Implement ReadBuffer functionality.

src/libANGLE/Framebuffer.cpp

@@ -132,14 +132,15 @@ FramebufferAttachment *Framebuffer::getDepthOrStencilbuffer() const
 
 FramebufferAttachment *Framebuffer::getReadColorbuffer() const
 {
-    // Will require more logic if glReadBuffers is supported
-    return mColorbuffers[0];
+    size_t readIndex = (mReadBufferState == GL_BACK ? 0 : static_cast<size_t>(mReadBufferState - GL_COLOR_ATTACHMENT0));
+    ASSERT(readIndex < IMPLEMENTATION_MAX_DRAW_BUFFERS);
+    return mColorbuffers[readIndex];
 }
 
 GLenum Framebuffer::getReadColorbufferType() const
 {
-    // Will require more logic if glReadBuffers is supported
-    return (mColorbuffers[0] ? mColorbuffers[0]->type() : GL_NONE);
+    FramebufferAttachment *readAttachment = getReadColorbuffer();
+    return (readAttachment ? readAttachment->type() : GL_NONE);
 }
 
 FramebufferAttachment *Framebuffer::getFirstColorbuffer() const
@@ -204,6 +205,9 @@ GLenum Framebuffer::getReadBufferState() const
 
 void Framebuffer::setReadBuffer(GLenum buffer)
 {
+    ASSERT(buffer == GL_BACK || buffer == GL_NONE ||
+           (buffer >= GL_COLOR_ATTACHMENT0 &&
+            (buffer - GL_COLOR_ATTACHMENT0) < IMPLEMENTATION_MAX_DRAW_BUFFERS));
     mReadBufferState = buffer;
     mImpl->setReadBuffer(buffer);
 }

src/libANGLE/renderer/d3d/FramebufferD3D.cpp

@@ -207,18 +207,25 @@ gl::Error FramebufferD3D::clearBufferfi(const gl::State &state, GLenum buffer, G
     return clear(state, clearParams);
 }
 
+const gl::FramebufferAttachment *FramebufferD3D::getReadAttachment() const
+{
+    ASSERT(mReadBuffer == GL_BACK || (mReadBuffer >= GL_COLOR_ATTACHMENT0 && mReadBuffer <= GL_COLOR_ATTACHMENT15));
+    size_t readIndex = (mReadBuffer == GL_BACK ? 0 : static_cast<size_t>(mReadBuffer - GL_COLOR_ATTACHMENT0));
+    ASSERT(readIndex < mColorBuffers.size());
+    return mColorBuffers[readIndex];
+}
+
 GLenum FramebufferD3D::getImplementationColorReadFormat() const
 {
-    // Will require more logic if glReadBuffers is supported
-    ASSERT(mReadBuffer == GL_COLOR_ATTACHMENT0 || mReadBuffer == GL_BACK);
+    const gl::FramebufferAttachment *readAttachment = getReadAttachment();
 
-    if (mColorBuffers[0] == nullptr)
+    if (readAttachment == nullptr)
     {
         return GL_NONE;
     }
 
     RenderTargetD3D *attachmentRenderTarget = NULL;
-    gl::Error error = GetAttachmentRenderTarget(mColorBuffers[0], &attachmentRenderTarget);
+    gl::Error error = GetAttachmentRenderTarget(readAttachment, &attachmentRenderTarget);
     if (error.isError())
     {
         return GL_NONE;
@@ -232,16 +239,15 @@ GLenum FramebufferD3D::getImplementationColorReadFormat() const
 
 GLenum FramebufferD3D::getImplementationColorReadType() const
 {
-    // Will require more logic if glReadBuffers is supported
-    ASSERT(mReadBuffer == GL_COLOR_ATTACHMENT0 || mReadBuffer == GL_BACK);
+    const gl::FramebufferAttachment *readAttachment = getReadAttachment();
 
-    if (mColorBuffers[0] == nullptr)
+    if (readAttachment == nullptr)
     {
         return GL_NONE;
     }
 
