Introduction of set of functions to manage generation of texture fetch shader code.
A new set of routines have been added to GrGLShaderBuilder to emit texture fetches, taking into consideration the format of the texture to be accessed, and the channel swizzle.
Review URL: https://codereview.appspot.com/6446072
git-svn-id: http://skia.googlecode.com/svn/trunk@4919 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGLShaderBuilder.cpp b/src/gpu/gl/GrGLShaderBuilder.cpp
index 2844953..0d2a1ec 100644
--- a/src/gpu/gl/GrGLShaderBuilder.cpp
+++ b/src/gpu/gl/GrGLShaderBuilder.cpp
@@ -8,6 +8,7 @@
#include "gl/GrGLShaderBuilder.h"
#include "gl/GrGLProgram.h"
#include "gl/GrGLUniformHandle.h"
+#include "GrTexture.h"
// number of each input/output type in a single allocation block
static const int kVarsPerBlock = 8;
@@ -21,6 +22,50 @@
typedef GrGLUniformManager::UniformHandle UniformHandle;
///////////////////////////////////////////////////////////////////////////////
+static SkString build_sampler_string(GrGLShaderBuilder::SamplerMode samplerMode) {
+ SkString sampler("texture2D");
+ switch (samplerMode) {
+ case GrGLShaderBuilder::kDefault_SamplerMode:
+ break;
+ case GrGLShaderBuilder::kProj_SamplerMode:
+ sampler.append("Proj");
+ break;
+ case GrGLShaderBuilder::kExplicitDivide_SamplerMode:
+ GrAssert(false); // Not Implemented
+ break;
+ }
+
+ return sampler;
+}
+
+static bool texture_requires_alpha_to_red_swizzle(const GrGLCaps& caps,
+ const GrTextureAccess& access) {
+ return GrPixelConfigIsAlphaOnly(access.getTexture()->config()) && caps.textureRedSupport() &&
+ access.referencesAlpha();
+}
+
+static SkString build_swizzle_string(const GrTextureAccess& textureAccess,
+ const GrGLCaps& caps) {
+ const GrTextureAccess::Swizzle& swizzle = textureAccess.getSwizzle();
+ if (0 == swizzle[0]) {
+ return SkString("");
+ }
+
+ SkString swizzleOut(".");
+ bool alphaIsRed = texture_requires_alpha_to_red_swizzle(caps, textureAccess);
+ for (int offset = 0; offset < 4 && swizzle[offset]; ++offset) {
+ if (alphaIsRed && 'a' == swizzle[offset]) {
+ swizzleOut.appendf("r");
+ } else {
+ swizzleOut.appendf("%c", swizzle[offset]);
+ }
+ }
+
+ return swizzleOut;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
// Architectural assumption: always 2-d input coords.
// Likely to become non-constant and non-static, perhaps even
// varying by stage, if we use 1D textures for gradients!
@@ -120,6 +165,34 @@
fFSCode.appendf("%s%s;\n", fSwizzle.c_str(), fModulate.c_str());
}
+void GrGLShaderBuilder::emitCustomTextureLookup(SamplerMode samplerMode,
+ const GrTextureAccess& textureAccess,
+ const char* samplerName,
+ const char* coordName) {
+ GrAssert(samplerName && coordName);
+ SkString sampler = build_sampler_string(samplerMode);
+ SkString swizzle = build_swizzle_string(textureAccess, fContext.caps());
+
+ fFSCode.appendf("%s( %s, %s)%s;\n", sampler.c_str(), samplerName,
+ coordName, swizzle.c_str());
+}
+
+GrCustomStage::StageKey GrGLShaderBuilder::KeyForTextureAccess(const GrTextureAccess& access,
+ const GrGLCaps& caps) {
+ GrCustomStage::StageKey key = 0;
+ // Assume that swizzle support implies that we never have to modify a shader to adjust
+ // for texture format/swizzle settings.
+ if (caps.textureSwizzleSupport()) {
+ return key;
+ }
+
+ if (texture_requires_alpha_to_red_swizzle(caps, access)) {
+ key = 1;
+ }
+
+ return key;
+}
+
GrGLUniformManager::UniformHandle GrGLShaderBuilder::addUniformArray(uint32_t visibility,
GrSLType type,
const char* name,