1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "GrCCCubicShader.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "glsl/GrGLSLVertexGeoBuilder.h"
using Shader = GrCCCoverageProcessor::Shader;
void GrCCCubicShader::emitSetupCode(GrGLSLVertexGeoBuilder* s, const char* pts,
const char* repetitionID, const char* wind,
GeometryVars* vars) const {
// Find the cubic's power basis coefficients.
s->codeAppendf("float2x4 C = float4x4(-1, 3, -3, 1, "
" 3, -6, 3, 0, "
"-3, 3, 0, 0, "
" 1, 0, 0, 0) * transpose(%s);", pts);
// Find the cubic's inflection function.
s->codeAppend ("float D3 = +determinant(float2x2(C[0].yz, C[1].yz));");
s->codeAppend ("float D2 = -determinant(float2x2(C[0].xz, C[1].xz));");
s->codeAppend ("float D1 = +determinant(float2x2(C));");
// Calculate the KLM matrix.
s->declareGlobal(fKLMMatrix);
s->codeAppend ("float discr = 3*D2*D2 - 4*D1*D3;");
s->codeAppend ("float x = discr >= 0 ? 3 : 1;");
s->codeAppend ("float q = sqrt(x * abs(discr));");
s->codeAppend ("q = x*D2 + (D2 >= 0 ? q : -q);");
s->codeAppend ("float2 l, m;");
s->codeAppend ("l.ts = normalize(float2(q, 2*x * D1));");
s->codeAppend ("m.ts = normalize(float2(2, q) * (discr >= 0 ? float2(D3, 1) "
": float2(D2*D2 - D3*D1, D1)));");
s->codeAppend ("float4 K;");
s->codeAppend ("float4 lm = l.sstt * m.stst;");
s->codeAppend ("K = float4(0, lm.x, -lm.y - lm.z, lm.w);");
s->codeAppend ("float4 L, M;");
s->codeAppend ("lm.yz += 2*lm.zy;");
s->codeAppend ("L = float4(-1,x,-x,1) * l.sstt * (discr >= 0 ? l.ssst * l.sttt : lm);");
s->codeAppend ("M = float4(-1,x,-x,1) * m.sstt * (discr >= 0 ? m.ssst * m.sttt : lm.xzyw);");
s->codeAppend ("short middlerow = abs(D2) > abs(D1) ? 2 : 1;");
s->codeAppend ("float3x3 CI = inverse(float3x3(C[0][0], C[0][middlerow], C[0][3], "
"C[1][0], C[1][middlerow], C[1][3], "
" 0, 0, 1));");
s->codeAppendf("%s = CI * float3x3(K[0], K[middlerow], K[3], "
"L[0], L[middlerow], L[3], "
"M[0], M[middlerow], M[3]);", fKLMMatrix.c_str());
// Evaluate the cubic at T=.5 for a mid-ish point.
s->codeAppendf("float2 midpoint = %s * float4(.125, .375, .375, .125);", pts);
// Orient the KLM matrix so L & M have matching signs on the side of the curve we wish to fill.
// We give L & M both the same sign as wind, in order to pass this value to the fragment shader.
// (Cubics are pre-chopped such that L & M do not change sign within any individual segment).
s->codeAppendf("float2 orientation = sign(float3(midpoint, 1) * float2x3(%s[1], %s[2]));",
fKLMMatrix.c_str(), fKLMMatrix.c_str());
s->codeAppendf("%s *= float3x3(orientation[0] * orientation[1], 0, 0, "
"0, orientation[0] * %s, 0, "
"0, 0, orientation[1] * %s);", fKLMMatrix.c_str(), wind, wind);
// Determine the amount of additional coverage to subtract out for the flat edge (P3 -> P0).
s->declareGlobal(fEdgeDistanceEquation);
s->codeAppendf("short edgeidx0 = %s > 0 ? 3 : 0;", wind);
s->codeAppendf("float2 edgept0 = %s[edgeidx0];", pts);
s->codeAppendf("float2 edgept1 = %s[3 - edgeidx0];", pts);
Shader::EmitEdgeDistanceEquation(s, "edgept0", "edgept1", fEdgeDistanceEquation.c_str());
this->onEmitSetupCode(s, pts, repetitionID, vars);
}
void GrCCCubicShader::onEmitVaryings(GrGLSLVaryingHandler* varyingHandler,
GrGLSLVarying::Scope scope, SkString* code,
const char* position, const char* inputCoverage,
const char* /*wind*/) {
SkASSERT(!inputCoverage);
fKLMD.reset(kFloat4_GrSLType, scope);
varyingHandler->addVarying("klmd", &fKLMD);
code->appendf("float3 klm = float3(%s, 1) * %s;", position, fKLMMatrix.c_str());
code->appendf("float d = dot(float3(%s, 1), %s);", position, fEdgeDistanceEquation.c_str());
code->appendf("%s = float4(klm, d);", OutName(fKLMD));
this->onEmitVaryings(varyingHandler, scope, code);
}
void GrCCCubicShader::onEmitFragmentCode(GrGLSLFPFragmentBuilder* f,
const char* outputCoverage) const {
f->codeAppendf("float k = %s.x, l = %s.y, m = %s.z, d = %s.w;",
fKLMD.fsIn(), fKLMD.fsIn(), fKLMD.fsIn(), fKLMD.fsIn());
this->emitCoverage(f, outputCoverage);
// Wind is the sign of both L and/or M. Take the sign of whichever has the larger magnitude.
