Fix ReadPixels implementation specific read format/type on desktop GL.

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 <sstream>
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
@@ skipping 791 matching lines @@
     case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
       return 4;
     case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
       return 5;
     default:
       NOTREACHED();
       return 0;
   }
 }
 
-uint32 GLES2Util::GetPreferredGLReadPixelsFormat(uint32 internal_format) {
+uint32 GLES2Util::GetGLReadPixelsImplementationFormat(uint32 internal_format) {
   switch (internal_format) {
-    case GL_RGB16F_EXT:
-    case GL_RGB32F_EXT:
+    case GL_R8:
+    case GL_R16F:
+    case GL_R32F:
+      return GL_RED;
+    case GL_R8UI:
+    case GL_R8I:
+    case GL_R16UI:
+    case GL_R16I:
+    case GL_R32UI:
+    case GL_R32I:
+      return GL_RED_INTEGER;
+    case GL_RG8:
+    case GL_RG16F:
+    case GL_RG32F:
+      return GL_RG;
+    case GL_RG8UI:
+    case GL_RG8I:
+    case GL_RG16UI:
+    case GL_RG16I:
+    case GL_RG32UI:
+    case GL_RG32I:
+      return GL_RG_INTEGER;
+    case GL_RGB:
+    case GL_RGB8:
+    case GL_RGB565:
+    case GL_RGB16F:
+    case GL_RGB32F:
+    case GL_R11F_G11F_B10F:
       return GL_RGB;
-    case GL_RGBA16F_EXT:
-    case GL_RGBA32F_EXT:
-      return GL_RGBA;
+    case GL_RGBA8UI:
+    case GL_RGBA8I:
+    case GL_RGB10_A2UI:
+    case GL_RGBA16UI:
+    case GL_RGBA16I:
+    case GL_RGBA32UI:
+    case GL_RGBA32I:
+      return GL_RGBA_INTEGER;
     default:
       return GL_RGBA;
   }
 }
 
-uint32 GLES2Util::GetPreferredGLReadPixelsType(
+uint32 GLES2Util::GetGLReadPixelsImplementationType(
     uint32 internal_format, uint32 texture_type) {
   switch (internal_format) {
-    case GL_RGBA32F_EXT:
-    case GL_RGB32F_EXT:
+    case GL_R16UI:
+    case GL_RG16UI:
+    case GL_RGBA16UI:
+    case GL_RGB10_A2:
+    case GL_RGB10_A2UI:
+      return GL_UNSIGNED_SHORT;
+    case GL_R32UI:
+    case GL_RG32UI:
+    case GL_RGBA32UI:
+      return GL_UNSIGNED_INT;
+    case GL_R8I:
+    case GL_RG8I:
+    case GL_RGBA8I:
+      return GL_BYTE;
+    case GL_R16I:
+    case GL_RG16I:
+    case GL_RGBA16I:
+      return GL_SHORT;
+    case GL_R32I:
+    case GL_RG32I:
+    case GL_RGBA32I:
+      return GL_INT;
+    case GL_R32F:
+    case GL_RG32F:
+    case GL_RGB32F:
+    case GL_RGBA32F:
       return GL_FLOAT;
-    case GL_RGBA16F_EXT:
-    case GL_RGB16F_EXT:
-      return GL_HALF_FLOAT_OES;
+    case GL_R16F:
+    case GL_RG16F:
+    case GL_RGB16F:
+    case GL_RGBA16F:
+      // TODO(zmo): Consider return GL_HALF_FLOAT on ES3.
+      return GL_FLOAT;

[Ken Russell (switch to Gerrit), 2015/08/26 23:58:36]

This change may break existing WebGL 1.0 code which is using
OES_texture_half_float and expecting to be able to do ReadPixels operations with
format RGBA, type GL_HALF_FLOAT_OES. Let's please leave this code path
unchanged, and have different behavior for WebGL 1.0 and 2.0 when we implement
EXT_color_buffer_float for ES 3.0.

[Ken Russell (switch to Gerrit), 2015/08/27 00:01:10]

Another note: it looks like I was lazy and didn't check the implementation color
read format and type readback path in
sdk/tests/conformance/extensions/oes-texture-half-float.html in the WebGL
conformance tests. oes-texture-float.html in the same directory does test
RGBA/FLOAT readbacks. But since it's not guaranteed that these texture types are
renderable, the conformance tests can't easily catch regressions in this area.

+    case GL_R11F_G11F_B10F:
+      // TODO(zmo): Consider return GL_UNSIGNED_INT_10F_11F_11F_REV.
+      return GL_FLOAT;
     case GL_RGBA:
     case GL_RGB:
       // Unsized internal format, check the type
       switch (texture_type) {
         case GL_FLOAT:
         case GL_HALF_FLOAT_OES:
           return GL_FLOAT;
+        // TODO(zmo): Consider return GL_UNSIGNED_SHORT_5_6_5,
+        // GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_5_5_5_1, and
+        // GL_UNSIGNED_INT_2_10_10_10_REV.
         default:
           return GL_UNSIGNED_BYTE;
       }
     default:
       return GL_UNSIGNED_BYTE;
   }
 }
 
 uint32 GLES2Util::GetChannelsForFormat(int format) {
   switch (format) {
@@ skipping 433 matching lines @@
   }
 
   return true;
 }
 
 #include "gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu