command_buffer: Implement EXT_blend_func_extended

gpu/command_buffer/service/context_group.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/context_group.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 50 matching lines @@
       bind_generates_resource_(bind_generates_resource),
       max_vertex_attribs_(0u),
       max_texture_units_(0u),
       max_texture_image_units_(0u),
       max_vertex_texture_image_units_(0u),
       max_fragment_uniform_vectors_(0u),
       max_varying_vectors_(0u),
       max_vertex_uniform_vectors_(0u),
       max_color_attachments_(1u),
       max_draw_buffers_(1u),
+      max_dual_source_draw_buffers_(0u),
       program_cache_(NULL),
       feature_info_(feature_info) {
   {
     if (!mailbox_manager_.get())
       mailbox_manager_ = new MailboxManagerImpl;
     if (!subscription_ref_set_.get())
       subscription_ref_set_ = new SubscriptionRefSet();
     if (!pending_valuebuffer_state_.get())
       pending_valuebuffer_state_ = new ValueStateMap();
     if (!feature_info.get())
@@ skipping 56 matching lines @@
   }
 
   if (feature_info_->feature_flags().ext_draw_buffers) {
     GetIntegerv(GL_MAX_COLOR_ATTACHMENTS_EXT, &max_color_attachments_);
     if (max_color_attachments_ < 1)
       max_color_attachments_ = 1;
     GetIntegerv(GL_MAX_DRAW_BUFFERS_ARB, &max_draw_buffers_);
     if (max_draw_buffers_ < 1)
       max_draw_buffers_ = 1;
   }
+  if (feature_info_->feature_flags().ext_blend_func_extended) {
+    GetIntegerv(GL_MAX_DUAL_SOURCE_DRAW_BUFFERS,
+                &max_dual_source_draw_buffers_);
+    if (max_dual_source_draw_buffers_ < 1)
+      max_dual_source_draw_buffers_ = 0;

[Mark Kilgard, 2015/08/28 19:53:24]

Context: just to set expectations, the value of GL_MAX_DUAL_SOURCE_DRAW_BUFFERS
is 1 for all GPUs which I am aware (NVIDIA or otherwise).

In other words, this functionality isn't really orthogonal to multiple render
targets.

This kind of makes sense because source two colors for the blend function is a
different way of using multiple shader color outputs that writing to multiple
color buffers.

+  }
 
   buffer_manager_.reset(
       new BufferManager(memory_tracker_.get(), feature_info_.get()));
   framebuffer_manager_.reset(
       new FramebufferManager(max_draw_buffers_, max_color_attachments_,
                              context_type, framebuffer_completeness_cache_));
   renderbuffer_manager_.reset(new RenderbufferManager(
       memory_tracker_.get(), max_renderbuffer_size, max_samples,
       feature_info_.get()));
   shader_manager_.reset(new ShaderManager());
@@ skipping 126 matching lines @@
   }
   if (feature_info_->workarounds().max_vertex_uniform_vectors) {
     max_vertex_uniform_vectors_ =
         std::min(max_vertex_uniform_vectors_,
                  static_cast<uint32>(
                      feature_info_->workarounds().max_vertex_uniform_vectors));
   }
 
   path_manager_.reset(new PathManager());
 
-  program_manager_.reset(new ProgramManager(
-      program_cache_, max_varying_vectors_, feature_info_.get()));
+  program_manager_.reset(
+      new ProgramManager(program_cache_, max_varying_vectors_,
+                         max_dual_source_draw_buffers_, feature_info_.get()));
 
   if (!texture_manager_->Initialize()) {
     LOG(ERROR) << "Context::Group::Initialize failed because texture manager "
                << "failed to initialize.";
     return false;
   }
 
   decoders_.push_back(base::AsWeakPtr<GLES2Decoder>(decoder));
   return true;
 }
@@ skipping 141 matching lines @@
     GLuint client_id, GLuint* service_id) const {
   Buffer* buffer = buffer_manager_->GetBuffer(client_id);
   if (!buffer)
     return false;
   *service_id = buffer->service_id();
   return true;
 }
 
 }  // namespace gles2
 }  // namespace gpu