1 /*
2 * Copyright 2020 Google LLC.
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
8 #include "src/gpu/tessellate/GrFillPathShader.h"
9
10 #include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
11 #include "src/gpu/glsl/GrGLSLGeometryProcessor.h"
12 #include "src/gpu/glsl/GrGLSLVarying.h"
13 #include "src/gpu/glsl/GrGLSLVertexGeoBuilder.h"
14
15 class GrFillPathShader::Impl : public GrGLSLGeometryProcessor {
16 public:
onEmitCode(EmitArgs & args,GrGPArgs * gpArgs)17 void onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) override {
18 auto& shader = args.fGP.cast<GrFillPathShader>();
19
20 const char* viewMatrix;
21 fViewMatrixUniform = args.fUniformHandler->addUniform(
22 kVertex_GrShaderFlag, kFloat3x3_GrSLType, "view_matrix", &viewMatrix);
23
24 args.fVaryingHandler->emitAttributes(shader);
25
26 args.fVertBuilder->codeAppend("float2 localcoord, vertexpos;");
27 shader.emitVertexCode(this, args.fVertBuilder, viewMatrix, args.fUniformHandler);
28
29 this->emitTransforms(args.fVertBuilder, args.fVaryingHandler, args.fUniformHandler,
30 GrShaderVar("localcoord", kFloat2_GrSLType),
31 args.fFPCoordTransformHandler);
32
33 gpArgs->fPositionVar.set(kFloat2_GrSLType, "vertexpos");
34
35 const char* color;
36 fColorUniform = args.fUniformHandler->addUniform(
37 kFragment_GrShaderFlag, kHalf4_GrSLType, "color", &color);
38
39 args.fFragBuilder->codeAppendf("%s = %s;", args.fOutputColor, color);
40 args.fFragBuilder->codeAppendf("%s = half4(1);", args.fOutputCoverage);
41 }
42
setData(const GrGLSLProgramDataManager & pdman,const GrPrimitiveProcessor & primProc,const CoordTransformRange & transformRange)43 void setData(const GrGLSLProgramDataManager& pdman, const GrPrimitiveProcessor& primProc,
44 const CoordTransformRange& transformRange) override {
45 const GrFillPathShader& shader = primProc.cast<GrFillPathShader>();
46 pdman.setSkMatrix(fViewMatrixUniform, shader.viewMatrix());
47
48 const SkPMColor4f& color = shader.fColor;
49 pdman.set4f(fColorUniform, color.fR, color.fG, color.fB, color.fA);
50
51 if (fPathBoundsUniform.isValid()) {
52 const SkRect& b = primProc.cast<GrFillBoundingBoxShader>().pathBounds();
53 pdman.set4f(fPathBoundsUniform, b.left(), b.top(), b.right(), b.bottom());
54 }
55
56 this->setTransformDataHelper(SkMatrix::I(), pdman, transformRange);
57 }
58
59 GrGLSLUniformHandler::UniformHandle fViewMatrixUniform;
60 GrGLSLUniformHandler::UniformHandle fColorUniform;
61 GrGLSLUniformHandler::UniformHandle fPathBoundsUniform;
62 };
63
createGLSLInstance(const GrShaderCaps &) const64 GrGLSLPrimitiveProcessor* GrFillPathShader::createGLSLInstance(const GrShaderCaps&) const {
65 return new Impl;
66 }
67
emitVertexCode(Impl *,GrGLSLVertexBuilder * v,const char * viewMatrix,GrGLSLUniformHandler * uniformHandler) const68 void GrFillTriangleShader::emitVertexCode(Impl*, GrGLSLVertexBuilder* v, const char* viewMatrix,
69 GrGLSLUniformHandler* uniformHandler) const {
70 v->codeAppendf(R"(
71 localcoord = input_point;
72 vertexpos = (%s * float3(localcoord, 1)).xy;)", viewMatrix);
73 }
74
emitVertexCode(Impl *,GrGLSLVertexBuilder * v,const char * viewMatrix,GrGLSLUniformHandler * uniformHandler) const75 void GrFillCubicHullShader::emitVertexCode(Impl*, GrGLSLVertexBuilder* v, const char* viewMatrix,
76 GrGLSLUniformHandler* uniformHandler) const {
77 v->codeAppend(R"(
78 float4x2 P = float4x2(input_points_0_1, input_points_2_3);
79
80 // Translate the points to v0..3 where v0=0.
81 float2 v1 = P[1] - P[0], v2 = P[2] - P[0], v3 = P[3] - P[0];
82
83 // Reorder the points so v2 bisects v1 and v3.
84 if (sign(determinant(float2x2(v2,v1))) == sign(determinant(float2x2(v2,v3)))) {
85 float2 tmp = P[2];
86 if (sign(determinant(float2x2(v1,v2))) != sign(determinant(float2x2(v1,v3)))) {
87 P[2] = P[1]; // swap(P2, P1)
88 P[1] = tmp;
89 } else {
90 P[2] = P[3]; // swap(P2, P3)
91 P[3] = tmp;
92 }
93 }
94
95 // Find the "turn direction" of each corner and net turn direction.
96 float4 dir;
97 float netdir = 0.0;
98 for (int i = 0; i < 4; ++i) {
99 float2 prev = P[i] - P[(i + 3) & 3], next = P[(i + 1) & 3] - P[i];
100 dir[i] = sign(determinant(float2x2(prev, next)));
101 netdir += dir[i];
102 }
103
104 // sk_VertexID comes in fan order. Convert to strip order.
105 int vertexidx = sk_VertexID;
106 vertexidx ^= vertexidx >> 1;
107
108 // Remove the non-convex vertex, if any.
109 if (dir[vertexidx] != sign(netdir)) {
110 vertexidx = (vertexidx + 1) & 3;
111 }
112
113 localcoord = P[vertexidx];)");
114
115 v->codeAppendf("vertexpos = (%s * float3(localcoord, 1)).xy;", viewMatrix);
116 }
117
emitVertexCode(Impl * impl,GrGLSLVertexBuilder * v,const char * viewMatrix,GrGLSLUniformHandler * uniformHandler) const118 void GrFillBoundingBoxShader::emitVertexCode(Impl* impl, GrGLSLVertexBuilder* v,
119 const char* viewMatrix,
120 GrGLSLUniformHandler* uniformHandler) const {
121 const char* pathBounds;
122 impl->fPathBoundsUniform = uniformHandler->addUniform(
123 kVertex_GrShaderFlag, kFloat4_GrSLType, "path_bounds", &pathBounds);
124
125 v->codeAppendf(R"(
126 // Use sk_VertexID and uniforms (instead of vertex data) to find vertex positions.
127 float2 T = float2(sk_VertexID & 1, sk_VertexID >> 1);
128 localcoord = mix(%s.xy, %s.zw, T);
129 vertexpos = (%s * float3(localcoord, 1)).xy;
130
131 // Outset to avoid possible T-junctions with extreme edges of the path.
132 float2x2 M2 = float2x2(%s);
133 float2 devoutset = .25 * sign(M2 * (T - .5));
134 localcoord += inverse(M2) * devoutset;
135 vertexpos += devoutset;)", pathBounds, pathBounds, viewMatrix, viewMatrix);
136 }
137