Add initial support for NV_path_rendering extension to gpu command buffer

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 5e26477a6d6b2a6823ef80c3ef78545a47c47b18..f54b8ff149bc3bcffa970d07a8a7f796e37302d9 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -987,6 +987,9 @@ class GLES2DecoderImpl : public GLES2Decoder,
 
   void DoLoseContextCHROMIUM(GLenum current, GLenum other);
 
+  void DoMatrixLoadfCHROMIUM(GLenum matrix_mode, const GLfloat* matrix);
+  void DoMatrixLoadIdentityCHROMIUM(GLenum matrix_mode);
+
   // Creates a Program for the given program.
   Program* CreateProgram(
       GLuint client_id, GLuint service_id) {
@@ -10648,6 +10651,45 @@ void GLES2DecoderImpl::DoLoseContextCHROMIUM(GLenum current, GLenum other) {
   current_decoder_error_ = error::kLostContext;
 }
 
+void GLES2DecoderImpl::DoMatrixLoadfCHROMIUM(GLenum matrix_mode,
+                                             const GLfloat* matrix) {
+  DCHECK(matrix_mode == GL_PATH_PROJECTION_CHROMIUM ||
+         matrix_mode == GL_PATH_MODELVIEW_CHROMIUM);
+  if (!features().chromium_path_rendering) {
+    LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
+                       "glMatrixLoadfCHROMIUM",
+                       "function not available");
+    return;
+  }
+
+  GLfloat* target_matrix = matrix_mode == GL_PATH_PROJECTION_CHROMIUM
+                               ? state_.projection_matrix
+                               : state_.modelview_matrix;
+  memcpy(target_matrix, matrix, sizeof(GLfloat) * 16);
+  glMatrixLoadfEXT(matrix_mode, matrix);

[vmiura, 2014/08/25 19:42:22]

We're using GL_PATH_MODELVIEW_CHROMIUM/GL_PATH_PROJECTION_CHROMIUM directly with
glMatrixLoadfEXT.

Could you comment here, and in gl2chromium.h/gl_bindings.h that:
  GL_PATH_MODELVIEW_CHROMIUM == GL_MODELVIEW
  GL_PATH_PROJECTION_CHROMIUM == GL_PROJECTION

[Kimmo Kinnunen, 2014/08/26 06:48:33]

Done.

I added comments here and in gl_bindings.h and in the commit message. I left
gl2chromium.h out because it didn't seem to fit there, hope it's ok.

The thing to note is that conceptually the trick you noticed is done in the
extension spec, not in the patch. In the patch, GL_PATH_MODELVIEW_CHROMIUM
actually corresponds to GL_PATH_MODELVIEW_NV, similarly to
glSomePathFuncCHROMIUM corresponds to glSomePathFuncNV. 

The gl headers in chromium do not yet have the GL_PATH_MODELVIEW_NV, so it can
not, unfortunately, be documented by compile-time assertions.

+}
+
+void GLES2DecoderImpl::DoMatrixLoadIdentityCHROMIUM(GLenum matrix_mode) {
+  DCHECK(matrix_mode == GL_PATH_PROJECTION_CHROMIUM ||
+         matrix_mode == GL_PATH_MODELVIEW_CHROMIUM);
+  if (!features().chromium_path_rendering) {
+    LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
+                       "glMatrixLoadIdentityCHROMIUM",
+                       "function not available");
+    return;
+  }
+
+  static GLfloat kIdentityMatrix[16] = {1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f,
+                                        0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f,
+                                        0.0f, 0.0f, 0.0f, 1.0f};
+
+  GLfloat* target_matrix = matrix_mode == GL_PATH_PROJECTION_CHROMIUM
+                               ? state_.projection_matrix
+                               : state_.modelview_matrix;
+  memcpy(target_matrix, kIdentityMatrix, sizeof(kIdentityMatrix));
+  glMatrixLoadIdentityEXT(matrix_mode);
+}
+
 bool GLES2DecoderImpl::ValidateAsyncTransfer(
     const char* function_name,
     TextureRef* texture_ref,