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

gpu/command_buffer/build_gles2_cmd_buffer.py

 #!/usr/bin/env python
 # 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.
 
 """code generator for GLES2 command buffers."""
 
 import itertools
 import os
 import os.path
@@ skipping 1490 matching lines @@
     ],
   },
   'ReadPixelFormat': {
     'type': 'GLenum',
     'valid': [
       'GL_ALPHA',
       'GL_RGB',
       'GL_RGBA',
     ],
     'valid_es3': [
+      'GL_RED',
+      'GL_RED_INTEGER',
+      'GL_RG',
+      'GL_RG_INTEGER',
+      'GL_RGB_INTEGER',
       'GL_RGBA_INTEGER',
-    ],
-    'deprecated_es3': [

[Ken Russell (switch to Gerrit), 2015/08/26 01:00:44]

What's the consequence of un-deprecating these?

[Zhenyao Mo, 2015/08/26 01:11:05]

It's a mistake to deprecate them in the first place.

-      'GL_ALPHA',
-      'GL_RGB',
+      'GL_LUMINANCE',
+      'GL_LUMINANCE_ALPHA',

[Ken Russell (switch to Gerrit), 2015/08/26 01:00:43]

It looks to me like GL_LUMINANCE and GL_LUMINANCE_ALPHA are defined in Table 3.3
rather than 3.2 in the spec, and that the implementation color read format and
type are defined as coming from Table 3.2. Can you verify?

[Zhenyao Mo, 2015/08/26 01:11:04]

3.2 defines the sized ones, and 3.3 defines the unsized ones.  Both should be
valid.

[Ken Russell (switch to Gerrit), 2015/08/26 01:53:32]

Not sure about that. ES 3.0.4 section 4.4.4 "Framebuffer Completeness":

"An internal format is color-renderable if it is one of the formats from table
3.13 noted as color-renderable or if it is unsized format RGBA or RGB. No other
formats, including compressed internal formats, are color-renderable."

I think this excludes LUMINANCE and LUMINANCE_ALPHA type textures as being valid
framebuffer object color attachments, so it's not possible to call ReadPixels
when a framebuffer is using that format and type.

     ],
   },
   'PixelType': {
     'type': 'GLenum',
     'valid': [
       'GL_UNSIGNED_BYTE',
       'GL_UNSIGNED_SHORT_5_6_5',
       'GL_UNSIGNED_SHORT_4_4_4_4',
       'GL_UNSIGNED_SHORT_5_5_5_1',
     ],
@@ skipping 67 matching lines @@
     ]
   },
   'ReadPixelType': {
     'type': 'GLenum',
     'valid': [
       'GL_UNSIGNED_BYTE',
       'GL_UNSIGNED_SHORT_5_6_5',
       'GL_UNSIGNED_SHORT_4_4_4_4',
       'GL_UNSIGNED_SHORT_5_5_5_1',
     ],
-    'invalid': [
+    'valid_es3': [
+      'GL_BYTE',
+      'GL_UNSIGNED_SHORT',
       'GL_SHORT',
-    ],
-    'valid_es3': [
       'GL_UNSIGNED_INT',
       'GL_INT',
+      'GL_HALF_FLOAT',
       'GL_FLOAT',
       'GL_UNSIGNED_INT_2_10_10_10_REV',
     ],
-    'deprecated_es3': [
-      'GL_UNSIGNED_SHORT_5_6_5',
-      'GL_UNSIGNED_SHORT_4_4_4_4',
-      'GL_UNSIGNED_SHORT_5_5_5_1',

[Ken Russell (switch to Gerrit), 2015/08/26 01:00:43]

Similarly, what's the consequence of un-deprecating these?

[Zhenyao Mo, 2015/08/26 01:11:04]

The same, table 3.3 (valid unsized ones) should also be included

-    ],
   },
   'RenderBufferFormat': {
     'type': 'GLenum',
     'valid': [
       'GL_RGBA4',
       'GL_RGB565',
       'GL_RGB5_A1',
       'GL_DEPTH_COMPONENT16',
       'GL_STENCIL_INDEX8',
     ],
@@ skipping 9434 matching lines @@
   Format(gen.generated_cpp_filenames)
 
   if gen.errors > 0:
     print "%d errors" % gen.errors
     return 1
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))