     RenderTargetD3D *attachmentRenderTarget = NULL;
-    gl::Error error = GetAttachmentRenderTarget(mColorBuffers[0], &attachmentRenderTarget);
+    gl::Error error = GetAttachmentRenderTarget(readAttachment, &attachmentRenderTarget);
     if (error.isError())
     {
         return GL_NONE;

src/libANGLE/renderer/d3d/FramebufferD3D.h

@@ -78,6 +78,7 @@ class FramebufferD3D : public FramebufferImpl
                    GLbitfield mask, GLenum filter, const gl::Framebuffer *sourceFramebuffer) override;
 
     GLenum checkStatus() const override;
+    const gl::FramebufferAttachment *getReadAttachment() const;
 
   protected:
     std::vector<const gl::FramebufferAttachment*> mColorBuffers;

src/libANGLE/renderer/d3d/d3d11/Framebuffer11.cpp

@@ -108,7 +108,7 @@ gl::Error Framebuffer11::readPixels(const gl::Rectangle &area, GLenum format, GL
     ID3D11Texture2D *colorBufferTexture = NULL;
     unsigned int subresourceIndex = 0;
 
-    const gl::FramebufferAttachment *colorbuffer = mColorBuffers[0];
+    const gl::FramebufferAttachment *colorbuffer = getReadAttachment();
     ASSERT(colorbuffer);
 
     gl::Error error = getRenderTargetResource(colorbuffer, &subresourceIndex, &colorBufferTexture);

src/libANGLE/validationES3.cpp

@@ -1228,4 +1228,55 @@ bool ValidateGetUniformuiv(Context *context, GLuint program, GLint location, GLu
     return ValidateGetUniformBase(context, program, location);
 }
 
+bool ValidateReadBuffer(Context *context, GLenum src)
+{
+    if (context->getClientVersion() < 3)
+    {
+        context->recordError(Error(GL_INVALID_OPERATION));
+        return false;
+    }
+
+    Framebuffer *readFBO = context->getState().getReadFramebuffer();
+
+    if (readFBO == nullptr)
+    {
+        context->recordError(gl::Error(GL_INVALID_OPERATION, "No active read framebuffer."));
+        return false;
+    }
+
+    if (src == GL_NONE)
+    {
+        return true;
+    }
+
+    if (src != GL_BACK && (src < GL_COLOR_ATTACHMENT0 || src > GL_COLOR_ATTACHMENT15))
+    {
+        context->recordError(gl::Error(GL_INVALID_ENUM, "Unknown enum for 'src' in ReadBuffer"));
+        return false;
+    }
+
+    if (readFBO->id() == 0)
+    {
+        if (src != GL_BACK)
+        {
+            const char *errorMsg = "'src' must be GL_NONE or GL_BACK when reading from the default framebuffer.";
+            context->recordError(gl::Error(GL_INVALID_OPERATION, errorMsg));
+            return false;
+        }
+    }
+    else
+    {
+        GLuint drawBuffer = static_cast<GLuint>(src - GL_COLOR_ATTACHMENT0);
+
+        if (drawBuffer >= context->getCaps().maxDrawBuffers)
+        {
+            const char *errorMsg = "'src' is greater than MAX_DRAW_BUFFERS.";
+            context->recordError(gl::Error(GL_INVALID_OPERATION, errorMsg));
+            return false;
+        }
+    }
+
+    return true;
+}
+
 }

src/libANGLE/validationES3.h

@@ -42,6 +42,8 @@ bool ValidateClearBuffer(Context *context);
 
 bool ValidateGetUniformuiv(Context *context, GLuint program, GLint location, GLuint* params);
 
+bool ValidateReadBuffer(Context *context, GLenum mode);
+
 }
 
 #endif // LIBANGLE_VALIDATION_ES3_H_

src/libGLESv2/entry_points_gles_3_0.cpp

@@ -35,14 +35,13 @@ void GL_APIENTRY ReadBuffer(GLenum mode)
     Context *context = GetValidGlobalContext();
     if (context)
     {
-        if (context->getClientVersion() < 3)
+        if (!ValidateReadBuffer(context, mode))
         {
-            context->recordError(Error(GL_INVALID_OPERATION));
             return;
         }
 
-        // glReadBuffer
-        UNIMPLEMENTED();
+        Framebuffer *readFBO = context->getState().getReadFramebuffer();
+        readFBO->setReadBuffer(mode);
     }
 }