Attaching an image to many color attachment points is unsupported

See Section 5.34 Framebuffer color attachments in WebGL 2.0 spec.

BUG=628861
TEST=gpu_unittests conformance2/rendering/framebuffer-unsupported.html
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2159183002
Cr-Commit-Position: refs/heads/master@{#406613}

gpu/command_buffer/service/feature_info.cc

@@ -211,6 +211,10 @@ bool FeatureInfo::InitializeForTesting() {
   return Initialize(CONTEXT_TYPE_OPENGLES2, DisallowedFeatures());
 }
 
+bool FeatureInfo::InitializeForTesting(ContextType context_type) {
+  return Initialize(context_type, DisallowedFeatures());
+}
+
 bool IsGL_REDSupportedOnFBOs() {
   // Skia uses GL_RED with frame buffers, unfortunately, Mesa claims to support
   // GL_EXT_texture_rg, but it doesn't support it on frame buffers.  To fix

gpu/command_buffer/service/feature_info.h

@@ -110,6 +110,8 @@ class GPU_EXPORT FeatureInfo : public base::RefCounted<FeatureInfo> {
 
   // Helper that defaults to no disallowed features and a GLES2 context.
   bool InitializeForTesting();
+  // Helper that defaults to no disallowed Features.
+  bool InitializeForTesting(ContextType context_type);
   // Helper that defaults to a GLES2 context.
   bool InitializeForTesting(const DisallowedFeatures& disallowed_features);
 

gpu/command_buffer/service/framebuffer_manager.cc

@@ -89,6 +89,15 @@ class RenderbufferAttachment
     return renderbuffer_.get() == renderbuffer;
   }
 
+  bool IsSameAttachment(const Attachment* attachment) const override {
+    if (attachment->IsRenderbufferAttachment()) {
+      const RenderbufferAttachment* other =
+          reinterpret_cast<const RenderbufferAttachment*>(attachment);
+      return IsRenderbuffer(other->renderbuffer());
+    }
+    return false;
+  }
+
   bool Is3D() const override { return false; }
 
   bool CanRenderTo(const FeatureInfo*) const override { return true; }
@@ -220,6 +229,18 @@ class TextureAttachment
     return texture == texture_ref_.get();
   }
 
+  bool IsSameAttachment(const Attachment* attachment) const override {
+    if (attachment->IsTextureAttachment()) {
+      const TextureAttachment* other =
+          reinterpret_cast<const TextureAttachment*>(attachment);
+      return IsTexture(other->texture()) &&
+          layer_ == other->layer() &&
+          target_ == other->target() &&
+          level_ == other->level();
+    }
+    return false;
+  }
+
   bool IsRenderbuffer(Renderbuffer* /* renderbuffer */) const override {
     return false;
   }
@@ -711,6 +732,19 @@ GLenum Framebuffer::IsPossiblyComplete(const FeatureInfo* feature_info) const {
     if (!attachment->CanRenderTo(feature_info)) {
       return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
     }
+
+    // Attaching an image to more than one color attachment point should return
+    // FRAMEBUFFER_UNSUPPORTED.
+    if (it->first >= GL_COLOR_ATTACHMENT0 &&
+        it->first < GL_COLOR_ATTACHMENT0 + manager_->max_color_attachments_) {
+      for (GLenum i = it->first + 1;
+           i < GL_COLOR_ATTACHMENT0 + manager_->max_color_attachments_; i++) {
+        const Attachment* other = GetAttachment(i);
+        if (other && attachment->IsSameAttachment(other)) {
+          return GL_FRAMEBUFFER_UNSUPPORTED;
+        }
+      }
+    }
   }
 
