disable vertex attributes at resetContext time

[bsalomon, 2011-10-19 13:15:35]

http://codereview.appspot.com/5309043/diff/2001/src/gpu/GrGLProgram.h
File src/gpu/GrGLProgram.h (left):

http://codereview.appspot.com/5309043/diff/2001/src/gpu/GrGLProgram.h#oldcode75
src/gpu/GrGLProgram.h:75: return 2 + GrDrawTarget::kMaxTexCoords;
These weren't updated when earlier attributes were inserted. However, they
aren't currently being used so it didn't cause any problems in practice.

http://codereview.appspot.com/5309043/diff/2001/src/gpu/GrGpuGLShaders.cpp
File src/gpu/GrGpuGLShaders.cpp (right):

http://codereview.appspot.com/5309043/diff/2001/src/gpu/GrGpuGLShaders.cpp#ne...
src/gpu/GrGpuGLShaders.cpp:371: 
We now disable all vertex attributes (except pos) rather than just the ones we
happen to use. This prevents another problem from popping up if third party code
left an attribute enabled that we don't use.

[reed1, 2011-10-19 13:20:38]

LGTM w/ suggestions

http://codereview.appspot.com/5309043/diff/2001/src/gpu/GrGpuGLShaders.cpp
File src/gpu/GrGpuGLShaders.cpp (right):

http://codereview.appspot.com/5309043/diff/2001/src/gpu/GrGpuGLShaders.cpp#ne...
src/gpu/GrGpuGLShaders.cpp:371: 
Should your explanation be incorporated into a comment?

On 2011/10/19 13:15:35, bsalomon wrote:
> We now disable all vertex attributes (except pos) rather than just the ones we
> happen to use. This prevents another problem from popping up if third party
code
> left an attribute enabled that we don't use.

[bsalomon, 2011-10-19 13:26:40]

Closed with r2494, this comment added:

// Third party GL code may have left vertex attributes enabled. Some GL
// implementations (osmesa) may read vetex attributes that are not required
// by the current shader. Therefore, we have to ensure that only the
// attributes we require for the current draw are enabled or we may cause an
// invalid read.