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- /*
- * 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 "src/gpu/ccpr/GrCCCoverageProcessor.h"
- #include "src/core/SkMakeUnique.h"
- #include "src/gpu/GrGpuCommandBuffer.h"
- #include "src/gpu/GrOpFlushState.h"
- #include "src/gpu/ccpr/GrCCConicShader.h"
- #include "src/gpu/ccpr/GrCCCubicShader.h"
- #include "src/gpu/ccpr/GrCCQuadraticShader.h"
- #include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
- #include "src/gpu/glsl/GrGLSLVertexGeoBuilder.h"
- #include "src/gpu/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,
- const char* /*wind*/) 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 emitFragmentCoverageCode(
- 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());
- }
- }
- void emitSampleMaskCode(GrGLSLFPFragmentBuilder*) const override { return; }
- 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(half(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(half(area_x2));", outputWind);
- }
- }
- 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 = half(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] = half(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
- //
- // NOTE: leftDir and rightDir are normalized and point in the same direction the path was
- // defined with, i.e., leftDir points into the corner and rightDir points away from the corner.
- s->codeAppendf("half obtuseness = max(half(dot(%s, %s)), 0);", leftDir, rightDir);
- // axis_alignedness = 1 - tan(angle_to_nearest_axis_from_corner_bisector)
- // (i.e., 1 when the corner bisector is aligned with the x- or y-axis
- // 0 when the corner bisector falls on a 45 degree angle
- // 0..1 when the corner bisector falls somewhere in between
- s->codeAppendf("half2 abs_bisect_maybe_transpose = abs((0 == obtuseness) ? half2(%s - %s) : "
- "half2(%s + %s));",
- leftDir, rightDir, leftDir, rightDir);
- s->codeAppend ("half axis_alignedness = "
- "1 - min(abs_bisect_maybe_transpose.y, abs_bisect_maybe_transpose.x) / "
- "max(abs_bisect_maybe_transpose.x, abs_bisect_maybe_transpose.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);
- }
- 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 this->onCreateGLSLInstance(std::move(shader));
- }
- 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);
- }
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