    }
+
+    // In ES 2.0 and WebGL, all color attachments must have the same width and height.
+    // In ES 3.0, there is no such restriction.
+    if ((state.getClientMajorVersion() < 3 || state.getExtensions().webglCompatibility) &&
+        !mState.attachmentsHaveSameDimensions())
+    {
+        return GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS;
+    }
+
+    // ES3.1(section 9.4) requires that if the attached images are a mix of renderbuffers and
+    // textures, the value of TEXTURE_FIXED_SAMPLE_LOCATIONS must be TRUE for all attached textures.
+    if (fixedSampleLocations.valid() && hasRenderbuffer && !fixedSampleLocations.value())
+    {
+        return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE;
+    }
+
+    // The WebGL conformance tests implicitly define that all framebuffer
+    // attachments must be unique. For example, the same level of a texture can
+    // not be attached to two different color attachments.
+    if (state.getExtensions().webglCompatibility)
+    {
+        if (!mState.colorAttachmentsAreUniqueImages())
+        {
+            return GL_FRAMEBUFFER_UNSUPPORTED;
+        }
+    }
+
+    return GL_FRAMEBUFFER_COMPLETE;
+}
+
+angle::Result Framebuffer::discard(const Context *context, size_t count, const GLenum *attachments)
+{
+    // Back-ends might make the contents of the FBO undefined. In WebGL 2.0, invalidate operations
+    // can be no-ops, so we should probably do that to ensure consistency.
+    // TODO(jmadill): WebGL behaviour, and robust resource init behaviour without WebGL.
+
+    return mImpl->discard(context, count, attachments);
+}
+
+angle::Result Framebuffer::invalidate(const Context *context,
+                                      size_t count,
+                                      const GLenum *attachments)
+{
+    // Back-ends might make the contents of the FBO undefined. In WebGL 2.0, invalidate operations
+    // can be no-ops, so we should probably do that to ensure consistency.
+    // TODO(jmadill): WebGL behaviour, and robust resource init behaviour without WebGL.
+
+    return mImpl->invalidate(context, count, attachments);
+}
+
+bool Framebuffer::partialClearNeedsInit(const Context *context,
+                                        bool color,
+                                        bool depth,
+                                        bool stencil)
+{
+    const auto &glState = context->getState();
+
+    if (!glState.isRobustResourceInitEnabled())
+    {
+        return false;
+    }
+
+    // Scissors can affect clearing.
+    // TODO(jmadill): Check for complete scissor overlap.
+    if (glState.isScissorTestEnabled())
+    {
+        return true;
+    }
+
+    // If colors masked, we must clear before we clear. Do a simple check.
+    // TODO(jmadill): Filter out unused color channels from the test.
+    if (color)
+    {
+        const auto &blend = glState.getBlendState();
+        if (!(blend.colorMaskRed && blend.colorMaskGreen && blend.colorMaskBlue &&
+              blend.colorMaskAlpha))
+        {
+            return true;
+        }
+    }
+
+    const auto &depthStencil = glState.getDepthStencilState();
+    if (stencil && (depthStencil.stencilMask != depthStencil.stencilWritemask ||
+                    depthStencil.stencilBackMask != depthStencil.stencilBackWritemask))
+    {
+        return true;
+    }
+
+    return false;
+}
+
+angle::Result Framebuffer::invalidateSub(const Context *context,
+                                         size_t count,
+                                         const GLenum *attachments,
+                                         const Rectangle &area)
+{
+    // Back-ends might make the contents of the FBO undefined. In WebGL 2.0, invalidate operations
+    // can be no-ops, so we should probably do that to ensure consistency.
+    // TODO(jmadill): Make a invalidate no-op in WebGL 2.0.
+
+    return mImpl->invalidateSub(context, count, attachments, area);
+}
+
+angle::Result Framebuffer::clear(const Context *context, GLbitfield mask)
+{
+    const auto &glState = context->getState();
+    if (glState.isRasterizerDiscardEnabled())
+    {
+        return angle::Result::Continue;
+    }
+
+    // Remove clear bits that are ineffective. An effective clear changes at least one fragment. If
+    // color/depth/stencil masks make the clear ineffective we skip it altogether.
+
+    // If all color channels are masked, don't attempt to clear color.
+    if (context->getState().getBlendState().allChannelsMasked())
+    {
+        mask &= ~GL_COLOR_BUFFER_BIT;
+    }
+
+    // If depth write is disabled, don't attempt to clear depth.
+    if (!context->getState().getDepthStencilState().depthMask)
+    {
+        mask &= ~GL_DEPTH_BUFFER_BIT;
+    }
+
+    // If all stencil bits are masked, don't attempt to clear stencil.
+    if (context->getState().getDepthStencilState().stencilWritemask == 0)
+    {
+        mask &= ~GL_STENCIL_BUFFER_BIT;
+    }
+
+    if (mask != 0)
+    {
+        ANGLE_TRY(mImpl->clear(context, mask));
+    }
+
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::clearBufferfv(const Context *context,
+                                         GLenum buffer,
+                                         GLint drawbuffer,
+                                         const GLfloat *values)
+{
+    if (context->getState().isRasterizerDiscardEnabled() || IsClearBufferMaskedOut(context, buffer))
+    {
+        return angle::Result::Continue;
+    }
+
+    if (buffer == GL_DEPTH)
+    {
+        // If depth write is disabled, don't attempt to clear depth.
+        if (!context->getState().getDepthStencilState().depthMask)
+        {
+            return angle::Result::Continue;
+        }
+    }
+    else
+    {
+        // If all color channels are masked, don't attempt to clear color.
+        if (context->getState().getBlendState().allChannelsMasked())
+        {
+            return angle::Result::Continue;
+        }
+    }
+
+    ANGLE_TRY(mImpl->clearBufferfv(context, buffer, drawbuffer, values));
+
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::clearBufferuiv(const Context *context,
+                                          GLenum buffer,
+                                          GLint drawbuffer,
+                                          const GLuint *values)
+{
+    if (context->getState().isRasterizerDiscardEnabled() || IsClearBufferMaskedOut(context, buffer))
+    {
+        return angle::Result::Continue;
+    }
+
+    // If all color channels are masked, don't attempt to clear color.
+    if (context->getState().getBlendState().allChannelsMasked())
+    {
+        return angle::Result::Continue;
+    }
+
+    ANGLE_TRY(mImpl->clearBufferuiv(context, buffer, drawbuffer, values));
+
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::clearBufferiv(const Context *context,
+                                         GLenum buffer,
+                                         GLint drawbuffer,
+                                         const GLint *values)
+{
+    if (context->getState().isRasterizerDiscardEnabled() || IsClearBufferMaskedOut(context, buffer))
+    {
+        return angle::Result::Continue;
+    }
+
+    if (buffer == GL_STENCIL)
+    {
+        // If all stencil bits are masked, don't attempt to clear stencil.
+        if (context->getState().getDepthStencilState().stencilWritemask == 0)
+        {
+            return angle::Result::Continue;
+        }
+    }
+    else
+    {
+        // If all color channels are masked, don't attempt to clear color.
+        if (context->getState().getBlendState().allChannelsMasked())
+        {
+            return angle::Result::Continue;
+        }
+    }
+
+    ANGLE_TRY(mImpl->clearBufferiv(context, buffer, drawbuffer, values));
+
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::clearBufferfi(const Context *context,
+                                         GLenum buffer,
+                                         GLint drawbuffer,
+                                         GLfloat depth,
+                                         GLint stencil)
+{
+    if (context->getState().isRasterizerDiscardEnabled() || IsClearBufferMaskedOut(context, buffer))
+    {
+        return angle::Result::Continue;
+    }
+
+    bool clearDepth   = context->getState().getDepthStencilState().depthMask;
+    bool clearStencil = context->getState().getDepthStencilState().stencilWritemask != 0;
+
+    if (clearDepth && clearStencil)
+    {
+        ASSERT(buffer == GL_DEPTH_STENCIL);
+        ANGLE_TRY(mImpl->clearBufferfi(context, GL_DEPTH_STENCIL, drawbuffer, depth, stencil));
+    }
+    else if (clearDepth && !clearStencil)
+    {
+        ANGLE_TRY(mImpl->clearBufferfv(context, GL_DEPTH, drawbuffer, &depth));
+    }
+    else if (!clearDepth && clearStencil)
+    {
+        ANGLE_TRY(mImpl->clearBufferiv(context, GL_STENCIL, drawbuffer, &stencil));
+    }
+
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::getImplementationColorReadFormat(const Context *context,
+                                                            GLenum *formatOut)
+{
+    ANGLE_TRY(syncState(context));
+    *formatOut = mImpl->getImplementationColorReadFormat(context);
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::getImplementationColorReadType(const Context *context, GLenum *typeOut)
+{
+    ANGLE_TRY(syncState(context));
+    *typeOut = mImpl->getImplementationColorReadType(context);
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::readPixels(const Context *context,
+                                      const Rectangle &area,
+                                      GLenum format,
+                                      GLenum type,
+                                      void *pixels)
+{
+    ANGLE_TRY(mImpl->readPixels(context, area, format, type, pixels));
+
+    Buffer *unpackBuffer = context->getState().getTargetBuffer(BufferBinding::PixelUnpack);
+    if (unpackBuffer)
+    {
+        unpackBuffer->onPixelPack();
+    }
+
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::blit(const Context *context,
+                                const Rectangle &sourceArea,
+                                const Rectangle &destArea,
+                                GLbitfield mask,
+                                GLenum filter)
+{
+    GLbitfield blitMask = mask;
+
+    // Note that blitting is called against draw framebuffer.
+    // See the code in gl::Context::blitFramebuffer.
+    if ((mask & GL_COLOR_BUFFER_BIT) && !hasEnabledDrawBuffer())
+    {
+        blitMask &= ~GL_COLOR_BUFFER_BIT;
+    }
+
+    if ((mask & GL_STENCIL_BUFFER_BIT) && mState.getStencilAttachment() == nullptr)
+    {
+        blitMask &= ~GL_STENCIL_BUFFER_BIT;
+    }
+
+    if ((mask & GL_DEPTH_BUFFER_BIT) && mState.getDepthAttachment() == nullptr)
+    {
+        blitMask &= ~GL_DEPTH_BUFFER_BIT;
+    }
+
+    if (!blitMask)
+    {
+        return angle::Result::Continue;
+    }
+
+    return mImpl->blit(context, sourceArea, destArea, blitMask, filter);
+}
+
+bool Framebuffer::isDefault() const
+{
+    return id() == 0;
+}
+
+int Framebuffer::getSamples(const Context *context)
+{
+    return (isComplete(context) ? getCachedSamples(context) : 0);
+}
+
+int Framebuffer::getCachedSamples(const Context *context) const
+{
+    ASSERT(mCachedStatus.valid() && mCachedStatus.value() == GL_FRAMEBUFFER_COMPLETE);
+
+    // For a complete framebuffer, all attachments must have the same sample count.
