Implement EXT_draw_buffers WebGL extention support in command buffer.

gpu/command_buffer/service/feature_info.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/feature_info.h"
 
 #include <set>
 
 #include "base/command_line.h"
 #include "base/string_number_conversions.h"
@@ skipping 63 matching lines @@
       chromium_stream_texture(false),
       angle_translated_shader_source(false),
       angle_pack_reverse_row_order(false),
       arb_texture_rectangle(false),
       angle_instanced_arrays(false),
       occlusion_query_boolean(false),
       use_arb_occlusion_query2_for_occlusion_query_boolean(false),
       use_arb_occlusion_query_for_occlusion_query_boolean(false),
       native_vertex_array_object(false),
       disable_workarounds(false),
-      enable_shader_name_hashing(false) {
+      enable_shader_name_hashing(false),
+      ext_draw_buffers(false) {
 }
 
 FeatureInfo::Workarounds::Workarounds()
     : clear_alpha_in_readpixels(false),
       needs_glsl_built_in_function_emulation(false),
       needs_offscreen_buffer_workaround(false),
       reverse_point_sprite_coord_origin(false),
       set_texture_filter_before_generating_mipmap(false),
       use_current_program_after_successful_link(false),
       restore_scissor_on_fbo_change(false),
@@ skipping 511 matching lines @@
   }
 
   if (extensions.Contains("GL_ANGLE_instanced_arrays") ||
       (extensions.Contains("GL_ARB_instanced_arrays") &&
        extensions.Contains("GL_ARB_draw_instanced"))) {
     AddExtensionString("GL_ANGLE_instanced_arrays");
     feature_flags_.angle_instanced_arrays = true;
     validators_.vertex_attribute.AddValue(GL_VERTEX_ATTRIB_ARRAY_DIVISOR_ANGLE);
   }
 
+  if (extensions.Contains("GL_ARB_draw_buffers")) {

[greggman, 2013/03/08 21:48:28]

Don't you also want 
  || extensions.Contains("GL_EXT_draw_buffers") 

as I think that's what ANGLE will return?

[Zhenyao Mo, 2013/03/13 01:22:02]

I want to do it separately and explicitly when ANGLE EXT_draw_buffer is
implemented and tested.

+    AddExtensionString("GL_EXT_draw_buffers");
+    feature_flags_.ext_draw_buffers = true;
+
+    GLint max_color_attachments = 0;
+    glGetIntegerv(GL_MAX_COLOR_ATTACHMENTS_EXT, &max_color_attachments);
+    for (GLenum i = GL_COLOR_ATTACHMENT1_EXT;
+         i < static_cast<GLenum>(GL_COLOR_ATTACHMENT0 + max_color_attachments);
+         ++i) {
+      validators_.attachment.AddValue(i);
+    }
+
+    validators_.g_l_state.AddValue(GL_MAX_COLOR_ATTACHMENTS_EXT);
+    validators_.g_l_state.AddValue(GL_MAX_DRAW_BUFFERS_ARB);
+    GLint max_draw_buffers = 0;
+    glGetIntegerv(GL_MAX_DRAW_BUFFERS_ARB, &max_draw_buffers);
+    for (GLenum i = GL_DRAW_BUFFER0_ARB;
+         i < static_cast<GLenum>(GL_DRAW_BUFFER0_ARB + max_draw_buffers);
+         ++i) {
+      validators_.g_l_state.AddValue(i);
+    }
+  }
+
   if (!disallowed_features_.swap_buffer_complete_callback)
     AddExtensionString("GL_CHROMIUM_swapbuffers_complete_callback");
 
   if (!feature_flags_.disable_workarounds) {
     workarounds_.set_texture_filter_before_generating_mipmap = true;
     workarounds_.clear_alpha_in_readpixels = true;
 
     if (is_nvidia) {
       workarounds_.use_current_program_after_successful_link = true;
     }
@@ skipping 43 matching lines @@
   if (extensions_.find(str) == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu