Implement support for KHR_blend_equation_advanced

src/gpu/gl/builders/GrGLFragmentShaderBuilder.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGLFragmentShaderBuilder.h"
 #include "GrGLProgramBuilder.h"
 #include "../GrGLGpu.h"
@@ skipping 18 matching lines @@
                 break;
             case kLow_GrSLPrecision:
                 str->append("precision lowp float;\n");
                 break;
             default:
                 SkFAIL("Unknown precision value.");
         }
     }
 }
 
+static const char* specific_layout_qualifier_name(GrBlendEquation equation) {
+    SkASSERT(GrBlendEquationIsAdvanced(equation));
+
+    static const char* kLayoutQualifierNames[] = {
+        "blend_support_screen",
+        "blend_support_overlay",
+        "blend_support_darken",
+        "blend_support_lighten",
+        "blend_support_colordodge",
+        "blend_support_colorburn",
+        "blend_support_hardlight",
+        "blend_support_softlight",
+        "blend_support_difference",
+        "blend_support_exclusion",
+        "blend_support_multiply",
+        "blend_support_hsl_hue",
+        "blend_support_hsl_saturation",
+        "blend_support_hsl_color",
+        "blend_support_hsl_luminosity"
+    };
+    return kLayoutQualifierNames[equation - kFirstAdvancedGrBlendEquation];
+
+    GR_STATIC_ASSERT(0 == kScreen_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(1 == kOverlay_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(2 == kDarken_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(3 == kLighten_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(4 == kColorDodge_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(5 == kColorBurn_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(6 == kHardLight_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(7 == kSoftLight_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(8 == kDifference_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(9 == kExclusion_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(10 == kMultiply_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(11 == kHSLHue_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(12 == kHSLSaturation_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(13 == kHSLColor_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(14 == kHSLLuminosity_GrBlendEquation - kFirstAdvancedGrBlendEquation);
+    GR_STATIC_ASSERT(SK_ARRAY_COUNT(kLayoutQualifierNames) ==
+                     kTotalGrBlendEquationCount - kFirstAdvancedGrBlendEquation);
+}
+
 GrGLFragmentShaderBuilder::DstReadKey
 GrGLFragmentShaderBuilder::KeyForDstRead(const GrTexture* dstCopy, const GrGLCaps& caps) {
     uint32_t key = kYesDstRead_DstReadKeyBit;
     if (caps.glslCaps()->fbFetchSupport()) {
         return key;
     }
     SkASSERT(dstCopy);
     if (!caps.textureSwizzleSupport() && GrPixelConfigIsAlphaOnly(dstCopy->config())) {
         // The fact that the config is alpha-only must be considered when generating code.
         key |= kUseAlphaConfig_DstReadKeyBit;
@@ skipping 127 matching lines @@
             this->enableCustomOutput();
             fOutputs[fCustomColorOutputIndex].setTypeModifier(GrShaderVar::kInOut_TypeModifier);
             fbFetchColorName = declared_color_output_name();
         }
         return fbFetchColorName;
     } else {
         return kDstCopyColorName;
     } 
 }
 
+void GrGLFragmentShaderBuilder::enableAdvancedBlendEquationIfNeeded(GrBlendEquation equation) {
+    SkASSERT(GrBlendEquationIsAdvanced(equation));
+
+    const GrGLSLCaps& caps = *fProgramBuilder->gpu()->glCaps().glslCaps();
+    if (!caps.mustEnableAdvBlendEqs()) {
+        return;
+    }
+
+    this->addFeature(1 << kBlendEquationAdvanced_GLSLPrivateFeature,
+                     "GL_KHR_blend_equation_advanced");
+    if (caps.mustEnableSpecificAdvBlendEqs()) {
+        this->addLayoutQualifier(specific_layout_qualifier_name(equation), kOut_InterfaceQualifier);
+    } else {
+        this->addLayoutQualifier("blend_support_all_equations", kOut_InterfaceQualifier);
+    }
+}
+
 void GrGLFragmentShaderBuilder::enableCustomOutput() {
     if (!fHasCustomColorOutput) {
         fHasCustomColorOutput = true;
         fCustomColorOutputIndex = fOutputs.count();
         fOutputs.push_back().set(kVec4f_GrSLType,
                                  GrGLShaderVar::kOut_TypeModifier,
                                  declared_color_output_name());
     }
 }
 
@@ skipping 40 matching lines @@
     }
 }
 
 void GrGLFragmentShaderBuilder::addVarying(GrGLVarying* v, GrSLPrecision fsPrec) {
     v->fFsIn = v->fVsOut;
     if (v->fGsOut) {
         v->fFsIn = v->fGsOut;
     }
     fInputs.push_back().set(v->fType, GrGLShaderVar::kVaryingIn_TypeModifier, v->fFsIn, fsPrec);
 }