Add support for GL_CHROMIUM_consistent_uniform_locations

gpu/command_buffer/common/gles2_cmd_utils.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.
 
 // This file is here so other GLES2 related files can have a common set of
 // includes where appropriate.
 
 #include <stdio.h>
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
@@ skipping 740 matching lines @@
         return true;
       default:
         GPU_DLOG(ERROR) << "Invalid context creation attribute: " << attrib;
         return false;
     }
   }
 
   return true;
 }
 
+// Swizzles the locations to prevent developers from assuming they
+// can do math on uniforms. According to the OpenGL ES 2.0 spec
+// the location of "someuniform[1]" is not 'n' more than "someuniform[0]".

[apatrick_chromium, 2012/06/18 18:58:03]

nit: [1]->[n]

+static int32 Swizzle(int32 location) {
+  return (location & 0xF0000000U) |
+         ((location & 0x0AAAAAAAU) >> 1) |
+         ((location & 0x05555555U) << 1);
+}
+
+// Adds uniform_swizzle_ to prevent developers from assuming that locations are
+// always the same across GPUs and drivers.
+int32 GLES2Util::SwizzleLocation(int32 v) {
+  return v < 0 ? v : Swizzle(v);
+}
+
+int32 GLES2Util::UnswizzleLocation(int32 v) {
+  return v < 0 ? v : Swizzle(v);
+}
+
+int32 GLES2Util::MakeFakeLocation(int32 index, int32 element) {
+  return index + element * 0x10000;
+}
+
 #include "../common/gles2_cmd_utils_implementation_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu