| /* | |
| * 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 "GrCCCoverageProcessor.h" | |
| #include "GrGpuCommandBuffer.h" | |
| #include "GrOpFlushState.h" | |
| #include "SkMakeUnique.h" | |
| #include "ccpr/GrCCConicShader.h" | |
| #include "ccpr/GrCCCubicShader.h" | |
| #include "ccpr/GrCCQuadraticShader.h" | |
| #include "glsl/GrGLSLVertexGeoBuilder.h" | |
| #include "glsl/GrGLSLFragmentShaderBuilder.h" | |
| #include "glsl/GrGLSLVertexGeoBuilder.h" | |
| class GrCCCoverageProcessor::TriangleShader : public GrCCCoverageProcessor::Shader { | |
| void onEmitVaryings(GrGLSLVaryingHandler* varyingHandler, GrGLSLVarying::Scope scope, | |
| SkString* code, const char* position, const char* coverage, | |
| const char* cornerCoverage) override { | |
| if (!cornerCoverage) { | |
| fCoverages.reset(kHalf_GrSLType, scope); | |
| varyingHandler->addVarying("coverage", &fCoverages); | |
| code->appendf("%s = %s;", OutName(fCoverages), coverage); | |
| } else { | |
| fCoverages.reset(kHalf3_GrSLType, scope); | |
| varyingHandler->addVarying("coverages", &fCoverages); | |
| code->appendf("%s = half3(%s, %s);", OutName(fCoverages), coverage, cornerCoverage); | |
| } | |
| } | |
| void onEmitFragmentCode(GrGLSLFPFragmentBuilder* f, const char* outputCoverage) const override { | |
| if (kHalf_GrSLType == fCoverages.type()) { | |
| f->codeAppendf("%s = %s;", outputCoverage, fCoverages.fsIn()); | |
| } else { | |
| f->codeAppendf("%s = %s.z * %s.y + %s.x;", | |
| outputCoverage, fCoverages.fsIn(), fCoverages.fsIn(), fCoverages.fsIn()); | |
| } | |
| } | |
| GrGLSLVarying fCoverages; | |
| }; | |
| void GrCCCoverageProcessor::Shader::CalcWind(const GrCCCoverageProcessor& proc, | |
| GrGLSLVertexGeoBuilder* s, const char* pts, | |
| const char* outputWind) { | |
| if (3 == proc.numInputPoints()) { | |
| s->codeAppendf("float2 a = %s[0] - %s[1], " | |
| "b = %s[0] - %s[2];", pts, pts, pts, pts); | |
| } else { | |
| // All inputs are convex, so it's sufficient to just average the middle two input points. | |
| SkASSERT(4 == proc.numInputPoints()); | |
| s->codeAppendf("float2 p12 = (%s[1] + %s[2]) * .5;", pts, pts); | |
| s->codeAppendf("float2 a = %s[0] - p12, " | |
| "b = %s[0] - %s[3];", pts, pts, pts); | |
| } | |
| s->codeAppend ("float area_x2 = determinant(float2x2(a, b));"); | |
| if (proc.isTriangles()) { | |
| // We cull extremely thin triangles by zeroing wind. When a triangle gets too thin it's | |
| // possible for FP round-off error to actually give us the wrong winding direction, causing | |
| // rendering artifacts. The criteria we choose is "height <~ 1/1024". So we drop a triangle | |
| // if the max effect it can have on any single pixel is <~ 1/1024, or 1/4 of a bit in 8888. | |
| s->codeAppend ("float2 bbox_size = max(abs(a), abs(b));"); | |
| s->codeAppend ("float basewidth = max(bbox_size.x + bbox_size.y, 1);"); | |
| s->codeAppendf("%s = (abs(area_x2 * 1024) > basewidth) ? sign(area_x2) : 0;", outputWind); | |
| } else { | |
| // We already converted nearly-flat curves to lines on the CPU, so no need to worry about | |
| // thin curve hulls at this point. | |
| s->codeAppendf("%s = sign(area_x2);", outputWind); | |
| } | |
| } | |
| void GrCCCoverageProcessor::Shader::EmitEdgeDistanceEquation(GrGLSLVertexGeoBuilder* s, | |
| const char* leftPt, | |
| const char* rightPt, | |
| const char* outputDistanceEquation) { | |
| s->codeAppendf("float2 n = float2(%s.y - %s.y, %s.x - %s.x);", | |
| rightPt, leftPt, leftPt, rightPt); | |
| s->codeAppend ("float nwidth = (abs(n.x) + abs(n.y)) * (bloat * 2);"); | |
| // When nwidth=0, wind must also be 0 (and coverage * wind = 0). So it doesn't matter what we | |
