Add GL implementation to GrSingleTextureEffect, call from GrContext

[TomH, 2012-07-17 19:16:24]

There are a couple of lines in GrContext with FIXME comments (1864, 1929). If I
uncomment them and comment out the paired GrPaint::setTexture() calls,

1. "out/Debug/gm --match circles" succeeds
2. "out/Debug/gm" fails the assert in GrContext.h line 881
    1 == temp->getRefCnt()

[TomH, 2012-07-19 16:01:54]

PTAL?
I'm a little unhappy at the verbosity increase, but I think that'll get better
over time (as we move Matrix, Filter, Swizzle onto this class, we'll get extra
parameters to the constructor rather than extra lines - although then needing to
get *rid* of this class and move it to a helper to support multi-texture
varying-texture effects will reopen the can of worms).

[bsalomon, 2012-07-19 17:32:11]

On 2012/07/19 16:01:54, TomH wrote:
> PTAL?
> I'm a little unhappy at the verbosity increase, but I think that'll get better
> over time (as we move Matrix, Filter, Swizzle onto this class, we'll get extra
> parameters to the constructor rather than extra lines - although then needing
to
> get *rid* of this class and move it to a helper to support multi-texture
> varying-texture effects will reopen the can of worms).

LGTM

Is it common enough that we should have a special setter on SamplerState (moved
to DrawState when SamplerState goes away)?

Something like:
void GrSamplerState::setBasicTextureStage(texture, matrix);

[TomH, 2012-07-19 17:32:54]

On 2012/07/19 17:32:11, bsalomon wrote:
> On 2012/07/19 16:01:54, TomH wrote:
> > PTAL?
> > I'm a little unhappy at the verbosity increase, but I think that'll get
better
> > over time (as we move Matrix, Filter, Swizzle onto this class, we'll get
extra
> > parameters to the constructor rather than extra lines - although then
needing
> to
> > get *rid* of this class and move it to a helper to support multi-texture
> > varying-texture effects will reopen the can of worms).
> 
> LGTM
> 
> Is it common enough that we should have a special setter on SamplerState
(moved
> to DrawState when SamplerState goes away)?
> 
> Something like:
> void GrSamplerState::setBasicTextureStage(texture, matrix);

Ooh, I like, although I'd name it create? Will file strawman CL once I've landed
this one.

[TomH, 2012-07-19 17:59:07]

Turns out there was a bug on 3+? codepaths not being caught by gm and only
caught by one unit test (WritePixels):

A common idiom previously was
  paint->setTexture(...)
  paint->sampler->reset(...)

That got turned into
  paint->sampler->setCustomStage(...)
  paint->sampler->reset(...)
which failed. Reordering the lines fixes the test failures.

[TomH, 2012-07-19 18:01:24]

Closing with r4677