// (In reality, either would be fine because we chop cubics with more than a half pixel of
// padding around the L & M lines, so neither should approach zero.)
f->codeAppend ("half wind = sign(l + m);");
f->codeAppendf("%s *= wind;", outputCoverage);
}
void GrCCCubicHullShader::onEmitVaryings(GrGLSLVaryingHandler* varyingHandler,
GrGLSLVarying::Scope scope, SkString* code) {
fGradMatrix.reset(kFloat2x2_GrSLType, scope);
varyingHandler->addVarying("grad_matrix", &fGradMatrix);
// "klm" was just defined by the base class.
code->appendf("%s[0] = 3 * klm[0] * %s[0].xy;", OutName(fGradMatrix), fKLMMatrix.c_str());
code->appendf("%s[1] = -klm[1] * %s[2].xy - klm[2] * %s[1].xy;",
OutName(fGradMatrix), fKLMMatrix.c_str(), fKLMMatrix.c_str());
}
void GrCCCubicHullShader::emitCoverage(GrGLSLFPFragmentBuilder* f,
const char* outputCoverage) const {
// k,l,m,d are defined by the base class.
f->codeAppend ("float f = k*k*k - l*m;");
f->codeAppendf("float2 grad_f = %s * float2(k, 1);", fGradMatrix.fsIn());
f->codeAppendf("%s = clamp(0.5 - f * inversesqrt(dot(grad_f, grad_f)), 0, 1);", outputCoverage);
f->codeAppendf("%s += min(d, 0);", outputCoverage); // Flat edge opposite the curve.
}
void GrCCCubicCornerShader::onEmitSetupCode(GrGLSLVertexGeoBuilder* s, const char* pts,
const char* repetitionID, GeometryVars* vars) const {
s->codeAppendf("float2 corner = %s[%s * 3];", pts, repetitionID);
vars->fCornerVars.fPoint = "corner";
}
void GrCCCubicCornerShader::onEmitVaryings(GrGLSLVaryingHandler* varyingHandler,
GrGLSLVarying::Scope scope, SkString* code) {
using Interpolation = GrGLSLVaryingHandler::Interpolation;
fdKLMDdx.reset(kFloat4_GrSLType, scope);
varyingHandler->addVarying("dklmddx", &fdKLMDdx, Interpolation::kCanBeFlat);
code->appendf("%s = float4(%s[0].x, %s[1].x, %s[2].x, %s.x);",
OutName(fdKLMDdx), fKLMMatrix.c_str(), fKLMMatrix.c_str(),
fKLMMatrix.c_str(), fEdgeDistanceEquation.c_str());
fdKLMDdy.reset(kFloat4_GrSLType, scope);
varyingHandler->addVarying("dklmddy", &fdKLMDdy, Interpolation::kCanBeFlat);
code->appendf("%s = float4(%s[0].y, %s[1].y, %s[2].y, %s.y);",
OutName(fdKLMDdy), fKLMMatrix.c_str(), fKLMMatrix.c_str(),
fKLMMatrix.c_str(), fEdgeDistanceEquation.c_str());
}
void GrCCCubicCornerShader::emitCoverage(GrGLSLFPFragmentBuilder* f,
const char* outputCoverage) const {
f->codeAppendf("float2x4 grad_klmd = float2x4(%s, %s);", fdKLMDdx.fsIn(), fdKLMDdy.fsIn());
// Erase what the previous hull shader wrote. We don't worry about the two corners falling on
// the same pixel because those cases should have been weeded out by this point.
// k,l,m,d are defined by the base class.
f->codeAppend ("float f = k*k*k - l*m;");
f->codeAppend ("float2 grad_f = float3(3*k*k, -m, -l) * float2x3(grad_klmd);");
f->codeAppendf("%s = -clamp(0.5 - f * inversesqrt(dot(grad_f, grad_f)), 0, 1);",
outputCoverage);
f->codeAppendf("%s -= d;", outputCoverage);
// Use software msaa to estimate actual coverage at the corner pixels.
const int sampleCount = Shader::DefineSoftSampleLocations(f, "samples");
f->codeAppendf("float4 klmd_center = float4(%s.xyz, %s.w + 0.5);",
fKLMD.fsIn(), fKLMD.fsIn());
f->codeAppendf("for (int i = 0; i < %i; ++i) {", sampleCount);
f->codeAppend ( "float4 klmd = grad_klmd * samples[i] + klmd_center;");
f->codeAppend ( "half f = klmd.y * klmd.z - klmd.x * klmd.x * klmd.x;");
f->codeAppendf( "%s += all(greaterThan(half4(f, klmd.y, klmd.z, klmd.w), "
"half4(0))) ? %f : 0;",
outputCoverage, 1.0 / sampleCount);
f->codeAppend ("}");
}
|