| // come up with here as long as it isn't NaN or Inf. | |
| s->codeAppend ("n /= (0 != nwidth) ? nwidth : 1;"); | |
| s->codeAppendf("%s = float3(-n, dot(n, %s) - .5);", outputDistanceEquation, leftPt); | |
| } | |
| void GrCCCoverageProcessor::Shader::CalcEdgeCoverageAtBloatVertex(GrGLSLVertexGeoBuilder* s, | |
| const char* leftPt, | |
| const char* rightPt, | |
| const char* rasterVertexDir, | |
| const char* outputCoverage) { | |
| // Here we find an edge's coverage at one corner of a conservative raster bloat box whose center | |
| // falls on the edge in question. (A bloat box is axis-aligned and the size of one pixel.) We | |
| // always set up coverage so it is -1 at the outermost corner, 0 at the innermost, and -.5 at | |
| // the center. Interpolated, these coverage values convert jagged conservative raster edges into | |
| // smooth antialiased edges. | |
| // | |
| // d1 == (P + sign(n) * bloat) dot n (Distance at the bloat box vertex whose | |
| // == P dot n + (abs(n.x) + abs(n.y)) * bloatSize coverage=-1, where the bloat box is | |
| // centered on P.) | |
| // | |
| // d0 == (P - sign(n) * bloat) dot n (Distance at the bloat box vertex whose | |
| // == P dot n - (abs(n.x) + abs(n.y)) * bloatSize coverage=0, where the bloat box is | |
| // centered on P.) | |
| // | |
| // d == (P + rasterVertexDir * bloatSize) dot n (Distance at the bloat box vertex whose | |
| // == P dot n + (rasterVertexDir dot n) * bloatSize coverage we wish to calculate.) | |
| // | |
| // coverage == -(d - d0) / (d1 - d0) (coverage=-1 at d=d1; coverage=0 at d=d0) | |
| // | |
| // == (rasterVertexDir dot n) / (abs(n.x) + abs(n.y)) * -.5 - .5 | |
| // | |
| s->codeAppendf("float2 n = float2(%s.y - %s.y, %s.x - %s.x);", | |
| rightPt, leftPt, leftPt, rightPt); | |
| s->codeAppend ("float nwidth = abs(n.x) + abs(n.y);"); | |
| s->codeAppendf("float t = dot(%s, n);", rasterVertexDir); | |
| // The below conditional guarantees we get exactly 1 on the divide when nwidth=t (in case the | |
| // GPU divides by multiplying by the reciprocal?) It also guards against NaN when nwidth=0. | |
| s->codeAppendf("%s = (abs(t) != nwidth ? t / nwidth : sign(t)) * -.5 - .5;", outputCoverage); | |
| } | |
| void GrCCCoverageProcessor::Shader::CalcEdgeCoveragesAtBloatVertices(GrGLSLVertexGeoBuilder* s, | |
| const char* leftPt, | |
| const char* rightPt, | |
| const char* bloatDir1, | |
| const char* bloatDir2, | |
| const char* outputCoverages) { | |
| // See comments in CalcEdgeCoverageAtBloatVertex. | |
| s->codeAppendf("float2 n = float2(%s.y - %s.y, %s.x - %s.x);", | |
| rightPt, leftPt, leftPt, rightPt); | |
| s->codeAppend ("float nwidth = abs(n.x) + abs(n.y);"); | |
| s->codeAppendf("float2 t = n * float2x2(%s, %s);", bloatDir1, bloatDir2); | |
| s->codeAppendf("for (int i = 0; i < 2; ++i) {"); | |
| s->codeAppendf( "%s[i] = (abs(t[i]) != nwidth ? t[i] / nwidth : sign(t[i])) * -.5 - .5;", | |
| outputCoverages); | |
| s->codeAppendf("}"); | |
| } | |
| void GrCCCoverageProcessor::Shader::CalcCornerAttenuation(GrGLSLVertexGeoBuilder* s, | |
| const char* leftDir, const char* rightDir, | |
| const char* outputAttenuation) { | |
| // obtuseness = cos(corner_angle) if corner_angle > 90 degrees | |
| // 0 if corner_angle <= 90 degrees | |
| s->codeAppendf("half obtuseness = max(dot(%s, %s), 0);", leftDir, rightDir); | |
| // axis_alignedness = 1 when the leftDir/rightDir bisector is aligned with the x- or y-axis | |
| // 0 when the bisector falls on a 45 degree angle | |
| // (i.e. 1 - tan(angle_to_nearest_axis)) | |
| s->codeAppendf("half2 abs_bisect = abs(%s - %s);", leftDir, rightDir); | |
