| /* |
| * 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 ("}"); |
| } |