Refactor how precision is handled with GrGLShaderVar

[bsalomon, 2012-07-11 21:17:32]

I want to be able to keep one copy of each uniform (even if it is visible in
multiple shaders).

This will cause "mediump" to be emitted in the fragment shader on unis that are
also in the frag. It's redundant since we set the default precision to mediump.
But that seems acceptable to me.

[TomH, 2012-07-12 14:42:01]

Sorry I missed this last night. Nearly LGTM.

http://codereview.appspot.com/6392049/diff/1/src/gpu/gl/GrGLShaderBuilder.cpp
File src/gpu/gl/GrGLShaderBuilder.cpp (right):

http://codereview.appspot.com/6392049/diff/1/src/gpu/gl/GrGLShaderBuilder.cpp...
src/gpu/gl/GrGLShaderBuilder.cpp:203: inline void
append_default_precision_qualifier(GrGLShaderVar::Precision p,
I think "default" doesn't belong in this name?

http://codereview.appspot.com/6392049/diff/1/src/gpu/gl/GrGLShaderBuilder.cpp...
src/gpu/gl/GrGLShaderBuilder.cpp:206: // Desktop GLSL has added precision
qualifiers but they don't do anything.
Is that a good enough reason not to emit them?

[bsalomon, 2012-07-12 14:53:37]

http://codereview.appspot.com/6392049/diff/1/src/gpu/gl/GrGLShaderBuilder.cpp
File src/gpu/gl/GrGLShaderBuilder.cpp (right):

http://codereview.appspot.com/6392049/diff/1/src/gpu/gl/GrGLShaderBuilder.cpp...
src/gpu/gl/GrGLShaderBuilder.cpp:203: inline void
append_default_precision_qualifier(GrGLShaderVar::Precision p,
On 2012/07/12 14:42:01, TomH wrote:
> I think "default" doesn't belong in this name?

I got the name from the GLSL spec:

The precision statement
     precision precision-qualifier type;
can be used to establish a default precision qualifier

http://codereview.appspot.com/6392049/diff/1/src/gpu/gl/GrGLShaderBuilder.cpp...
src/gpu/gl/GrGLShaderBuilder.cpp:206: // Desktop GLSL has added precision
qualifiers but they don't do anything.
On 2012/07/12 14:42:01, TomH wrote:
> Is that a good enough reason not to emit them?

I think so. Today we only emit the qualifiers in order for our shaders to
compile. If we get to the point where we've actually decided the max precision
we require for various computations then the qualifiers would have some meaning
and it might make sense to always emit them.

[TomH, 2012-07-12 15:08:05]

OK, whatever, ship it.

/me scorns the spec - although it might make sense in that context.

[bsalomon, 2012-07-16 14:44:04]

Landed as r4575