Improve join between the two RRects in SkRRectsGaussianEdgeShader

src/effects/SkRRectsGaussianEdgeShader.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkRRectsGaussianEdgeShader.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
@@ skipping 108 matching lines @@
             case kCircle_Mode:
                 fragBuilder->codeAppendf("%s = clamp((%s.%c - length(delta))/%s, 0.0, 1.0);",
                                          outputName, sizesName, indices[0], radName);
                 break;
             case kRect_Mode:
                 fragBuilder->codeAppendf(
                     "vec2 rectDist = vec2(1.0 - clamp((%s.%c - abs(delta.x))/%s, 0.0, 1.0),"
                                          "1.0 - clamp((%s.%c - abs(delta.y))/%s, 0.0, 1.0));",
                     sizesName, indices[0], radName,
                     sizesName, indices[1], radName);
-                fragBuilder->codeAppendf("%s = 1.0 - length(rectDist);", outputName);
+                fragBuilder->codeAppendf("%s = clamp(1.0 - length(rectDist), 0.0, 1.0);",
+                                         outputName);
                 break;
             case kSimpleCircular_Mode:
                 // For the circular round rect we first compute the distance
                 // to the rect. Then we compute a multiplier that is 1 if the
                 // point is in one of the circular corners. We then compute the
                 // distance from the corner and then use the multiplier to mask
                 // between the two distances.
                 fragBuilder->codeAppendf("float xDist = clamp((%s.%c - abs(delta.x))/%s,"
                                                              " 0.0, 1.0);",
                                          sizesName, indices[0], radName);
@@ skipping 55 matching lines @@
                                radUniName, "firstDist", "xy");
             fragBuilder->codeAppend("}");
 
             fragBuilder->codeAppend("float secondDist;");
             fragBuilder->codeAppend("{");
             this->emitModeCode(fp.secondMode(), fragBuilder,
                                positionsUniName, sizesUniName, radiiUniName,
                                radUniName, "secondDist", "zw");
             fragBuilder->codeAppend("}");
 
-            fragBuilder->codeAppendf("float dist = %s * firstDist * secondDist;", radUniName);
+            fragBuilder->codeAppend("vec2 distVec = vec2(1.0 - firstDist, 1.0 - secondDist);");
 
             // Finally use the distance to apply the Gaussian edge
-            // TODO: we undo the multiply by the radius here - we should just skip both
-            fragBuilder->codeAppendf("float factor = 1.0 - clamp(dist/%s, 0.0, 1.0);", radUniName);
+            fragBuilder->codeAppend("float factor = clamp(length(distVec), 0.0, 1.0);");
             fragBuilder->codeAppend("factor = exp(-factor * factor * 4.0) - 0.018;");
             fragBuilder->codeAppendf("%s = factor*%s;",
                                      args.fOutputColor, args.fInputColor);
         }
 
         static void GenKey(const GrProcessor& proc, const GrGLSLCaps&,
                            GrProcessorKeyBuilder* b) {
             const RRectsGaussianEdgeFP& fp = proc.cast<RRectsGaussianEdgeFP>();
 
             b->add32(fp.firstMode() | (fp.secondMode() << 4));
@@ skipping 200 matching lines @@
     return sk_make_sp<SkRRectsGaussianEdgeShaderImpl>(first, second, radius);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkRRectsGaussianEdgeShader)
 SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkRRectsGaussianEdgeShaderImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
 
 ///////////////////////////////////////////////////////////////////////////////