Validate fbo color image format and fragment shader output variable type.

gpu/command_buffer/service/framebuffer_manager.h

Index: gpu/command_buffer/service/framebuffer_manager.h
diff --git a/gpu/command_buffer/service/framebuffer_manager.h b/gpu/command_buffer/service/framebuffer_manager.h
index 2337843f68ef929b447efbf1cb4c81f7a4658d44..2cf4cde2b979c48b9b35133b667564b22cc88122 100644
--- a/gpu/command_buffer/service/framebuffer_manager.h
+++ b/gpu/command_buffer/service/framebuffer_manager.h
@@ -16,6 +16,7 @@
 #include "base/memory/ref_counted.h"
 #include "gpu/command_buffer/service/context_group.h"
 #include "gpu/command_buffer/service/gl_utils.h"
+#include "gpu/command_buffer/service/shader_manager.h"
 #include "gpu/gpu_export.h"
 
 namespace gpu {
@@ -178,11 +179,20 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
   // If a color buffer is attached to GL_COLOR_ATTACHMENTi, enable that
   // draw buffer for glClear().
   // Return true if the DrawBuffers() is actually called.
-  bool PrepareDrawBuffersForClear() const;
+  bool PrepareDrawBuffersForClearingUninitializedAttachments() const;
 
-  // Restore draw buffers states that have been changed in
-  // PrepareDrawBuffersForClear().
-  void RestoreDrawBuffersAfterClear() const;
+  // Restore |adjusted_draw_buffers_|.
+  void RestoreDrawBuffers() const;
+
+  // Checks if a draw buffer's format and its corresponding fragment shader
+  // output's type are compatible, i.e., a signed integer typed variable is
+  // incompatible with a float or unsigned integer buffer.
+  // If it's for Clear(), then |fragment_output_base_types| is nullptr.
+  // Return false if incompaticle.
+  // Otherwise, filter out the draw buffers that are not written to but are not
+  // NONE through DrawBuffers, to be on the safe side. Return true.
+  bool ValidateAndAdjustDrawBuffers(
+      const ShaderVariableBaseType* fragment_output_base_types);
 
   // Return true if any draw buffers has an alpha channel.
   bool HasAlphaMRT() const;
@@ -199,6 +209,10 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
     return read_buffer_;
   }
 
+  const ShaderVariableBaseType* GetColorAttachmentBaseTypes() const {
+    return color_attachment_base_types_.get();
+  }
+
  private:
   friend class FramebufferManager;
   friend class base::RefCounted<Framebuffer>;
@@ -213,6 +227,7 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
     bool cleared);
 
   void MarkAsComplete(unsigned state_id) {
+    UpdateColorAttachmentBaseTypes();
     framebuffer_complete_state_count_id_ = state_id;
   }
 
@@ -220,6 +235,13 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
     return framebuffer_complete_state_count_id_;
   }
 
+  // Cache color attachments' base types (FLOAT, INT, UINT) for optimization
+  // purpose. If an attachment point has no image, it's set as UNDEFINED_TYPE.
+  // This call is only valid on a complete fbo.
+  void UpdateColorAttachmentBaseTypes();
+
+  void ResetColorAttachmentBaseTypes();
+
   // The managers that owns this.
   FramebufferManager* manager_;
 
@@ -238,8 +260,17 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
   typedef base::hash_map<GLenum, scoped_refptr<Attachment> > AttachmentMap;
   AttachmentMap attachments_;
 
+  // User's draw buffers setting through DrawBuffers() call.
   std::unique_ptr<GLenum[]> draw_buffers_;
 
+  // If a draw buffer does not have an image, or it has no corresponding
+  // fragment shader output variable, it might be filtered out as NONE.
+  // Note that the actually draw buffers setting sent to the driver is always
+  // consistent with |adjusted_draw_buffers_|, not |draw_buffers_|.
+  std::unique_ptr<GLenum[]> adjusted_draw_buffers_;
+
+  std::unique_ptr<ShaderVariableBaseType[]> color_attachment_base_types_;
+
   GLenum read_buffer_;
 
   DISALLOW_COPY_AND_ASSIGN(Framebuffer);