| /* |
| * 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 "GrCCPRCubicShader.h" |
| |
| #include "glsl/GrGLSLFragmentShaderBuilder.h" |
| |
| void GrCCPRCubicShader::appendInputPointFetch(const GrCCPRCoverageProcessor& proc, |
| GrGLSLShaderBuilder* s, |
| const TexelBufferHandle& pointsBuffer, |
| const char* pointId) const { |
| s->appendTexelFetch(pointsBuffer, |
| SkStringPrintf("%s.x + %s", proc.instanceAttrib(), pointId).c_str()); |
| } |
| |
| void GrCCPRCubicShader::emitWind(GrGLSLShaderBuilder* s, const char* pts, |
| const char* outputWind) const { |
| |
| s->codeAppendf("float area_times_2 = determinant(float3x3(1, %s[0], " |
| "1, %s[2], " |
| "0, %s[3] - %s[1]));", |
| pts, pts, pts, pts); |
| // Drop curves that are nearly flat. The KLM math becomes unstable in this case. |
| s->codeAppendf("if (2 * abs(area_times_2) < length(%s[3] - %s[0])) {", pts, pts); |
| #ifndef SK_BUILD_FOR_MAC |
| s->codeAppend ( "return;"); |
| #else |
| // Returning from this geometry shader makes Mac very unhappy. Instead we make wind 0. |
| s->codeAppend ( "area_times_2 = 0;"); |
| #endif |
| s->codeAppend ("}"); |
| s->codeAppendf("%s = sign(area_times_2);", outputWind); |
| } |
| |
| void GrCCPRCubicShader::emitSetupCode(GrGLSLShaderBuilder* s, const char* pts, |
| const char* segmentId, const char* wind, |
| GeometryVars* vars) const { |
| // Evaluate the cubic at T=.5 for an mid-ish point. |
| s->codeAppendf("float2 midpoint = %s * float4(.125, .375, .375, .125);", pts); |
| |
| // 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 ("float4 K, L, M;"); |
| s->codeAppend ("float2 l, m;"); |
| s->codeAppend ("float discr = 3*D2*D2 - 4*D1*D3;"); |
| if (CubicType::kSerpentine == fCubicType) { |
| // This math also works out for the "cusp" and "cusp at infinity" cases. |
| s->codeAppend ("float q = sqrt(max(3*discr, 0));"); |
| s->codeAppend ("q = 3*D2 + (D2 >= 0 ? q : -q);"); |
| s->codeAppend ("l.ts = normalize(float2(q, 6*D1));"); |
| s->codeAppend ("m.ts = discr <= 0 ? l.ts : normalize(float2(2*D3, q));"); |
| s->codeAppend ("K = float4(0, l.s * m.s, -l.t * m.s - m.t * l.s, l.t * m.t);"); |
| s->codeAppend ("L = float4(-1,3,-3,1) * l.ssst * l.sstt * l.sttt;"); |
| s->codeAppend ("M = float4(-1,3,-3,1) * m.ssst * m.sstt * m.sttt;"); |
| } else { |
| s->codeAppend ("float q = sqrt(max(-discr, 0));"); |
| s->codeAppend ("q = D2 + (D2 >= 0 ? q : -q);"); |
| s->codeAppend ("l.ts = normalize(float2(q, 2*D1));"); |
| s->codeAppend ("m.ts = discr >= 0 ? l.ts : normalize(float2(2 * (D2*D2 - D3*D1), D1*q));"); |
| s->codeAppend ("float4 lxm = float4(l.s * m.s, l.s * m.t, l.t * m.s, l.t * m.t);"); |
| s->codeAppend ("K = float4(0, lxm.x, -lxm.y - lxm.z, lxm.w);"); |
| s->codeAppend ("L = float4(-1,1,-1,1) * l.sstt * (lxm.xyzw + float4(0, 2*lxm.zy, 0));"); |
| s->codeAppend ("M = float4(-1,1,-1,1) * m.sstt * (lxm.xzyw + float4(0, 2*lxm.yz, 0));"); |
| } |
| 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()); |
| |
| // Orient the KLM matrix so we fill the correct side of the curve. |
| 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], 0, " |
| "0, 0, orientation[1]);", fKLMMatrix.c_str()); |
| |
| // 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, segmentId, vars); |
| } |
| |
| GrCCPRCubicShader::WindHandling |
| GrCCPRCubicShader::onEmitVaryings(GrGLSLVaryingHandler* varyingHandler, SkString* code, |
| const char* position, const char* /*coverage*/, |
| const char* /*wind*/) { |
| 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);", fKLMD.gsOut()); |
| |
| this->onEmitVaryings(varyingHandler, code); |
| return WindHandling::kNotHandled; |
| } |
| |
| void GrCCPRCubicHullShader::onEmitSetupCode(GrGLSLShaderBuilder* s, const char* /*pts*/, |
| const char* /*wedgeId*/, GeometryVars* vars) const { |
| // "midpoint" was just defined by the base class. |
| vars->fHullVars.fAlternateMidpoint = "midpoint"; |
| } |
| |
| void GrCCPRCubicHullShader::onEmitVaryings(GrGLSLVaryingHandler* varyingHandler, SkString* code) { |
| // "klm" was just defined by the base class. |
| varyingHandler->addVarying("grad_matrix", &fGradMatrix); |
| code->appendf("%s[0] = 3 * klm[0] * %s[0].xy;", fGradMatrix.gsOut(), fKLMMatrix.c_str()); |
| code->appendf("%s[1] = -klm[1] * %s[2].xy - klm[2] * %s[1].xy;", |
| fGradMatrix.gsOut(), fKLMMatrix.c_str(), fKLMMatrix.c_str()); |
| } |
| |
| void GrCCPRCubicHullShader::onEmitFragmentCode(GrGLSLPPFragmentBuilder* 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()); |
| 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 closing edge. |
| } |
| |
| void GrCCPRCubicCornerShader::onEmitSetupCode(GrGLSLShaderBuilder* s, const char* pts, |
| const char* cornerId, GeometryVars* vars) const { |
| s->codeAppendf("float2 corner = %s[%s * 3];", pts, cornerId); |
| vars->fCornerVars.fPoint = "corner"; |
| } |
| |
| void GrCCPRCubicCornerShader::onEmitVaryings(GrGLSLVaryingHandler* varyingHandler, SkString* code) { |
| varyingHandler->addFlatVarying("dklmddx", &fdKLMDdx); |
| code->appendf("%s = float4(%s[0].x, %s[1].x, %s[2].x, %s.x);", |
| fdKLMDdx.gsOut(), fKLMMatrix.c_str(), fKLMMatrix.c_str(), |
| fKLMMatrix.c_str(), fEdgeDistanceEquation.c_str()); |
| |
| varyingHandler->addFlatVarying("dklmddy", &fdKLMDdy); |
| code->appendf("%s = float4(%s[0].y, %s[1].y, %s[2].y, %s.y);", |
| fdKLMDdy.gsOut(), fKLMMatrix.c_str(), fKLMMatrix.c_str(), |
| fKLMMatrix.c_str(), fEdgeDistanceEquation.c_str()); |
| } |
| |
| void GrCCPRCubicCornerShader::onEmitFragmentCode(GrGLSLPPFragmentBuilder* 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. |
| f->codeAppendf("float k = %s.x, l = %s.y, m = %s.z, d = %s.w;", |
| fKLMD.fsIn(), fKLMD.fsIn(), fKLMD.fsIn(), fKLMD.fsIn()); |
| 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 ("}"); |
| } |
