/* * 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 "GrCCPRQuadraticProcessor.h" #include "glsl/GrGLSLFragmentShaderBuilder.h" #include "glsl/GrGLSLGeometryShaderBuilder.h" #include "glsl/GrGLSLVertexShaderBuilder.h" void GrCCPRQuadraticProcessor::onEmitVertexShader(const GrCCPRCoverageProcessor& proc, GrGLSLVertexBuilder* v, const TexelBufferHandle& pointsBuffer, const char* atlasOffset, const char* rtAdjust, GrGPArgs* gpArgs) const { v->codeAppend ("highp float2 self = "); v->appendTexelFetch(pointsBuffer, SkStringPrintf("%s.x + sk_VertexID", proc.instanceAttrib()).c_str()); v->codeAppendf(".xy + %s;", atlasOffset); gpArgs->fPositionVar.set(kVec2f_GrSLType, "self"); } void GrCCPRQuadraticProcessor::emitWind(GrGLSLGeometryBuilder* g, const char* rtAdjust, const char* outputWind) const { // We will define bezierpts in onEmitGeometryShader. g->codeAppend ("highp float area_times_2 = " "determinant(float2x2(bezierpts[1] - bezierpts[0], " "bezierpts[2] - bezierpts[0]));"); // Drop curves that are nearly flat, in favor of the higher quality triangle antialiasing. g->codeAppendf("if (2 * abs(area_times_2) < length((bezierpts[2] - bezierpts[0]) * %s.zx)) {", rtAdjust); #ifndef SK_BUILD_FOR_MAC g->codeAppend ( "return;"); #else // Returning from this geometry shader makes Mac very unhappy. Instead we make wind 0. g->codeAppend ( "area_times_2 = 0;"); #endif g->codeAppend ("}"); g->codeAppendf("%s = sign(area_times_2);", outputWind); } void GrCCPRQuadraticProcessor::onEmitGeometryShader(GrGLSLGeometryBuilder* g, const char* emitVertexFn, const char* wind, const char* rtAdjust) const { // Prepend bezierpts at the start of the shader. g->codePrependf("highp float3x2 bezierpts = float3x2(sk_in[0].gl_Position.xy, " "sk_in[1].gl_Position.xy, " "sk_in[2].gl_Position.xy);"); g->declareGlobal(fCanonicalMatrix); g->codeAppendf("%s = float3x3(0.0, 0, 1, " "0.5, 0, 1, " "1.0, 1, 1) * " "inverse(float3x3(bezierpts[0], 1, " "bezierpts[1], 1, " "bezierpts[2], 1));", fCanonicalMatrix.c_str()); g->declareGlobal(fCanonicalDerivatives); g->codeAppendf("%s = float2x2(%s) * float2x2(%s.x, 0, 0, %s.z);", fCanonicalDerivatives.c_str(), fCanonicalMatrix.c_str(), rtAdjust, rtAdjust); g->declareGlobal(fEdgeDistanceEquation); g->codeAppendf("highp float2 edgept0 = bezierpts[%s > 0 ? 2 : 0];", wind); g->codeAppendf("highp float2 edgept1 = bezierpts[%s > 0 ? 0 : 2];", wind); this->emitEdgeDistanceEquation(g, "edgept0", "edgept1", fEdgeDistanceEquation.c_str()); this->emitQuadraticGeometry(g, emitVertexFn, rtAdjust); } void GrCCPRQuadraticProcessor::emitPerVertexGeometryCode(SkString* fnBody, const char* position, const char* /*coverage*/, const char* /*wind*/) const { fnBody->appendf("%s.xy = (%s * float3(%s, 1)).xy;", fXYD.gsOut(), fCanonicalMatrix.c_str(), position); fnBody->appendf("%s.z = dot(%s.xy, %s) + %s.z;", fXYD.gsOut(), fEdgeDistanceEquation.c_str(), position, fEdgeDistanceEquation.c_str()); this->onEmitPerVertexGeometryCode(fnBody); } void GrCCPRQuadraticHullProcessor::emitQuadraticGeometry(GrGLSLGeometryBuilder* g, const char* emitVertexFn, const char* /*rtAdjust*/) const { // Find the t value whose tangent is halfway between the tangents at the endpionts. // (We defined bezierpts in onEmitGeometryShader.) g->codeAppend ("highp float2 tan0 = bezierpts[1] - bezierpts[0];"); g->codeAppend ("highp float2 tan1 = bezierpts[2] - bezierpts[1];"); g->codeAppend ("highp float2 midnorm = normalize(tan0) - normalize(tan1);"); g->codeAppend ("highp