   // This does not mean the framebuffer is actually complete. It just means our

gpu/command_buffer/service/framebuffer_manager.h

@@ -51,8 +51,8 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
     virtual bool IsTextureAttachment() const = 0;
     virtual bool IsRenderbufferAttachment() const = 0;
     virtual bool IsTexture(TextureRef* texture) const = 0;
-    virtual bool IsRenderbuffer(
-        Renderbuffer* renderbuffer) const = 0;
+    virtual bool IsRenderbuffer(Renderbuffer* renderbuffer) const = 0;
+    virtual bool IsSameAttachment(const Attachment* attachment) const = 0;
     virtual bool Is3D() const = 0;
 
     // If it's a 3D texture attachment, return true if

gpu/command_buffer/service/framebuffer_manager_unittest.cc

@@ -1494,6 +1494,23 @@ TEST_F(FramebufferInfoTest, GetStatus) {
 class FramebufferInfoES3Test : public FramebufferInfoTestBase {
  public:
   FramebufferInfoES3Test() : FramebufferInfoTestBase(CONTEXT_TYPE_WEBGL2) {}
+
+ protected:
+  void SetUp() override {
+    InitializeContext("OpenGL ES 3.0", "");
+  }
+
+  void InitializeContext(const char* gl_version, const char* extensions) {
+    GpuServiceTest::SetUpWithGLVersion(gl_version, extensions);
+    TestHelper::SetupFeatureInfoInitExpectationsWithGLVersion(gl_.get(),
+        extensions, "", gl_version);
+    feature_info_->InitializeForTesting(CONTEXT_TYPE_OPENGLES3);
+    decoder_.reset(new MockGLES2Decoder());
+    manager_.CreateFramebuffer(kClient1Id, kService1Id);
+    error_state_.reset(new ::testing::StrictMock<gles2::MockErrorState>());
+    framebuffer_ = manager_.GetFramebuffer(kClient1Id);
+    ASSERT_TRUE(framebuffer_ != NULL);
+  }
 };
 
 TEST_F(FramebufferInfoES3Test, DifferentDimensions) {
@@ -1538,6 +1555,38 @@ TEST_F(FramebufferInfoES3Test, DifferentDimensions) {
             framebuffer_->IsPossiblyComplete(feature_info_.get()));
 }
 
+TEST_F(FramebufferInfoES3Test, DuplicatedAttachments) {
+  const GLuint kTextureClientId = 33;
+  const GLuint kTextureServiceId = 333;
+  const GLenum kTarget = GL_TEXTURE_2D;
+  const GLint kLevel = 0;
+  const GLenum kFormat = GL_RGBA;
+  const GLenum kType = GL_UNSIGNED_BYTE;
+  const GLint kWidth = 16;
+  const GLint kHeight = 32;
+  const GLint kDepth = 1;
+  const GLint kBorder = 0;
+  const GLint kSamples = 0;
+
+  texture_manager_->CreateTexture(kTextureClientId, kTextureServiceId);
+  scoped_refptr<TextureRef> texture(
+      texture_manager_->GetTexture(kTextureClientId));
+  ASSERT_TRUE(texture.get() != nullptr);
+  texture_manager_->SetTarget(texture.get(), GL_TEXTURE_2D);
+  texture_manager_->SetLevelInfo(texture.get(), GL_TEXTURE_2D, kLevel,
+                                 kFormat, kWidth, kHeight, kDepth, kBorder,
+                                 kFormat, kType, gfx::Rect());
+
+  // Check an image is attached to more than one color attachment point
+  // in a framebuffer.
+  framebuffer_->AttachTexture(
+      GL_COLOR_ATTACHMENT0, texture.get(), kTarget, kLevel, kSamples);
+  framebuffer_->AttachTexture(
+      GL_COLOR_ATTACHMENT1, texture.get(), kTarget, kLevel, kSamples);
+  EXPECT_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_UNSUPPORTED),
+      framebuffer_->IsPossiblyComplete(feature_info_.get()));
+}
+
 TEST_F(FramebufferInfoES3Test, ReadBuffer) {
   const GLuint kRenderbufferClientId = 33;
   const GLuint kRenderbufferServiceId = 333;