Implement support for rendering to 32-bit float textures on ES3

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index f913c4883d5ebdb892dd908c2d97842b026ba4fc..9a7da5db2382211d3af9fb91d2128a44eb678172 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -80,6 +80,8 @@ namespace {
 static const char kOESDerivativeExtension[] = "GL_OES_standard_derivatives";
 static const char kEXTFragDepthExtension[] = "GL_EXT_frag_depth";
 static const char kEXTDrawBuffersExtension[] = "GL_EXT_draw_buffers";
+static const char kCHROMIUMColorBufferFloatExtension[] =
+    "GL_CHROMIUM_color_buffer_float";
 
 #if !defined(ANGLE_SH_VERSION) || ANGLE_SH_VERSION < 108
 khronos_uint64_t CityHashForAngle(const char* name, unsigned int len) {
@@ -1668,6 +1670,7 @@ class GLES2DecoderImpl : public GLES2Decoder,
   bool derivatives_explicitly_enabled_;
   bool frag_depth_explicitly_enabled_;
   bool draw_buffers_explicitly_enabled_;
+  bool chromium_color_buffer_float_explicitly_enabled_;

[piman, 2014/02/07 00:43:10]

I don't think we need this. Since we decided that WebGL assumes the extension is
there (but allows it to fail), and the other clients would test for the
extension and only use it if it's there, we shouldn't need to explicitly
EnableFeatureCHROMIUM to use it.

EnableFeatureCHROMIUM is there essentially to change the validation, and really
only for glsl. This doesn't have any glsl impact, so we don't need to do this
dance.

[oetuaho-nv, 2014/02/07 09:26:58]

Okay. I just got the idea from earlier reviews that this should not be enabled
by default, but making it so will make things easier.

 
   bool compile_shader_always_succeeds_;
 
@@ -2167,6 +2170,7 @@ GLES2DecoderImpl::GLES2DecoderImpl(ContextGroup* group)
       derivatives_explicitly_enabled_(false),
       frag_depth_explicitly_enabled_(false),
       draw_buffers_explicitly_enabled_(false),
+      chromium_color_buffer_float_explicitly_enabled_(false),
       compile_shader_always_succeeds_(false),
       service_logging_(CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableGPUServiceLoggingGPU)),
@@ -2959,7 +2963,8 @@ bool GLES2DecoderImpl::CheckFramebufferValid(
     return true;
   }
 
-  GLenum completeness = framebuffer->IsPossiblyComplete();
+  GLenum completeness = framebuffer->IsPossiblyComplete(
+      chromium_color_buffer_float_explicitly_enabled_);
   if (completeness != GL_FRAMEBUFFER_COMPLETE) {
     LOCAL_SET_GL_ERROR(
         GL_INVALID_FRAMEBUFFER_OPERATION, func_name, "framebuffer incomplete");
@@ -4895,7 +4900,8 @@ GLenum GLES2DecoderImpl::DoCheckFramebufferStatus(GLenum target) {
   if (!framebuffer) {
     return GL_FRAMEBUFFER_COMPLETE;
   }
-  GLenum completeness = framebuffer->IsPossiblyComplete();
+  GLenum completeness = framebuffer->IsPossiblyComplete(
+      chromium_color_buffer_float_explicitly_enabled_);
   if (completeness != GL_FRAMEBUFFER_COMPLETE) {
     return completeness;
   }
@@ -7600,6 +7606,17 @@ error::Error GLES2DecoderImpl::HandleGetString(
         } else {
           extensions = feature_info_->extensions().c_str();
         }
+        // Strip out CHROMIUM_color_buffer_float for all contexts that have
+        // not enabled it to emulate GLES2 more closely.
+        if (!chromium_color_buffer_float_explicitly_enabled_) {
+          size_t offset = extensions.find(
+              kCHROMIUMColorBufferFloatExtension);
+          if (std::string::npos != offset) {
+            extensions.replace(offset,
+                               arraysize(kCHROMIUMColorBufferFloatExtension),
+                               std::string());
+          }
+        }
         std::string surface_extensions = surface_->GetExtensions();
         if (!surface_extensions.empty())
           extensions += " " + surface_extensions;
@@ -9066,6 +9083,14 @@ error::Error GLES2DecoderImpl::HandleRequestExtensionCHROMIUM(
     return error::kInvalidArguments;
   }
 
+  bool desire_chromium_color_buffer_float =
+      feature_str.find("GL_CHROMIUM_color_buffer_float") != std::string::npos;
+
+  if (desire_chromium_color_buffer_float &&
+      feature_info_->feature_flags().chromium_color_buffer_float) {
+    chromium_color_buffer_float_explicitly_enabled_ = true;
+  }
+
   bool desire_webgl_glsl_validation =
       feature_str.find("GL_CHROMIUM_webglsl") != std::string::npos;
   bool desire_standard_derivatives = false;