Attaching an image to many color attachment points is unsupported

gpu/command_buffer/service/framebuffer_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/framebuffer_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/logging.h"
@@ skipping 71 matching lines @@
 
   bool IsTextureAttachment() const override { return false; }
   bool IsRenderbufferAttachment() const override { return true; }
 
   bool IsTexture(TextureRef* /* texture */) const override { return false; }
 
   bool IsRenderbuffer(Renderbuffer* renderbuffer) const override {
     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; }
 
   void DetachFromFramebuffer(Framebuffer* framebuffer) const override {
     // Nothing to do for renderbuffers.
   }
 
   bool IsLayerValid() const override { return true; }
 
@@ skipping 111 matching lines @@
     return texture_ref_->texture()->IsLevelPartiallyCleared(target_, level_);
   }
 
   bool IsTextureAttachment() const override { return true; }
   bool IsRenderbufferAttachment() const override { return false; }
 
   bool IsTexture(TextureRef* texture) const override {
     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()) &&
+          samples_ == other->samples() &&

[Zhenyao Mo, 2016/07/19 20:39:15]

samples should not be part of this. No matter what samples we use, it is still
the same image.

[qiankun, 2016/07/20 08:53:33]

Done.

+          layer_ == other->layer() &&
+          target_ == other->target() &&

[Zhenyao Mo, 2016/07/19 20:39:15]

This makes me think, can you add some test cases in the conformance test to make
sure if we attach different faces of the same cubemap level, or if we attach
different layer of the same 3D image level, they are allowed?

[qiankun, 2016/07/20 08:53:33]

I will add test for this.

+          level_ == other->level();
+    }
+    return false;
+  }
+
   bool IsRenderbuffer(Renderbuffer* /* renderbuffer */) const override {
     return false;
   }
 
   bool Is3D() const override {
     return (target_ == GL_TEXTURE_3D || target_ == GL_TEXTURE_2D_ARRAY);
   }
 
   TextureRef* texture() const {
     return texture_ref_.get();
@@ skipping 183 matching lines @@
     if (it->first >= GL_COLOR_ATTACHMENT0 &&
         it->first < GL_COLOR_ATTACHMENT0 + manager_->max_draw_buffers_) {
       const Attachment* attachment = it->second.get();
       if (!attachment->cleared())
         return true;
     }
   }
   return false;
 }
 
+bool Framebuffer::HasDuplicateColorAttachments() const {
+  for (AttachmentMap::const_iterator it = attachments_.begin();
+       it != attachments_.end(); ++it) {
+    if (it->first >= GL_COLOR_ATTACHMENT0 &&
+        it->first < GL_COLOR_ATTACHMENT0 + manager_->max_draw_buffers_) {

[Zhenyao Mo, 2016/07/19 20:39:15]

max_color_attachments_

[qiankun, 2016/07/20 08:53:33]

That's fine.
I saw in WebGL 2.0 spec max_color_attachments_ must be equal to
max_draw_buffers. 
The usage of these two variables are mixed. See other places in this file.

+      const Attachment* attachment = it->second.get();
+      for (GLenum i = it->first + 1;
+           i < GL_COLOR_ATTACHMENT0 + manager_->max_draw_buffers_; i++) {

[Zhenyao Mo, 2016/07/19 20:39:15]

max_color_attachments_

+        const Attachment* other = GetAttachment(i);
+        if (other && attachment->IsSameAttachment(other)) {
+          return true;
+        }
+      }
+    }
+  }
+  return false;
+}
+
 bool Framebuffer::HasUnclearedIntRenderbufferAttachments() const {
   for (AttachmentMap::const_iterator it = attachments_.begin();
        it != attachments_.end(); ++it) {
     if (!it->second->IsRenderbufferAttachment() || it->second->cleared())
       continue;
     if (GLES2Util::IsIntegerFormat(it->second->internal_format()))
       return true;
   }
   return false;
 }
@@ skipping 568 matching lines @@
 
 bool FramebufferManager::IsComplete(
     Framebuffer* framebuffer) {
   DCHECK(framebuffer);
   return framebuffer->framebuffer_complete_state_count_id() ==
       framebuffer_state_change_count_;
 }
 
 }  // namespace gles2
 }  // namespace gpu