+    // In this case return the first nonzero sample size.
+    const auto *firstNonNullAttachment = mState.getFirstNonNullAttachment();
+    if (firstNonNullAttachment)
+    {
+        ASSERT(firstNonNullAttachment->isAttached());
+        return firstNonNullAttachment->getSamples();
+    }
+
+    // No attachments found.
+    return 0;
+}
+
+angle::Result Framebuffer::getSamplePosition(const Context *context,
+                                             size_t index,
+                                             GLfloat *xy) const
+{
+    ANGLE_TRY(mImpl->getSamplePosition(context, index, xy));
+    return angle::Result::Continue;
+}
+
+bool Framebuffer::hasValidDepthStencil() const
+{
+    return mState.getDepthStencilAttachment() != nullptr;
+}
+
+void Framebuffer::setAttachment(const Context *context,
+                                GLenum type,
+                                GLenum binding,
+                                const ImageIndex &textureIndex,
+                                FramebufferAttachmentObject *resource)
+{
+    setAttachment(context, type, binding, textureIndex, resource,
+                  FramebufferAttachment::kDefaultNumViews,
+                  FramebufferAttachment::kDefaultBaseViewIndex, false);
+}
+
+void Framebuffer::setAttachment(const Context *context,
+                                GLenum type,
+                                GLenum binding,
+                                const ImageIndex &textureIndex,
+                                FramebufferAttachmentObject *resource,
+                                GLsizei numViews,
+                                GLuint baseViewIndex,
+                                bool isMultiview)
+{
+    // Context may be null in unit tests.
+    if (!context || !context->isWebGL1())
+    {
+        setAttachmentImpl(context, type, binding, textureIndex, resource, numViews, baseViewIndex,
+                          isMultiview);
+        return;
+    }
+
+    switch (binding)
+    {
+        case GL_DEPTH_STENCIL:
+        case GL_DEPTH_STENCIL_ATTACHMENT:
+            mState.mWebGLDepthStencilAttachment.attach(context, type, binding, textureIndex,
+                                                       resource, numViews, baseViewIndex,
+                                                       isMultiview);
+            break;
+        case GL_DEPTH:
+        case GL_DEPTH_ATTACHMENT:
+            mState.mWebGLDepthAttachment.attach(context, type, binding, textureIndex, resource,
+                                                numViews, baseViewIndex, isMultiview);
+            break;
+        case GL_STENCIL:
+        case GL_STENCIL_ATTACHMENT:
+            mState.mWebGLStencilAttachment.attach(context, type, binding, textureIndex, resource,
+                                                  numViews, baseViewIndex, isMultiview);
+            break;
+        default:
+            setAttachmentImpl(context, type, binding, textureIndex, resource, numViews,
+                              baseViewIndex, isMultiview);
+            return;
+    }
+
+    commitWebGL1DepthStencilIfConsistent(context, numViews, baseViewIndex, isMultiview);
+}
+
+void Framebuffer::setAttachmentMultiview(const Context *context,
+                                         GLenum type,
+                                         GLenum binding,
+                                         const ImageIndex &textureIndex,
+                                         FramebufferAttachmentObject *resource,
+                                         GLsizei numViews,
+                                         GLint baseViewIndex)
+{
+    setAttachment(context, type, binding, textureIndex, resource, numViews, baseViewIndex, true);
+}
+
+void Framebuffer::commitWebGL1DepthStencilIfConsistent(const Context *context,
+                                                       GLsizei numViews,
+                                                       GLuint baseViewIndex,
+                                                       bool isMultiview)
+{
+    int count = 0;
+
+    std::array<FramebufferAttachment *, 3> attachments = {{&mState.mWebGLDepthStencilAttachment,
+                                                           &mState.mWebGLDepthAttachment,
+                                                           &mState.mWebGLStencilAttachment}};
+    for (FramebufferAttachment *attachment : attachments)
+    {
+        if (attachment->isAttached())
+        {
+            count++;
+        }
+    }
+
+    mState.mWebGLDepthStencilConsistent = (count <= 1);
+    if (!mState.mWebGLDepthStencilConsistent)
+    {
+        // Inconsistent.
+        return;
+    }
+
+    auto getImageIndexIfTextureAttachment = [](const FramebufferAttachment &attachment) {
+        if (attachment.type() == GL_TEXTURE)
+        {
+            return attachment.getTextureImageIndex();
+        }
+        else
+        {
+            return ImageIndex();
+        }
+    };
+
+    if (mState.mWebGLDepthAttachment.isAttached())
+    {
+        const auto &depth = mState.mWebGLDepthAttachment;
+        setAttachmentImpl(context, depth.type(), GL_DEPTH_ATTACHMENT,
+                          getImageIndexIfTextureAttachment(depth), depth.getResource(), numViews,
+                          baseViewIndex, isMultiview);
+        setAttachmentImpl(context, GL_NONE, GL_STENCIL_ATTACHMENT, ImageIndex(), nullptr, numViews,
+                          baseViewIndex, isMultiview);
+    }
+    else if (mState.mWebGLStencilAttachment.isAttached())
+    {
+        const auto &stencil = mState.mWebGLStencilAttachment;
+        setAttachmentImpl(context, GL_NONE, GL_DEPTH_ATTACHMENT, ImageIndex(), nullptr, numViews,
+                          baseViewIndex, isMultiview);
+        setAttachmentImpl(context, stencil.type(), GL_STENCIL_ATTACHMENT,
+                          getImageIndexIfTextureAttachment(stencil), stencil.getResource(),
+                          numViews, baseViewIndex, isMultiview);
+    }
+    else if (mState.mWebGLDepthStencilAttachment.isAttached())
+    {
+        const auto &depthStencil = mState.mWebGLDepthStencilAttachment;
+        setAttachmentImpl(context, depthStencil.type(), GL_DEPTH_ATTACHMENT,
+                          getImageIndexIfTextureAttachment(depthStencil),
+                          depthStencil.getResource(), numViews, baseViewIndex, isMultiview);
+        setAttachmentImpl(context, depthStencil.type(), GL_STENCIL_ATTACHMENT,
+                          getImageIndexIfTextureAttachment(depthStencil),
+                          depthStencil.getResource(), numViews, baseViewIndex, isMultiview);
+    }
+    else
+    {
+        setAttachmentImpl(context, GL_NONE, GL_DEPTH_ATTACHMENT, ImageIndex(), nullptr, numViews,
+                          baseViewIndex, isMultiview);
+        setAttachmentImpl(context, GL_NONE, GL_STENCIL_ATTACHMENT, ImageIndex(), nullptr, numViews,
+                          baseViewIndex, isMultiview);
+    }
+}
+
+void Framebuffer::setAttachmentImpl(const Context *context,
+                                    GLenum type,
+                                    GLenum binding,
+                                    const ImageIndex &textureIndex,
+                                    FramebufferAttachmentObject *resource,
+                                    GLsizei numViews,
+                                    GLuint baseViewIndex,
+                                    bool isMultiview)
+{
+    switch (binding)
+    {
+        case GL_DEPTH_STENCIL:
+        case GL_DEPTH_STENCIL_ATTACHMENT:
+        {
+            // ensure this is a legitimate depth+stencil format
+            FramebufferAttachmentObject *attachmentObj = resource;
+            if (resource)
+            {
+                const Format &format = resource->getAttachmentFormat(binding, textureIndex);
+                if (format.info->depthBits == 0 || format.info->stencilBits == 0)
+                {
+                    // Attaching nullptr detaches the current attachment.
+                    attachmentObj = nullptr;
+                }
+            }
+
+            updateAttachment(context, &mState.mDepthAttachment, DIRTY_BIT_DEPTH_ATTACHMENT,
+                             &mDirtyDepthAttachmentBinding, type, binding, textureIndex,
+                             attachmentObj, numViews, baseViewIndex, isMultiview);
+            updateAttachment(context, &mState.mStencilAttachment, DIRTY_BIT_STENCIL_ATTACHMENT,
+                             &mDirtyStencilAttachmentBinding, type, binding, textureIndex,
+                             attachmentObj, numViews, baseViewIndex, isMultiview);
+            break;
+        }
+
+        case GL_DEPTH:
+        case GL_DEPTH_ATTACHMENT:
+            updateAttachment(context, &mState.mDepthAttachment, DIRTY_BIT_DEPTH_ATTACHMENT,
+                             &mDirtyDepthAttachmentBinding, type, binding, textureIndex, resource,
+                             numViews, baseViewIndex, isMultiview);
+            break;
+
+        case GL_STENCIL:
+        case GL_STENCIL_ATTACHMENT:
+            updateAttachment(context, &mState.mStencilAttachment, DIRTY_BIT_STENCIL_ATTACHMENT,
+                             &mDirtyStencilAttachmentBinding, type, binding, textureIndex, resource,
+                             numViews, baseViewIndex, isMultiview);
+            break;
+
+        case GL_BACK:
+            updateAttachment(context, &mState.mColorAttachments[0], DIRTY_BIT_COLOR_ATTACHMENT_0,
+                             &mDirtyColorAttachmentBindings[0], type, binding, textureIndex,
+                             resource, numViews, baseViewIndex, isMultiview);
+            break;
+
+        default:
+        {
+            size_t colorIndex = binding - GL_COLOR_ATTACHMENT0;
+            ASSERT(colorIndex < mState.mColorAttachments.size());
+            size_t dirtyBit = DIRTY_BIT_COLOR_ATTACHMENT_0 + colorIndex;
+            updateAttachment(context, &mState.mColorAttachments[colorIndex], dirtyBit,
+                             &mDirtyColorAttachmentBindings[colorIndex], type, binding,
+                             textureIndex, resource, numViews, baseViewIndex, isMultiview);
+
+            if (!resource)
+            {
+                mColorAttachmentBits.reset(colorIndex);
+                mFloat32ColorAttachmentBits.reset(colorIndex);
+            }
+            else
+            {
+                mColorAttachmentBits.set(colorIndex);
+                updateFloat32ColorAttachmentBits(
+                    colorIndex, resource->getAttachmentFormat(binding, textureIndex).info);
+            }
+
+            // TODO(jmadill): ASSERT instead of checking the attachment exists in
+            // formsRenderingFeedbackLoopWith
+            bool enabled = (type != GL_NONE && getDrawBufferState(colorIndex) != GL_NONE);
+            mState.mEnabledDrawBuffers.set(colorIndex, enabled);
+            SetComponentTypeMask(getDrawbufferWriteType(colorIndex), colorIndex,
+                                 &mState.mDrawBufferTypeMask);
+        }
+        break;
+    }
+}
+
+void Framebuffer::updateAttachment(const Context *context,
+                                   FramebufferAttachment *attachment,
+                                   size_t dirtyBit,
+                                   angle::ObserverBinding *onDirtyBinding,
+                                   GLenum type,
+                                   GLenum binding,
+                                   const ImageIndex &textureIndex,
+                                   FramebufferAttachmentObject *resource,
+                                   GLsizei numViews,
+                                   GLuint baseViewIndex,
+                                   bool isMultiview)
+{
+    attachment->attach(context, type, binding, textureIndex, resource, numViews, baseViewIndex,
+                       isMultiview);
+    mDirtyBits.set(dirtyBit);
+    mState.mResourceNeedsInit.set(dirtyBit, attachment->initState() == InitState::MayNeedInit);
+    onDirtyBinding->bind(resource);
+
+    invalidateCompletenessCache();
+}
+
+void Framebuffer::resetAttachment(const Context *context, GLenum binding)
+{
+    setAttachment(context, GL_NONE, binding, ImageIndex(), nullptr);
+}
+
+angle::Result Framebuffer::syncState(const Context *context)
+{
+    if (mDirtyBits.any())
+    {
+        mDirtyBitsGuard = mDirtyBits;
+        ANGLE_TRY(mImpl->syncState(context, mDirtyBits));
+        mDirtyBits.reset();
+        mDirtyBitsGuard.reset();
+    }
+    return angle::Result::Continue;
+}
+
+void Framebuffer::onSubjectStateChange(angle::SubjectIndex index, angle::SubjectMessage message)
+{
+    if (message != angle::SubjectMessage::SubjectChanged)
+    {
+        // This can be triggered by SubImage calls for Textures.
+        if (message == angle::SubjectMessage::ContentsChanged)
+        {
+            mDirtyBits.set(DIRTY_BIT_COLOR_BUFFER_CONTENTS_0 + index);
+            onStateChange(angle::SubjectMessage::DirtyBitsFlagged);
+            return;
+        }
+
+        // This can be triggered by the GL back-end TextureGL class.
+        ASSERT(message == angle::SubjectMessage::DirtyBitsFlagged);
+        return;
+    }
+
+    ASSERT(!mDirtyBitsGuard.valid() || mDirtyBitsGuard.value().test(index));
+    mDirtyBits.set(index);
+
+    invalidateCompletenessCache();
+
+    FramebufferAttachment *attachment = getAttachmentFromSubjectIndex(index);
+
+    // Mark the appropriate init flag.
+    mState.mResourceNeedsInit.set(index, attachment->initState() == InitState::MayNeedInit);
+
+    // Update mFloat32ColorAttachmentBits Cache
+    if (index < DIRTY_BIT_COLOR_ATTACHMENT_MAX)
+    {
+        ASSERT(index != DIRTY_BIT_DEPTH_ATTACHMENT);
+        ASSERT(index != DIRTY_BIT_STENCIL_ATTACHMENT);
+        updateFloat32ColorAttachmentBits(index - DIRTY_BIT_COLOR_ATTACHMENT_0,
+                                         attachment->getFormat().info);
+    }
+}
+
+FramebufferAttachment *Framebuffer::getAttachmentFromSubjectIndex(angle::SubjectIndex index)
+{
+    switch (index)
+    {
+        case DIRTY_BIT_DEPTH_ATTACHMENT:
+            return &mState.mDepthAttachment;
+        case DIRTY_BIT_STENCIL_ATTACHMENT:
+            return &mState.mStencilAttachment;
+        default:
+            size_t colorIndex = (index - DIRTY_BIT_COLOR_ATTACHMENT_0);
+            ASSERT(colorIndex < mState.mColorAttachments.size());
+            return &mState.mColorAttachments[colorIndex];
+    }
+}
+
+bool Framebuffer::formsRenderingFeedbackLoopWith(const Context *context) const
+{
+    const State &state     = context->getState();
+    const Program *program = state.getProgram();
+
+    // TODO(jmadill): Default framebuffer feedback loops.
+    if (mState.mId == 0)
+    {
+        return false;
+    }
+
+    const FramebufferAttachment *depth   = getDepthAttachment();
+    const FramebufferAttachment *stencil = getStencilAttachment();
+
+    const bool checkDepth = depth && depth->type() == GL_TEXTURE;
+    // Skip the feedback loop check for stencil if depth/stencil point to the same resource.
+    const bool checkStencil =
+        (stencil && stencil->type() == GL_TEXTURE) && (!depth || *stencil != *depth);
+
+    const gl::ActiveTextureMask &activeTextures   = program->getActiveSamplersMask();
+    const gl::ActiveTexturePointerArray &textures = state.getActiveTexturesCache();
+
+    for (size_t textureUnit : activeTextures)
+    {
+        Texture *texture = textures[textureUnit];
+
+        if (texture == nullptr)
+        {
+            continue;
+        }
+
+        // Depth and stencil attachment form feedback loops
+        // Regardless of if enabled or masked.
+        if (checkDepth)
+        {
+            if (texture->id() == depth->id())
+            {
+                return true;
+            }
+        }
+
+        if (checkStencil)
+        {
+            if (texture->id() == stencil->id())
+            {
+                return true;
+            }
+        }
+
+        // Check if any color attachment forms a feedback loop.
+        for (size_t drawIndex : mColorAttachmentBits)
+        {
+            const FramebufferAttachment &attachment = mState.mColorAttachments[drawIndex];
+            ASSERT(attachment.isAttached());
+
+            if (attachment.isTextureWithId(texture->id()))
+            {
+                // TODO(jmadill): Check for appropriate overlap.
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+bool Framebuffer::formsCopyingFeedbackLoopWith(GLuint copyTextureID,
+                                               GLint copyTextureLevel,
+                                               GLint copyTextureLayer) const
+{
+    if (mState.mId == 0)
+    {
+        // It seems impossible to form a texture copying feedback loop with the default FBO.
+        return false;
+    }
+
+    const FramebufferAttachment *readAttachment = getReadColorAttachment();
+    ASSERT(readAttachment);
+
+    if (readAttachment->isTextureWithId(copyTextureID))
+    {
+        const auto &imageIndex = readAttachment->getTextureImageIndex();
+        if (imageIndex.getLevelIndex() == copyTextureLevel)
+        {
+            // Check 3D/Array texture layers.
+            return !imageIndex.hasLayer() || copyTextureLayer == ImageIndex::kEntireLevel ||
+                   imageIndex.getLayerIndex() == copyTextureLayer;
+        }
+    }
+    return false;
+}
+
+GLint Framebuffer::getDefaultWidth() const
+{
+    return mState.getDefaultWidth();
+}
+
+GLint Framebuffer::getDefaultHeight() const
+{
+    return mState.getDefaultHeight();
+}
+
+GLint Framebuffer::getDefaultSamples() const
+{
+    return mState.getDefaultSamples();
+}
+
+bool Framebuffer::getDefaultFixedSampleLocations() const
+{
+    return mState.getDefaultFixedSampleLocations();
+}
+
+GLint Framebuffer::getDefaultLayers() const
+{
+    return mState.getDefaultLayers();
+}
+
+void Framebuffer::setDefaultWidth(const Context *context, GLint defaultWidth)
+{
+    mState.mDefaultWidth = defaultWidth;
+    mDirtyBits.set(DIRTY_BIT_DEFAULT_WIDTH);
+    invalidateCompletenessCache();
+}
+
+void Framebuffer::setDefaultHeight(const Context *context, GLint defaultHeight)
+{
+    mState.mDefaultHeight = defaultHeight;
+    mDirtyBits.set(DIRTY_BIT_DEFAULT_HEIGHT);
+    invalidateCompletenessCache();
+}
+
+void Framebuffer::setDefaultSamples(const Context *context, GLint defaultSamples)
+{
+    mState.mDefaultSamples = defaultSamples;
+    mDirtyBits.set(DIRTY_BIT_DEFAULT_SAMPLES);
+    invalidateCompletenessCache();
+}
+
+void Framebuffer::setDefaultFixedSampleLocations(const Context *context,
+                                                 bool defaultFixedSampleLocations)
+{
+    mState.mDefaultFixedSampleLocations = defaultFixedSampleLocations;
+    mDirtyBits.set(DIRTY_BIT_DEFAULT_FIXED_SAMPLE_LOCATIONS);
+    invalidateCompletenessCache();
+}
+
+void Framebuffer::setDefaultLayers(GLint defaultLayers)
+{
+    mState.mDefaultLayers = defaultLayers;
+    mDirtyBits.set(DIRTY_BIT_DEFAULT_LAYERS);
+}
+
+GLsizei Framebuffer::getNumViews() const
+{
+    return mState.getNumViews();
+}
+
+GLint Framebuffer::getBaseViewIndex() const
+{
+    return mState.getBaseViewIndex();
+}
+
+bool Framebuffer::isMultiview() const
+{
+    return mState.isMultiview();
+}
+
+bool Framebuffer::readDisallowedByMultiview() const
+{
+    return (mState.isMultiview() && mState.getNumViews() > 1);
+}
+
+angle::Result Framebuffer::ensureClearAttachmentsInitialized(const Context *context,
+                                                             GLbitfield mask)
+{
+    const auto &glState = context->getState();
+    if (!context->isRobustResourceInitEnabled() || glState.isRasterizerDiscardEnabled())
+    {
+        return angle::Result::Continue;
+    }
+
+    const BlendState &blend               = glState.getBlendState();
+    const DepthStencilState &depthStencil = glState.getDepthStencilState();
+
+    bool color   = (mask & GL_COLOR_BUFFER_BIT) != 0 && !IsColorMaskedOut(blend);
+    bool depth   = (mask & GL_DEPTH_BUFFER_BIT) != 0 && !IsDepthMaskedOut(depthStencil);
+    bool stencil = (mask & GL_STENCIL_BUFFER_BIT) != 0 && !IsStencilMaskedOut(depthStencil);
+
+    if (!color && !depth && !stencil)
+    {
+        return angle::Result::Continue;
+    }
+
+    if (partialClearNeedsInit(context, color, depth, stencil))
+    {
+        ANGLE_TRY(ensureDrawAttachmentsInitialized(context));
+    }
+
+    // If the impl encounters an error during a a full (non-partial) clear, the attachments will
+    // still be marked initialized. This simplifies design, allowing this method to be called before
+    // the clear.
+    markDrawAttachmentsInitialized(color, depth, stencil);
+
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::ensureClearBufferAttachmentsInitialized(const Context *context,
+                                                                   GLenum buffer,
+                                                                   GLint drawbuffer)
+{
+    if (!context->isRobustResourceInitEnabled() ||
+        context->getState().isRasterizerDiscardEnabled() || IsClearBufferMaskedOut(context, buffer))
+    {
+        return angle::Result::Continue;
+    }
+
+    if (partialBufferClearNeedsInit(context, buffer))
+    {
+        ANGLE_TRY(ensureBufferInitialized(context, buffer, drawbuffer));
+    }
+
+    // If the impl encounters an error during a a full (non-partial) clear, the attachments will
+    // still be marked initialized. This simplifies design, allowing this method to be called before
+    // the clear.
+    markBufferInitialized(buffer, drawbuffer);
+
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::ensureDrawAttachmentsInitialized(const Context *context)
+{
+    if (!context->isRobustResourceInitEnabled())
+    {
+        return angle::Result::Continue;
+    }
+
+    // Note: we don't actually filter by the draw attachment enum. Just init everything.
+    for (size_t bit : mState.mResourceNeedsInit)
+    {
+        switch (bit)
+        {
+            case DIRTY_BIT_DEPTH_ATTACHMENT:
+                ANGLE_TRY(InitAttachment(context, &mState.mDepthAttachment));
+                break;
+            case DIRTY_BIT_STENCIL_ATTACHMENT:
+                ANGLE_TRY(InitAttachment(context, &mState.mStencilAttachment));
+                break;
+            default:
+                ANGLE_TRY(InitAttachment(context, &mState.mColorAttachments[bit]));
+                break;
+        }
+    }
+
+    mState.mResourceNeedsInit.reset();
+    return angle::Result::Continue;
+}
+
+angle::Result Framebuffer::ensureReadAttachmentsInitialized(const Context *context)
+{
+    ASSERT(context->isRobustResourceInitEnabled());
+
+    if (mState.mResourceNeedsInit.none())
+    {
+        return angle::Result::Continue;
+    }
+
+    if (mState.mReadBufferState != GL_NONE)
+    {
+        size_t readIndex = mState.getReadIndex();
+        if (mState.mResourceNeedsInit[readIndex])
+        {
+            ANGLE_TRY(InitAttachment(context, &mState.mColorAttachments[readIndex]));
+            mState.mResourceNeedsInit.reset(readIndex);
+        }
+    }
+
+    // Conservatively init depth since it can be read by BlitFramebuffer.
+    if (hasDepth())
+    {
+        if (mState.mResourceNeedsInit[DIRTY_BIT_DEPTH_ATTACHMENT])
+        {
+            ANGLE_TRY(InitAttachment(context, &mState.mDepthAttachment));
+            mState.mResourceNeedsInit.reset(DIRTY_BIT_DEPTH_ATTACHMENT);
+        }
+    }
+
+    // Conservatively init stencil since it can be read by BlitFramebuffer.
+    if (hasStencil())
+    {
+        if (mState.mResourceNeedsInit[DIRTY_BIT_STENCIL_ATTACHMENT])
+        {
+            ANGLE_TRY(InitAttachment(context, &mState.mStencilAttachment));
+            mState.mResourceNeedsInit.reset(DIRTY_BIT_STENCIL_ATTACHMENT);
+        }
+    }
+
+    return angle::Result::Continue;
+}
+
+void Framebuffer::markDrawAttachmentsInitialized(bool color, bool depth, bool stencil)
+{
+    // Mark attachments as initialized.