| s->codeAppend ("half axis_alignedness = 1 - min(abs_bisect.y, abs_bisect.x) / " | |
| "max(abs_bisect.x, abs_bisect.y);"); | |
| // ninety_degreesness = sin^2(corner_angle) | |
| // sin^2 just because... it's always positive and the results looked better than plain sine... ? | |
| s->codeAppendf("half ninety_degreesness = determinant(half2x2(%s, %s));", leftDir, rightDir); | |
| s->codeAppend ("ninety_degreesness = ninety_degreesness * ninety_degreesness;"); | |
| // The below formula is not smart. It was just arrived at by considering the following | |
| // observations: | |
| // | |
| // 1. 90-degree, axis-aligned corners have full attenuation along the bisector. | |
| // (i.e. coverage = 1 - distance_to_corner^2) | |
| // (i.e. outputAttenuation = 0) | |
| // | |
| // 2. 180-degree corners always have zero attenuation. | |
| // (i.e. coverage = 1 - distance_to_corner) | |
| // (i.e. outputAttenuation = 1) | |
| // | |
| // 3. 90-degree corners whose bisector falls on a 45 degree angle also do not attenuate. | |
| // (i.e. outputAttenuation = 1) | |
| s->codeAppendf("%s = max(obtuseness, axis_alignedness * ninety_degreesness);", | |
| outputAttenuation); | |
| } | |
| void GrCCCoverageProcessor::getGLSLProcessorKey(const GrShaderCaps&, | |
| GrProcessorKeyBuilder* b) const { | |
| int key = (int)fPrimitiveType << 2; | |
| if (GSSubpass::kCorners == fGSSubpass) { | |
| key |= 2; | |
| } | |
| if (Impl::kVertexShader == fImpl) { | |
| key |= 1; | |
| } | |
| #ifdef SK_DEBUG | |
| uint32_t bloatBits; | |
| memcpy(&bloatBits, &fDebugBloat, 4); | |
| b->add32(bloatBits); | |
| #endif | |
| b->add32(key); | |
| } | |
| GrGLSLPrimitiveProcessor* GrCCCoverageProcessor::createGLSLInstance(const GrShaderCaps&) const { | |
| std::unique_ptr<Shader> shader; | |
| switch (fPrimitiveType) { | |
| case PrimitiveType::kTriangles: | |
| case PrimitiveType::kWeightedTriangles: | |
| shader = skstd::make_unique<TriangleShader>(); | |
| break; | |
| case PrimitiveType::kQuadratics: | |
| shader = skstd::make_unique<GrCCQuadraticShader>(); | |
| break; | |
| case PrimitiveType::kCubics: | |
| shader = skstd::make_unique<GrCCCubicShader>(); | |
| break; | |
| case PrimitiveType::kConics: | |
| shader = skstd::make_unique<GrCCConicShader>(); | |
| break; | |
| } | |
| return Impl::kGeometryShader == fImpl ? this->createGSImpl(std::move(shader)) | |
| : this->createVSImpl(std::move(shader)); | |
| } | |
| void GrCCCoverageProcessor::Shader::emitFragmentCode(const GrCCCoverageProcessor& proc, | |
| GrGLSLFPFragmentBuilder* f, | |
| const char* skOutputColor, | |
| const char* skOutputCoverage) const { | |
| f->codeAppendf("half coverage = 0;"); | |
| this->onEmitFragmentCode(f, "coverage"); | |
| f->codeAppendf("%s.a = coverage;", skOutputColor); | |
| f->codeAppendf("%s = half4(1);", skOutputCoverage); | |
| } | |
| void GrCCCoverageProcessor::draw(GrOpFlushState* flushState, const GrPipeline& pipeline, | |
| const SkIRect scissorRects[], const GrMesh meshes[], int meshCount, | |
| const SkRect& drawBounds) const { | |
| GrPipeline::DynamicStateArrays dynamicStateArrays; | |
| dynamicStateArrays.fScissorRects = scissorRects; | |
| GrGpuRTCommandBuffer* cmdBuff = flushState->rtCommandBuffer(); | |
| cmdBuff->draw(*this, pipeline, nullptr, &dynamicStateArrays, meshes, meshCount, drawBounds); | |
| // Geometry shader backend draws primitives in two subpasses. | |
| if (Impl::kGeometryShader == fImpl) { | |
| SkASSERT(GSSubpass::kHulls == fGSSubpass); | |
| GrCCCoverageProcessor cornerProc(*this, GSSubpass::kCorners); | |
| cmdBuff->draw(cornerProc, pipeline, nullptr, &dynamicStateArrays, meshes, meshCount, | |
| drawBounds); | |
| } | |
| } |