commit 7da048b5e8f17374bcd5baf48539eaa7ebe40e5c
author Jim Van Verth <jvanverth@google.com> Tue Oct 29 13:28:14 2019 -0400
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Wed Oct 30 13:40:16 2019 +0000
tree d4d906ae66f9e8003c8dbc0ac575df9f5ca780cc
parent ebdae1144978a3943d76d9e0af2a7ffbbaf88937

Use texture for shadow falloff

Bug: b/142333639
Change-Id: I5c5bf4da0e2bb5f1b4233681dee305cf381c3e2a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/250096
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>

src/gpu/effects/GrShadowGeoProc.cpp

diff --git a/src/gpu/effects/GrShadowGeoProc.cpp b/src/gpu/effects/GrShadowGeoProc.cpp
index 5af096c..0b8ebdc 100644
--- a/src/gpu/effects/GrShadowGeoProc.cpp
+++ b/src/gpu/effects/GrShadowGeoProc.cpp
@@ -43,12 +43,11 @@
                              args.fFPCoordTransformHandler);
 
         fragBuilder->codeAppend("half d = length(shadowParams.xy);");
-        fragBuilder->codeAppend("half distance = shadowParams.z * (1.0 - d);");
-
-        fragBuilder->codeAppend("half factor = 1.0 - clamp(distance, 0.0, 1.0);");
-        fragBuilder->codeAppend("factor = exp(-factor * factor * 4.0) - 0.018;");
-        fragBuilder->codeAppendf("%s = half4(factor);",
-                                 args.fOutputCoverage);
+        fragBuilder->codeAppend("float2 uv = float2(shadowParams.z * (1.0 - d), 0.5);");
+        fragBuilder->codeAppend("half factor = ");
+        fragBuilder->appendTextureLookup(args.fTexSamplers[0], "uv", kFloat2_GrSLType);
+        fragBuilder->codeAppend(".a;");
+        fragBuilder->codeAppendf("%s = half4(factor);", args.fOutputCoverage);
     }
 
     void setData(const GrGLSLProgramDataManager& pdman, const GrPrimitiveProcessor& proc,
@@ -62,11 +61,17 @@
 
 ///////////////////////////////////////////////////////////////////////////////
 
-GrRRectShadowGeoProc::GrRRectShadowGeoProc() : INHERITED(kGrRRectShadowGeoProc_ClassID) {
+GrRRectShadowGeoProc::GrRRectShadowGeoProc(const GrTextureProxy* lut)
+        : INHERITED(kGrRRectShadowGeoProc_ClassID) {
     fInPosition = {"inPosition", kFloat2_GrVertexAttribType, kFloat2_GrSLType};
     fInColor = {"inColor", kUByte4_norm_GrVertexAttribType, kHalf4_GrSLType};
     fInShadowParams = {"inShadowParams", kFloat3_GrVertexAttribType, kHalf3_GrSLType};
     this->setVertexAttributes(&fInPosition, 3);
+
+    SkASSERT(lut);
+    fLUTTextureSampler.reset(GrSamplerState::ClampBilerp(), lut->backendFormat(),
+                             lut->textureSwizzle());
+    this->setTextureSamplerCnt(1);
 }
 
 GrGLSLPrimitiveProcessor* GrRRectShadowGeoProc::createGLSLInstance(const GrShaderCaps&) const {
@@ -79,6 +84,6 @@
 
 #if GR_TEST_UTILS
 sk_sp<GrGeometryProcessor> GrRRectShadowGeoProc::TestCreate(GrProcessorTestData* d) {
-    return GrRRectShadowGeoProc::Make();
+    return GrRRectShadowGeoProc::Make(d->textureProxy(GrProcessorUnitTest::kAlphaTextureIdx).get());
 }
 #endif