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Diffstat (limited to 'src/gpu/ccpr/GrCCConicShader.cpp')
-rw-r--r-- | src/gpu/ccpr/GrCCConicShader.cpp | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/src/gpu/ccpr/GrCCConicShader.cpp b/src/gpu/ccpr/GrCCConicShader.cpp new file mode 100644 index 0000000000..01568de437 --- /dev/null +++ b/src/gpu/ccpr/GrCCConicShader.cpp @@ -0,0 +1,93 @@ +/* + * Copyright 2018 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#include "GrCCConicShader.h" + +#include "glsl/GrGLSLFragmentShaderBuilder.h" +#include "glsl/GrGLSLVertexGeoBuilder.h" + +void GrCCConicShader::emitSetupCode(GrGLSLVertexGeoBuilder* s, const char* pts, const char* wind, + const char** outHull4) const { + // K is distance from the line P2 -> P0. L is distance from the line P0 -> P1, scaled by 2w. + // M is distance from the line P1 -> P2, scaled by 2w. We do this in a space where P1=0. + s->declareGlobal(fKLMMatrix); + s->codeAppendf("float x0 = %s[0].x - %s[1].x, x2 = %s[2].x - %s[1].x;", pts, pts, pts, pts); + s->codeAppendf("float y0 = %s[0].y - %s[1].y, y2 = %s[2].y - %s[1].y;", pts, pts, pts, pts); + s->codeAppendf("float w = %s[3].x;", pts); + s->codeAppendf("%s = float3x3(y2 - y0, x0 - x2, x2*y0 - x0*y2, " + "2*w * float2(+y0, -x0), 0, " + "2*w * float2(-y2, +x2), 0);", fKLMMatrix.c_str()); + + s->declareGlobal(fControlPoint); + s->codeAppendf("%s = %s[1];", fControlPoint.c_str(), pts); + + // Scale KLM by the inverse Manhattan width of K. This allows K to double as the flat opposite + // edge AA. kwidth will not be 0 because we cull degenerate conics on the CPU. + s->codeAppendf("float kwidth = 2*bloat * %s * (abs(%s[0].x) + abs(%s[0].y));", + wind, fKLMMatrix.c_str(), fKLMMatrix.c_str()); + s->codeAppendf("%s *= 1/kwidth;", fKLMMatrix.c_str()); + + if (outHull4) { + // Clip the conic triangle by the tangent line at maximum height. Conics have the nice + // property that maximum height always occurs at T=.5. This is a simple application for + // De Casteljau's algorithm. + s->codeAppendf("float2 p1w = %s[1]*w;", pts); + s->codeAppend ("float r = 1 / (1 + w);"); + s->codeAppendf("float2 conic_hull[4] = float2[4](%s[0], " + "(%s[0] + p1w) * r, " + "(p1w + %s[2]) * r, " + "%s[2]);", pts, pts, pts, pts); + *outHull4 = "conic_hull"; + } +} + +void GrCCConicShader::onEmitVaryings(GrGLSLVaryingHandler* varyingHandler, + GrGLSLVarying::Scope scope, SkString* code, + const char* position, const char* coverage, + const char* cornerCoverage) { + fKLM_fWind.reset(kFloat4_GrSLType, scope); + varyingHandler->addVarying("klm_and_wind", &fKLM_fWind); + code->appendf("float3 klm = float3(%s - %s, 1) * %s;", + position, fControlPoint.c_str(), fKLMMatrix.c_str()); + code->appendf("%s.xyz = klm;", OutName(fKLM_fWind)); + code->appendf("%s.w = %s;", OutName(fKLM_fWind), coverage); // coverage == wind. + + fGrad_fCorner.reset(cornerCoverage ? kFloat4_GrSLType : kFloat2_GrSLType, scope); + varyingHandler->addVarying(cornerCoverage ? "grad_and_corner" : "grad", &fGrad_fCorner); + code->appendf("%s.xy = 2*bloat * (float3x2(%s) * float3(2*klm[0], -klm[2], -klm[1]));", + OutName(fGrad_fCorner), fKLMMatrix.c_str()); + + if (cornerCoverage) { + code->appendf("half hull_coverage;"); + this->calcHullCoverage(code, "klm", OutName(fGrad_fCorner), "hull_coverage"); + code->appendf("%s.zw = half2(hull_coverage, 1) * %s;", + OutName(fGrad_fCorner), cornerCoverage); + } +} + +void GrCCConicShader::onEmitFragmentCode(GrGLSLFPFragmentBuilder* f, + const char* outputCoverage) const { + this->calcHullCoverage(&AccessCodeString(f), fKLM_fWind.fsIn(), fGrad_fCorner.fsIn(), + outputCoverage); + f->codeAppendf("%s *= %s.w;", outputCoverage, fKLM_fWind.fsIn()); // Wind. + + if (kFloat4_GrSLType == fGrad_fCorner.type()) { + f->codeAppendf("%s = %s.z * %s.w + %s;", // Attenuated corner coverage. + outputCoverage, fGrad_fCorner.fsIn(), fGrad_fCorner.fsIn(), + outputCoverage); + } +} + +void GrCCConicShader::calcHullCoverage(SkString* code, const char* klm, const char* grad, + const char* outputCoverage) const { + code->appendf("float k = %s.x, l = %s.y, m = %s.z;", klm, klm, klm); + code->append ("float f = k*k - l*m;"); + code->appendf("float fwidth = abs(%s.x) + abs(%s.y);", grad, grad); + code->appendf("%s = min(0.5 - f/fwidth, 1);", outputCoverage); // Curve coverage. + code->append ("half d = min(k - 0.5, 0);"); // K doubles as the flat opposite edge's AA. + code->appendf("%s = max(%s + d, 0);", outputCoverage, outputCoverage); // Total hull coverage. +} |