GrFP can express distance vector field req., program builder declares variable for it

src/gpu/glsl/GrGLSLProgramBuilder.cpp

Index: src/gpu/glsl/GrGLSLProgramBuilder.cpp
diff --git a/src/gpu/glsl/GrGLSLProgramBuilder.cpp b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
index 31d1de29b3ba89da5a7b22a0fc2b716e9337b51a..2a828c4e2986bc76e52f69777f15e28bc0a9af73 100644
--- a/src/gpu/glsl/GrGLSLProgramBuilder.cpp
+++ b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
@@ -87,6 +87,14 @@ void GrGLSLProgramBuilder::emitAndInstallPrimProc(const GrPrimitiveProcessor& pr
     this->nameExpression(outputColor, "outputColor");
     this->nameExpression(outputCoverage, "outputCoverage");
 
+    if (this->fPipeline.usesDistanceVectorField()) {
+        SkString outputDistanceVectorStr;
+        this->nameVariable(&outputDistanceVectorStr, '\0', "outputDistanceVector");

[egdaniel, 2016/07/12 13:46:42]

I think I would prefer hard coding the name we want to use into
GLSLFragmentShaderBuilder instead of us telling the fragment shader what the
name should be.

[dvonbeck, 2016/07/13 15:17:13]

The thing is, the Geometry Processors get their variable names mangled. That's
why I'm running it through the nameVariable method.

[egdaniel, 2016/07/13 15:47:02]

I don't think there is any need for mangling the variable here. We do a similar
thing when we need to declare the the outColor variable. See 
DeclaredColorOutputName()

[dvonbeck, 2016/07/13 16:57:49]

Done.

+        fFS.enableDistanceVector(outputDistanceVectorStr);
+

[robertphillips, 2016/07/11 17:55:40]

Maybe emit a comment:

// Un-normalized vector to the closed geometric edge (in source space)

?

[dvonbeck, 2016/07/13 15:17:13]

Done.

+        fFS.codeAppendf("vec2 %s = vec2(0.0, 0.0);", fFS.distanceVectorName());
+    }
+
     // Enclose custom code in a block to avoid namespace conflicts
     SkString openBrace;
     openBrace.printf("{ // Stage %d, %s\n", fStageIndex, proc.name());