GrCCQuadraticShader.cpp 4.6 KB

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  1. /*
  2. * Copyright 2017 Google Inc.
  3. *
  4. * Use of this source code is governed by a BSD-style license that can be
  5. * found in the LICENSE file.
  6. */
  7. #include "src/gpu/ccpr/GrCCQuadraticShader.h"
  8. #include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
  9. #include "src/gpu/glsl/GrGLSLVertexGeoBuilder.h"
  10. void GrCCQuadraticShader::emitSetupCode(
  11. GrGLSLVertexGeoBuilder* s, const char* pts, const char** outHull4) const {
  12. s->declareGlobal(fQCoordMatrix);
  13. s->codeAppendf("%s = float2x2(1, 1, .5, 0) * inverse(float2x2(%s[2] - %s[0], %s[1] - %s[0]));",
  14. fQCoordMatrix.c_str(), pts, pts, pts, pts);
  15. s->declareGlobal(fQCoord0);
  16. s->codeAppendf("%s = %s[0];", fQCoord0.c_str(), pts);
  17. if (outHull4) {
  18. // Clip the bezier triangle by the tangent line at maximum height. Quadratics have the nice
  19. // property that maximum height always occurs at T=.5. This is a simple application for
  20. // De Casteljau's algorithm.
  21. s->codeAppend ("float2 quadratic_hull[4];");
  22. s->codeAppendf("quadratic_hull[0] = %s[0];", pts);
  23. s->codeAppendf("quadratic_hull[1] = (%s[0] + %s[1]) * .5;", pts, pts);
  24. s->codeAppendf("quadratic_hull[2] = (%s[1] + %s[2]) * .5;", pts, pts);
  25. s->codeAppendf("quadratic_hull[3] = %s[2];", pts);
  26. *outHull4 = "quadratic_hull";
  27. }
  28. }
  29. void GrCCQuadraticShader::onEmitVaryings(
  30. GrGLSLVaryingHandler* varyingHandler, GrGLSLVarying::Scope scope, SkString* code,
  31. const char* position, const char* coverage, const char* cornerCoverage, const char* wind) {
  32. fCoord_fGrad.reset(kFloat4_GrSLType, scope);
  33. varyingHandler->addVarying("coord_and_grad", &fCoord_fGrad);
  34. code->appendf("%s.xy = %s * (%s - %s);", // Quadratic coords.
  35. OutName(fCoord_fGrad), fQCoordMatrix.c_str(), position, fQCoord0.c_str());
  36. code->appendf("%s.zw = 2*bloat * float2(2 * %s.x, -1) * %s;", // Gradient.
  37. OutName(fCoord_fGrad), OutName(fCoord_fGrad), fQCoordMatrix.c_str());
  38. if (coverage) {
  39. // Coverages need full precision since distance to the opposite edge can be large.
  40. fEdge_fWind_fCorner.reset((cornerCoverage) ? kFloat4_GrSLType : kFloat2_GrSLType, scope);
  41. varyingHandler->addVarying((cornerCoverage) ? "edge_and_wind_and_corner" : "edge_and_wind",
  42. &fEdge_fWind_fCorner);
  43. code->appendf("%s.x = %s;", OutName(fEdge_fWind_fCorner), coverage);
  44. code->appendf("%s.y = %s;", OutName(fEdge_fWind_fCorner), wind);
  45. }
  46. if (cornerCoverage) {
  47. SkASSERT(coverage);
  48. code->appendf("half hull_coverage;");
  49. this->calcHullCoverage(code, OutName(fCoord_fGrad), coverage, "hull_coverage");
  50. code->appendf("%s.zw = half2(hull_coverage, 1) * %s;",
  51. OutName(fEdge_fWind_fCorner), cornerCoverage);
  52. }
  53. }
  54. void GrCCQuadraticShader::emitFragmentCoverageCode(
  55. GrGLSLFPFragmentBuilder* f, const char* outputCoverage) const {
  56. this->calcHullCoverage(&AccessCodeString(f), fCoord_fGrad.fsIn(),
  57. SkStringPrintf("%s.x", fEdge_fWind_fCorner.fsIn()).c_str(),
  58. outputCoverage);
  59. f->codeAppendf("%s *= half(%s.y);", outputCoverage, fEdge_fWind_fCorner.fsIn()); // Wind.
  60. if (kFloat4_GrSLType == fEdge_fWind_fCorner.type()) {
  61. f->codeAppendf("%s = half(%s.z * %s.w) + %s;", // Attenuated corner coverage.
  62. outputCoverage, fEdge_fWind_fCorner.fsIn(), fEdge_fWind_fCorner.fsIn(),
  63. outputCoverage);
  64. }
  65. }
  66. void GrCCQuadraticShader::calcHullCoverage(SkString* code, const char* coordAndGrad,
  67. const char* edge, const char* outputCoverage) const {
  68. code->appendf("float x = %s.x, y = %s.y;", coordAndGrad, coordAndGrad);
  69. code->appendf("float2 grad = %s.zw;", coordAndGrad);
  70. code->append ("float f = x*x - y;");
  71. code->append ("float fwidth = abs(grad.x) + abs(grad.y);");
  72. code->appendf("float curve_coverage = min(0.5 - f/fwidth, 1);");
  73. // Flat edge opposite the curve.
  74. code->appendf("float edge_coverage = min(%s, 0);", edge);
  75. // Total hull coverage.
  76. code->appendf("%s = max(half(curve_coverage + edge_coverage), 0);", outputCoverage);
  77. }
  78. void GrCCQuadraticShader::emitSampleMaskCode(GrGLSLFPFragmentBuilder* f) const {
  79. f->codeAppendf("float x = %s.x, y = %s.y;", fCoord_fGrad.fsIn(), fCoord_fGrad.fsIn());
  80. f->codeAppendf("float f = x*x - y;");
  81. f->codeAppendf("float2 grad = %s.zw;", fCoord_fGrad.fsIn());
  82. f->applyFnToMultisampleMask("f", "grad", GrGLSLFPFragmentBuilder::ScopeFlags::kTopLevel);
  83. }