+    if (color)
+    {
+        for (auto colorIndex : mState.mEnabledDrawBuffers)
+        {
+            auto &colorAttachment = mState.mColorAttachments[colorIndex];
+            ASSERT(colorAttachment.isAttached());
+            colorAttachment.setInitState(InitState::Initialized);
+            mState.mResourceNeedsInit.reset(colorIndex);
+        }
+    }
+
+    if (depth && mState.mDepthAttachment.isAttached())
+    {
+        mState.mDepthAttachment.setInitState(InitState::Initialized);
+        mState.mResourceNeedsInit.reset(DIRTY_BIT_DEPTH_ATTACHMENT);
+    }
+
+    if (stencil && mState.mStencilAttachment.isAttached())
+    {
+        mState.mStencilAttachment.setInitState(InitState::Initialized);
+        mState.mResourceNeedsInit.reset(DIRTY_BIT_STENCIL_ATTACHMENT);
+    }
+}
+
+void Framebuffer::markBufferInitialized(GLenum bufferType, GLint bufferIndex)
+{
+    switch (bufferType)
+    {
+        case GL_COLOR:
+        {
+            ASSERT(bufferIndex < static_cast<GLint>(mState.mColorAttachments.size()));
+            if (mState.mColorAttachments[bufferIndex].isAttached())
+            {
+                mState.mColorAttachments[bufferIndex].setInitState(InitState::Initialized);
+                mState.mResourceNeedsInit.reset(bufferIndex);
+            }
+            break;
+        }
+        case GL_DEPTH:
+        {
+            if (mState.mDepthAttachment.isAttached())
+            {
+                mState.mDepthAttachment.setInitState(InitState::Initialized);
+                mState.mResourceNeedsInit.reset(DIRTY_BIT_DEPTH_ATTACHMENT);
+            }
+            break;
+        }
+        case GL_STENCIL:
+        {
+            if (mState.mStencilAttachment.isAttached())
+            {
+                mState.mStencilAttachment.setInitState(InitState::Initialized);
+                mState.mResourceNeedsInit.reset(DIRTY_BIT_STENCIL_ATTACHMENT);
+            }
+            break;
+        }
+        case GL_DEPTH_STENCIL:
+        {
+            if (mState.mDepthAttachment.isAttached())
+            {
+                mState.mDepthAttachment.setInitState(InitState::Initialized);
+                mState.mResourceNeedsInit.reset(DIRTY_BIT_DEPTH_ATTACHMENT);
+            }
+            if (mState.mStencilAttachment.isAttached())
+            {
+                mState.mStencilAttachment.setInitState(InitState::Initialized);
+                mState.mResourceNeedsInit.reset(DIRTY_BIT_STENCIL_ATTACHMENT);
+            }
+            break;
+        }
+        default:
+            UNREACHABLE();
+            break;
+    }
+}
+
+Box Framebuffer::getDimensions() const
+{
+    return mState.getDimensions();
+}
+
+Extents Framebuffer::getExtents() const
+{
+    return mState.getExtents();
+}
+
+angle::Result Framebuffer::ensureBufferInitialized(const Context *context,
+                                                   GLenum bufferType,
+                                                   GLint bufferIndex)
+{
+    ASSERT(context->isRobustResourceInitEnabled());
+
+    if (mState.mResourceNeedsInit.none())
+    {
+        return angle::Result::Continue;
+    }
+
+    switch (bufferType)
+    {
+        case GL_COLOR:
+        {
+            ASSERT(bufferIndex < static_cast<GLint>(mState.mColorAttachments.size()));
+            if (mState.mResourceNeedsInit[bufferIndex])
+            {
+                ANGLE_TRY(InitAttachment(context, &mState.mColorAttachments[bufferIndex]));
+                mState.mResourceNeedsInit.reset(bufferIndex);
+            }
+            break;
+        }
+        case GL_DEPTH:
+        {
+            if (mState.mResourceNeedsInit[DIRTY_BIT_DEPTH_ATTACHMENT])
+            {
+                ANGLE_TRY(InitAttachment(context, &mState.mDepthAttachment));
+                mState.mResourceNeedsInit.reset(DIRTY_BIT_DEPTH_ATTACHMENT);
+            }
+            break;
+        }
+        case GL_STENCIL:
+        {
+            if (mState.mResourceNeedsInit[DIRTY_BIT_STENCIL_ATTACHMENT])
+            {
+                ANGLE_TRY(InitAttachment(context, &mState.mStencilAttachment));
+                mState.mResourceNeedsInit.reset(DIRTY_BIT_STENCIL_ATTACHMENT);
+            }
+            break;
+        }
+        case GL_DEPTH_STENCIL:
+        {
+            if (mState.mResourceNeedsInit[DIRTY_BIT_DEPTH_ATTACHMENT])
+            {
+                ANGLE_TRY(InitAttachment(context, &mState.mDepthAttachment));
+                mState.mResourceNeedsInit.reset(DIRTY_BIT_DEPTH_ATTACHMENT);
+            }
+            if (mState.mResourceNeedsInit[DIRTY_BIT_STENCIL_ATTACHMENT])
+            {
+                ANGLE_TRY(InitAttachment(context, &mState.mStencilAttachment));
+                mState.mResourceNeedsInit.reset(DIRTY_BIT_STENCIL_ATTACHMENT);
+            }
+            break;
+        }
+        default:
+            UNREACHABLE();
+            break;
+    }
+
+    return angle::Result::Continue;
+}
+
+bool Framebuffer::partialBufferClearNeedsInit(const Context *context, GLenum bufferType)
+{
+    if (!context->isRobustResourceInitEnabled() || mState.mResourceNeedsInit.none())
+    {
+        return false;
+    }
+
+    switch (bufferType)
+    {
+        case GL_COLOR:
+            return partialClearNeedsInit(context, true, false, false);
+        case GL_DEPTH:
+            return partialClearNeedsInit(context, false, true, false);
+        case GL_STENCIL:
+            return partialClearNeedsInit(context, false, false, true);
+        case GL_DEPTH_STENCIL:
+            return partialClearNeedsInit(context, false, true, true);
+        default:
+            UNREACHABLE();
+            return false;
+    }
+}
+}  // namespace gl