float2 T = midnorm * float2x2(tan0 - tan1, tan0);"); g->codeAppend ("highp float t = clamp(T.t / T.s, 0, 1);"); // T.s=0 is weeded out by this point. // Clip the bezier triangle by the tangent at our new t value. This is a simple application for // De Casteljau's algorithm. g->codeAppendf("highp float4x2 quadratic_hull = float4x2(bezierpts[0], " "bezierpts[0] + tan0 * t, " "bezierpts[1] + tan1 * t, " "bezierpts[2]);"); int maxVerts = this->emitHullGeometry(g, emitVertexFn, "quadratic_hull", 4, "sk_InvocationID"); g->configure(GrGLSLGeometryBuilder::InputType::kTriangles, GrGLSLGeometryBuilder::OutputType::kTriangleStrip, maxVerts, 4); } void GrCCPRQuadraticHullProcessor::onEmitPerVertexGeometryCode(SkString* fnBody) const { fnBody->appendf("%s = float2(2 * %s.x, -1) * %s;", fGradXY.gsOut(), fXYD.gsOut(), fCanonicalDerivatives.c_str()); } void GrCCPRQuadraticHullProcessor::emitShaderCoverage(GrGLSLFragmentBuilder* f, const char* outputCoverage) const { f->codeAppendf("highp float d = (%s.x * %s.x - %s.y) * inversesqrt(dot(%s, %s));", fXYD.fsIn(), fXYD.fsIn(), fXYD.fsIn(), fGradXY.fsIn(), fGradXY.fsIn()); f->codeAppendf("%s = clamp(0.5 - d, 0, 1);", outputCoverage); f->codeAppendf("%s += min(%s.z, 0);", outputCoverage, fXYD.fsIn()); // Flat closing edge. } void GrCCPRQuadraticCornerProcessor::emitQuadraticGeometry(GrGLSLGeometryBuilder* g, const char* emitVertexFn, const char* rtAdjust) const { g->declareGlobal(fEdgeDistanceDerivatives); g->codeAppendf("%s = %s.xy * %s.xz;", fEdgeDistanceDerivatives.c_str(), fEdgeDistanceEquation.c_str(), rtAdjust); g->codeAppendf("highp float2 corner = bezierpts[sk_InvocationID * 2];"); int numVertices = this->emitCornerGeometry(g, emitVertexFn, "corner"); g->configure(GrGLSLGeometryBuilder::InputType::kTriangles, GrGLSLGeometryBuilder::OutputType::kTriangleStrip, numVertices, 2); } void GrCCPRQuadraticCornerProcessor::onEmitPerVertexGeometryCode(SkString* fnBody) const { fnBody->appendf("%s = float3(%s[0].x, %s[0].y, %s.x);", fdXYDdx.gsOut(), fCanonicalDerivatives.c_str(), fCanonicalDerivatives.c_str(), fEdgeDistanceDerivatives.c_str()); fnBody->appendf("%s = float3(%s[1].x, %s[1].y, %s.y);", fdXYDdy.gsOut(), fCanonicalDerivatives.c_str(), fCanonicalDerivatives.c_str(), fEdgeDistanceDerivatives.c_str()); } void GrCCPRQuadraticCornerProcessor::emitShaderCoverage(GrGLSLFragmentBuilder* f, const char* outputCoverage) const { f->codeAppendf("highp float x = %s.x, y = %s.y, d = %s.z;", fXYD.fsIn(), fXYD.fsIn(), fXYD.fsIn()); f->codeAppendf("highp float2x3 grad_xyd = float2x3(%s, %s);", fdXYDdx.fsIn(), fdXYDdy.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->codeAppend ("highp float f = x*x - y;"); f->codeAppend ("highp float2 grad_f = float2(2*x, -1) * float2x2(grad_xyd);"); f->codeAppendf("%s = -(0.5 - f * inversesqrt(dot(grad_f, grad_f)));", outputCoverage); f->codeAppendf("%s -= d;", outputCoverage); // Use software msaa to approximate coverage at the corner pixels. int sampleCount = this->defineSoftSampleLocations(f, "samples"); f->codeAppendf("highp float3 xyd_center = float3(%s.xy, %s.z + 0.5);", fXYD.fsIn(), fXYD.fsIn()); f->codeAppendf("for (int i = 0; i < %i; ++i) {", sampleCount); f->codeAppend ( "highp float3 xyd = grad_xyd * samples[i] + xyd_center;"); f->codeAppend ( "lowp float f = xyd.y - xyd.x * xyd.x;"); // f > 0 -> inside curve. f->codeAppendf( "%s += all(greaterThan(float2(f,xyd.z), float2(0))) ? %f : 0;", outputCoverage, 1.0 / sampleCount); f->codeAppendf("}"); }