Add support for reading the dst pixel value in an effect. Use in a new effect for the kDarken xfer mode.
The current implementation is to always make a copy of the entire dst before the draw.
It will only succeed if the RT is also a texture.
Obviously, there is lots of room for improvement.
Review URL: https://codereview.chromium.org/13314002
git-svn-id: http://skia.googlecode.com/svn/trunk@8449 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGLProgramDesc.cpp b/src/gpu/gl/GrGLProgramDesc.cpp
index 98280e2..6ed5473 100644
--- a/src/gpu/gl/GrGLProgramDesc.cpp
+++ b/src/gpu/gl/GrGLProgramDesc.cpp
@@ -9,6 +9,7 @@
#include "GrBackendEffectFactory.h"
#include "GrDrawEffect.h"
#include "GrEffect.h"
+#include "GrGLShaderBuilder.h"
#include "GrGpuGL.h"
void GrGLProgramDesc::Build(const GrDrawState& drawState,
@@ -17,6 +18,7 @@
GrBlendCoeff srcCoeff,
GrBlendCoeff dstCoeff,
const GrGpuGL* gpu,
+ const GrDeviceCoordTexture* dstCopy,
GrGLProgramDesc* desc) {
// This should already have been caught
@@ -80,6 +82,7 @@
desc->fCoverageInput = kAttribute_ColorInput;
}
+ bool readsDst = false;
int lastEnabledStage = -1;
for (int s = 0; s < GrDrawState::kNumStages; ++s) {
@@ -93,11 +96,22 @@
GrDrawState::kLocalCoords_AttribBindingsBit);
GrDrawEffect drawEffect(drawState.getStage(s), explicitLocalCoords);
desc->fEffectKeys[s] = factory.glEffectKey(drawEffect, gpu->glCaps());
+ if (effect->willReadDst()) {
+ readsDst = true;
+ }
} else {
desc->fEffectKeys[s] = 0;
}
}
+ if (readsDst) {
+ GrAssert(NULL != dstCopy);
+ desc->fDstRead = GrGLShaderBuilder::KeyForDstRead(dstCopy->texture(), gpu->glCaps());
+ GrAssert(0 != desc->fDstRead);
+ } else {
+ desc->fDstRead = 0;
+ }
+
desc->fDualSrcOutput = kNone_DualSrcOutput;
// Currently the experimental GS will only work with triangle prims (and it doesn't do anything