Implement GL support for buffer textures

src/gpu/glsl/GrGLSL.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLSL_DEFINED
 #define GrGLSL_DEFINED
 
@@ skipping 38 matching lines @@
      */
     k320es_GrGLSLGeneration,
 };
 
 bool GrGLSLSupportsNamedFragmentShaderOutputs(GrGLSLGeneration);
 
 /**
  * Gets the name of the function that should be used to sample a 2D texture. Coord type is used
  * to indicate whether the texture is sampled using projective textured (kVec3f) or not (kVec2f).
  */
-inline const char* GrGLSLTexture2DFunctionName(GrSLType coordType, GrSLType samplerType,
-                                               GrGLSLGeneration glslGen) {
+inline const char* GrGLSLTextureFunctionName(GrSLType coordType, GrSLType samplerType,
+                                             GrGLSLGeneration glslGen) {
     SkASSERT(GrSLTypeIsSamplerType(samplerType));
+    if (kSamplerBuffer_GrSLType == samplerType) {
+        SkASSERT(kInt_GrSLType == coordType);
+        return "texelFetch";
+    }
     SkASSERT(kVec2f_GrSLType == coordType || kVec3f_GrSLType == coordType);
     // GL_TEXTURE_RECTANGLE_ARB is written against OpenGL 2.0/GLSL 1.10. At that time there were
     // separate texture*() functions. In OpenGL 3.0/GLSL 1.30 the different texture*() functions
     // were deprecated in favor or the unified texture() function. RECTANGLE textures became
     // standard in OpenGL 3.2/GLSL 1.50 and use texture(). It isn't completely clear what function
     // should be used for RECTANGLE textures in GLSL versions >= 1.30 && < 1.50. We're going with
     // using texture().
     if (glslGen >= k130_GrGLSLGeneration) {
         return (kVec2f_GrSLType == coordType) ? "texture" : "textureProj";
     }
@@ skipping 31 matching lines @@
         case kMat33f_GrSLType:
             return "mat3";
         case kMat44f_GrSLType:
             return "mat4";
         case kSampler2D_GrSLType:
             return "sampler2D";
         case kSamplerExternal_GrSLType:
             return "samplerExternalOES";
         case kSampler2DRect_GrSLType:
             return "sampler2DRect";
+        case kSamplerBuffer_GrSLType:
+            return "samplerBuffer";
         case kBool_GrSLType:
             return "bool";
         case kInt_GrSLType:
             return "int";
         case kUint_GrSLType:
             return "uint";
         default:
             SkFAIL("Unknown shader var type.");
             return ""; // suppress warning
     }
@@ skipping 234 matching lines @@
 
 /**
  * Does an inplace mul, *=, of vec4VarName by mulFactor.
  * A semicolon is added after the assignment.
  */
 void GrGLSLMulVarBy4f(SkString* outAppend, const char* vec4VarName, const GrGLSLExpr4& mulFactor);
 
 #include "GrGLSL_impl.h"
 
 #endif