Blacklist MSAA for GPU Raster on Intel GPUs

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 <vector>
 
 #include "base/command_line.h"
@@ skipping 213 matching lines @@
       command_line->HasSwitch(switches::kDisableVirtualContexts);
 
   // The shader translator is needed to translate from WebGL-conformant GLES SL
   // to normal GLES SL, enforce WebGL conformance, translate from GLES SL 1.0 to
   // target context GLSL, etc.
   // The flag here is for testing only.
   disable_shader_translator_ =
       command_line->HasSwitch(switches::kDisableGLSLTranslator);
 
   unsafe_es3_apis_enabled_ = false;
+
+  // Default context_type_ to a GLES2 Context.
+  context_type_ = CONTEXT_TYPE_OPENGLES2;
 }
 
-bool FeatureInfo::Initialize() {
-  disallowed_features_ = DisallowedFeatures();
+bool FeatureInfo::Initialize(ContextType context_type,
+                             const DisallowedFeatures& disallowed_features) {
+  disallowed_features_ = disallowed_features;
+  context_type_ = context_type;
   InitializeFeatures();
   return true;
 }
 
-bool FeatureInfo::Initialize(const DisallowedFeatures& disallowed_features) {
-  disallowed_features_ = disallowed_features;
-  InitializeFeatures();
-  return true;
+bool FeatureInfo::InitializeForTesting() {
+  return Initialize(CONTEXT_TYPE_OPENGLES2, DisallowedFeatures());
 }
 
 bool IsGL_REDSupportedOnFBOs() {
   // Skia uses GL_RED with frame buffers, unfortunately, Mesa claims to support
   // GL_EXT_texture_rg, but it doesn't support it on frame buffers.  To fix
   // this, we try it, and if it fails, we don't expose GL_EXT_texture_rg.
   GLint fb_binding = 0;
   GLint tex_binding = 0;
   glGetIntegerv(GL_FRAMEBUFFER_BINDING, &fb_binding);
   glGetIntegerv(GL_TEXTURE_BINDING_2D, &tex_binding);
@@ skipping 859 matching lines @@
   if (workarounds_.avoid_egl_image_target_texture_reuse) {
     TextureDefinition::AvoidEGLTargetTextureReuse();
   }
 
   if (gl_version_info_->IsLowerThanGL(4, 3)) {
     // crbug.com/481184.
     // GL_PRIMITIVE_RESTART_FIXED_INDEX is only available on Desktop GL 4.3+,
     // but we emulate ES 3.0 on top of Desktop GL 4.2+.
     feature_flags_.emulate_primitive_restart_fixed_index = true;
   }
+
+  if (workarounds_.disable_msaa_on_non_webgl_contexts) {

[Zhenyao Mo, 2015/09/30 23:50:12]

This is inconsistent with the rest of the code.  Basically you should check this
workaround where you set these flags earlier in this function, not resetting
them in the end.

[ericrk, 2015/10/01 17:13:11]

yup, good point - restructured this.

+    // crbug.com/527565 - On some GPUs, MSAA does not perform acceptably for
+    // rasterization. We disable it on non-WebGL contexts. For WebGL contexts
+    // we leave it up to the site to decide whether to enable MSAA.
+    switch (context_type_) {
+      case CONTEXT_TYPE_WEBGL1:
+      case CONTEXT_TYPE_WEBGL2:
+        // WebGL contexts, ignore this flag.
+        break;
+      case CONTEXT_TYPE_OPENGLES2:
+      case CONTEXT_TYPE_OPENGLES3:
+        // Non-WebGL context, disable multisampling.
+        feature_flags_.chromium_framebuffer_multisample = false;
+        feature_flags_.multisampled_render_to_texture = false;
+    }
+  }
 }
 
 bool FeatureInfo::IsES3Capable() const {
   if (!enable_unsafe_es3_apis_switch_)
     return false;
   if (gl_version_info_)
     return gl_version_info_->IsES3Capable();
   return false;
 }
 
@@ skipping 70 matching lines @@
   if (pos == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu