Split GrCCCoverageProcessor into subclasses
Makes separate subclasses for geometry and vertex shaders.
Bug: skia:
Change-Id: Ifced79af3092090a71d03fe252fb4da76738cf08
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/204545
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/ccpr/GrGSCoverageProcessor.cpp b/src/gpu/ccpr/GrGSCoverageProcessor.cpp
new file mode 100644
index 0000000..2a3acc3
--- /dev/null
+++ b/src/gpu/ccpr/GrGSCoverageProcessor.cpp
@@ -0,0 +1,430 @@
+/*
+ * 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 "GrGSCoverageProcessor.h"
+
+#include "GrMesh.h"
+#include "glsl/GrGLSLVertexGeoBuilder.h"
+
+using InputType = GrGLSLGeometryBuilder::InputType;
+using OutputType = GrGLSLGeometryBuilder::OutputType;
+
+/**
+ * This class and its subclasses implement the coverage processor with geometry shaders.
+ */
+class GrGSCoverageProcessor::Impl : public GrGLSLGeometryProcessor {
+protected:
+ Impl(std::unique_ptr<Shader> shader) : fShader(std::move(shader)) {}
+
+ virtual bool hasCoverage() const { return false; }
+
+ void setData(const GrGLSLProgramDataManager& pdman, const GrPrimitiveProcessor&,
+ FPCoordTransformIter&& transformIter) final {
+ this->setTransformDataHelper(SkMatrix::I(), pdman, &transformIter);
+ }
+
+ void onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) final {
+ const GrGSCoverageProcessor& proc = args.fGP.cast<GrGSCoverageProcessor>();
+
+ // The vertex shader simply forwards transposed x or y values to the geometry shader.
+ SkASSERT(1 == proc.numVertexAttributes());
+ gpArgs->fPositionVar = proc.fInputXOrYValues.asShaderVar();
+
+ // Geometry shader.
+ GrGLSLVaryingHandler* varyingHandler = args.fVaryingHandler;
+ this->emitGeometryShader(proc, varyingHandler, args.fGeomBuilder, args.fRTAdjustName);
+ varyingHandler->emitAttributes(proc);
+ varyingHandler->setNoPerspective();
+ SkASSERT(!args.fFPCoordTransformHandler->nextCoordTransform());
+
+ // Fragment shader.
+ fShader->emitFragmentCode(proc, args.fFragBuilder, args.fOutputColor, args.fOutputCoverage);
+ }
+
+ void emitGeometryShader(
+ const GrGSCoverageProcessor& proc, GrGLSLVaryingHandler* varyingHandler,
+ GrGLSLGeometryBuilder* g, const char* rtAdjust) const {
+ int numInputPoints = proc.numInputPoints();
+ SkASSERT(3 == numInputPoints || 4 == numInputPoints);
+
+ int inputWidth = (4 == numInputPoints || proc.hasInputWeight()) ? 4 : 3;
+ const char* posValues = (4 == inputWidth) ? "sk_Position" : "sk_Position.xyz";
+ g->codeAppendf("float%ix2 pts = transpose(float2x%i(sk_in[0].%s, sk_in[1].%s));",
+ inputWidth, inputWidth, posValues, posValues);
+
+ GrShaderVar wind("wind", kHalf_GrSLType);
+ g->declareGlobal(wind);
+ Shader::CalcWind(proc, g, "pts", wind.c_str());
+ if (PrimitiveType::kWeightedTriangles == proc.primitiveType()) {
+ SkASSERT(3 == numInputPoints);
+ SkASSERT(kFloat4_GrVertexAttribType == proc.fInputXOrYValues.cpuType());
+ g->codeAppendf("%s *= half(sk_in[0].sk_Position.w);", wind.c_str());
+ }
+
+ SkString emitVertexFn;
+ SkSTArray<2, GrShaderVar> emitArgs;
+ const char* corner = emitArgs.emplace_back("corner", kFloat2_GrSLType).c_str();
+ const char* bloatdir = emitArgs.emplace_back("bloatdir", kFloat2_GrSLType).c_str();
+ const char* coverage = nullptr;
+ if (this->hasCoverage()) {
+ coverage = emitArgs.emplace_back("coverage", kHalf_GrSLType).c_str();
+ }
+ const char* cornerCoverage = nullptr;
+ if (Subpass::kCorners == proc.fSubpass) {
+ cornerCoverage = emitArgs.emplace_back("corner_coverage", kHalf2_GrSLType).c_str();
+ }
+ g->emitFunction(kVoid_GrSLType, "emitVertex", emitArgs.count(), emitArgs.begin(), [&]() {
+ SkString fnBody;
+ if (coverage) {
+ fnBody.appendf("%s *= %s;", coverage, wind.c_str());
+ }
+ if (cornerCoverage) {
+ fnBody.appendf("%s.x *= %s;", cornerCoverage, wind.c_str());
+ }
+ fnBody.appendf("float2 vertexpos = fma(%s, float2(bloat), %s);", bloatdir, corner);
+ fShader->emitVaryings(varyingHandler, GrGLSLVarying::Scope::kGeoToFrag, &fnBody,
+ "vertexpos", coverage ? coverage : wind.c_str(), cornerCoverage);
+ g->emitVertex(&fnBody, "vertexpos", rtAdjust);
+ return fnBody;
+ }().c_str(), &emitVertexFn);
+
+ float bloat = kAABloatRadius;
+#ifdef SK_DEBUG
+ if (proc.debugBloatEnabled()) {
+ bloat *= proc.debugBloat();
+ }
+#endif
+ g->defineConstant("bloat", bloat);
+
+ this->onEmitGeometryShader(proc, g, wind, emitVertexFn.c_str());
+ }
+
+ virtual void onEmitGeometryShader(const GrGSCoverageProcessor&, GrGLSLGeometryBuilder*,
+ const GrShaderVar& wind, const char* emitVertexFn) const = 0;
+
+ const std::unique_ptr<Shader> fShader;
+
+ typedef GrGLSLGeometryProcessor INHERITED;
+};
+
+/**
+ * Generates conservative rasters around a triangle and its edges, and calculates coverage ramps.
+ *
+ * Triangle rough outlines are drawn in two steps: (1) draw a conservative raster of the entire
+ * triangle, with a coverage of +1, and (2) draw conservative rasters around each edge, with a
+ * coverage ramp from -1 to 0. These edge coverage values convert jagged conservative raster edges
+ * into smooth, antialiased ones.
+ *
+ * The final corners get touched up in a later step by TriangleCornerImpl.
+ */
+class GrGSCoverageProcessor::TriangleHullImpl : public GrGSCoverageProcessor::Impl {
+public:
+ TriangleHullImpl(std::unique_ptr<Shader> shader) : Impl(std::move(shader)) {}
+
+ bool hasCoverage() const override { return true; }
+
+ void onEmitGeometryShader(const GrGSCoverageProcessor&, GrGLSLGeometryBuilder* g,
+ const GrShaderVar& wind, const char* emitVertexFn) const override {
+ fShader->emitSetupCode(g, "pts", wind.c_str());
+
+ // Visualize the input triangle as upright and equilateral, with a flat base. Paying special
+ // attention to wind, we can identify the points as top, bottom-left, and bottom-right.
+ //
+ // NOTE: We generate the rasters in 5 independent invocations, so each invocation designates
+ // the corner it will begin with as the top.
+ g->codeAppendf("int i = (%s > 0 ? sk_InvocationID : 4 - sk_InvocationID) %% 3;",
+ wind.c_str());
+ g->codeAppend ("float2 top = pts[i];");
+ g->codeAppendf("float2 right = pts[(i + (%s > 0 ? 1 : 2)) %% 3];", wind.c_str());
+ g->codeAppendf("float2 left = pts[(i + (%s > 0 ? 2 : 1)) %% 3];", wind.c_str());
+
+ // Determine which direction to outset the conservative raster from each of the three edges.
+ g->codeAppend ("float2 leftbloat = sign(top - left);");
+ g->codeAppend ("leftbloat = float2(0 != leftbloat.y ? leftbloat.y : leftbloat.x, "
+ "0 != leftbloat.x ? -leftbloat.x : -leftbloat.y);");
+
+ g->codeAppend ("float2 rightbloat = sign(right - top);");
+ g->codeAppend ("rightbloat = float2(0 != rightbloat.y ? rightbloat.y : rightbloat.x, "
+ "0 != rightbloat.x ? -rightbloat.x : -rightbloat.y);");
+
+ g->codeAppend ("float2 downbloat = sign(left - right);");
+ g->codeAppend ("downbloat = float2(0 != downbloat.y ? downbloat.y : downbloat.x, "
+ "0 != downbloat.x ? -downbloat.x : -downbloat.y);");
+
+ // The triangle's conservative raster has a coverage of +1 all around.
+ g->codeAppend ("half4 coverages = half4(+1);");
+
+ // Edges have coverage ramps.
+ g->codeAppend ("if (sk_InvocationID >= 2) {"); // Are we an edge?
+ Shader::CalcEdgeCoverageAtBloatVertex(g, "top", "right",
+ "float2(+rightbloat.y, -rightbloat.x)",
+ "coverages[0]");
+ g->codeAppend ( "coverages.yzw = half3(-1, 0, -1 - coverages[0]);");
+ // Reassign bloats to characterize a conservative raster around a single edge, rather than
+ // the entire triangle.
+ g->codeAppend ( "leftbloat = downbloat = -rightbloat;");
+ g->codeAppend ("}");
+
+ // Here we generate the conservative raster geometry. The triangle's conservative raster is
+ // the convex hull of 3 pixel-size boxes centered on the input points. This translates to a
+ // convex polygon with either one, two, or three vertices at each input point (depending on
+ // how sharp the corner is) that we split between two invocations. Edge conservative rasters
+ // are convex hulls of 2 pixel-size boxes, one at each endpoint. For more details on
+ // conservative raster, see:
+ // https://developer.nvidia.com/gpugems/GPUGems2/gpugems2_chapter42.html
+ g->codeAppendf("bool2 left_right_notequal = notEqual(leftbloat, rightbloat);");
+ g->codeAppend ("if (all(left_right_notequal)) {");
+ // The top corner will have three conservative raster vertices. Emit the
+ // middle one first to the triangle strip.
+ g->codeAppendf( "%s(top, float2(-leftbloat.y, +leftbloat.x), coverages[0]);",
+ emitVertexFn);
+ g->codeAppend ("}");
+ g->codeAppend ("if (any(left_right_notequal)) {");
+ // Second conservative raster vertex for the top corner.
+ g->codeAppendf( "%s(top, rightbloat, coverages[1]);", emitVertexFn);
+ g->codeAppend ("}");
+
+ // Main interior body.
+ g->codeAppendf("%s(top, leftbloat, coverages[2]);", emitVertexFn);
+ g->codeAppendf("%s(right, rightbloat, coverages[1]);", emitVertexFn);
+
+ // Here the invocations diverge slightly. We can't symmetrically divide three triangle
+ // points between two invocations, so each does the following:
+ //
+ // sk_InvocationID=0: Finishes the main interior body of the triangle hull.
+ // sk_InvocationID=1: Remaining two conservative raster vertices for the third hull corner.
+ // sk_InvocationID=2..4: Finish the opposite endpoint of their corresponding edge.
+ g->codeAppendf("bool2 right_down_notequal = notEqual(rightbloat, downbloat);");
+ g->codeAppend ("if (any(right_down_notequal) || 0 == sk_InvocationID) {");
+ g->codeAppendf( "%s((0 == sk_InvocationID) ? left : right, "
+ "(0 == sk_InvocationID) ? leftbloat : downbloat, "
+ "coverages[2]);", emitVertexFn);
+ g->codeAppend ("}");
+ g->codeAppend ("if (all(right_down_notequal) && 0 != sk_InvocationID) {");
+ g->codeAppendf( "%s(right, float2(-rightbloat.y, +rightbloat.x), coverages[3]);",
+ emitVertexFn);
+ g->codeAppend ("}");
+
+ // 5 invocations: 2 triangle hull invocations and 3 edges.
+ g->configure(InputType::kLines, OutputType::kTriangleStrip, 6, 5);
+ }
+};
+
+/**
+ * Generates a conservative raster around a convex quadrilateral that encloses a cubic or quadratic.
+ */
+class GrGSCoverageProcessor::CurveHullImpl : public GrGSCoverageProcessor::Impl {
+public:
+ CurveHullImpl(std::unique_ptr<Shader> shader) : Impl(std::move(shader)) {}
+
+ void onEmitGeometryShader(const GrGSCoverageProcessor&, GrGLSLGeometryBuilder* g,
+ const GrShaderVar& wind, const char* emitVertexFn) const override {
+ const char* hullPts = "pts";
+ fShader->emitSetupCode(g, "pts", wind.c_str(), &hullPts);
+
+ // Visualize the input (convex) quadrilateral as a square. Paying special attention to wind,
+ // we can identify the points by their corresponding corner.
+ //
+ // NOTE: We split the square down the diagonal from top-right to bottom-left, and generate
+ // the hull in two independent invocations. Each invocation designates the corner it will
+ // begin with as top-left.
+ g->codeAppend ("int i = sk_InvocationID * 2;");
+ g->codeAppendf("float2 topleft = %s[i];", hullPts);
+ g->codeAppendf("float2 topright = %s[%s > 0 ? i + 1 : 3 - i];", hullPts, wind.c_str());
+ g->codeAppendf("float2 bottomleft = %s[%s > 0 ? 3 - i : i + 1];", hullPts, wind.c_str());
+ g->codeAppendf("float2 bottomright = %s[2 - i];", hullPts);
+
+ // Determine how much to outset the conservative raster hull from the relevant edges.
+ g->codeAppend ("float2 leftbloat = float2(topleft.y > bottomleft.y ? +1 : -1, "
+ "topleft.x > bottomleft.x ? -1 : +1);");
+ g->codeAppend ("float2 upbloat = float2(topright.y > topleft.y ? +1 : -1, "
+ "topright.x > topleft.x ? -1 : +1);");
+ g->codeAppend ("float2 rightbloat = float2(bottomright.y > topright.y ? +1 : -1, "
+ "bottomright.x > topright.x ? -1 : +1);");
+
+ // Here we generate the conservative raster geometry. It is the convex hull of 4 pixel-size
+ // boxes centered on the input points, split evenly between two invocations. This translates
+ // to a polygon with either one, two, or three vertices at each input point, depending on
+ // how sharp the corner is. For more details on conservative raster, see:
+ // https://developer.nvidia.com/gpugems/GPUGems2/gpugems2_chapter42.html
+ g->codeAppendf("bool2 left_up_notequal = notEqual(leftbloat, upbloat);");
+ g->codeAppend ("if (all(left_up_notequal)) {");
+ // The top-left corner will have three conservative raster vertices.
+ // Emit the middle one first to the triangle strip.
+ g->codeAppendf( "%s(topleft, float2(-leftbloat.y, leftbloat.x));", emitVertexFn);
+ g->codeAppend ("}");
+ g->codeAppend ("if (any(left_up_notequal)) {");
+ // Second conservative raster vertex for the top-left corner.
+ g->codeAppendf( "%s(topleft, leftbloat);", emitVertexFn);
+ g->codeAppend ("}");
+
+ // Main interior body of this invocation's half of the hull.
+ g->codeAppendf("%s(topleft, upbloat);", emitVertexFn);
+ g->codeAppendf("%s(bottomleft, leftbloat);", emitVertexFn);
+ g->codeAppendf("%s(topright, upbloat);", emitVertexFn);
+
+ // Remaining two conservative raster vertices for the top-right corner.
+ g->codeAppendf("bool2 up_right_notequal = notEqual(upbloat, rightbloat);");
+ g->codeAppend ("if (any(up_right_notequal)) {");
+ g->codeAppendf( "%s(topright, rightbloat);", emitVertexFn);
+ g->codeAppend ("}");
+ g->codeAppend ("if (all(up_right_notequal)) {");
+ g->codeAppendf( "%s(topright, float2(-upbloat.y, upbloat.x));", emitVertexFn);
+ g->codeAppend ("}");
+
+ g->configure(InputType::kLines, OutputType::kTriangleStrip, 7, 2);
+ }
+};
+
+/**
+ * Generates conservative rasters around corners (aka pixel-size boxes) and calculates
+ * coverage and attenuation ramps to fix up the coverage values written by the hulls.
+ */
+class GrGSCoverageProcessor::CornerImpl : public GrGSCoverageProcessor::Impl {
+public:
+ CornerImpl(std::unique_ptr<Shader> shader) : Impl(std::move(shader)) {}
+
+ bool hasCoverage() const override { return true; }
+
+ void onEmitGeometryShader(const GrGSCoverageProcessor& proc, GrGLSLGeometryBuilder* g,
+ const GrShaderVar& wind, const char* emitVertexFn) const override {
+ fShader->emitSetupCode(g, "pts", wind.c_str());
+
+ g->codeAppendf("int corneridx = sk_InvocationID;");
+ if (!proc.isTriangles()) {
+ g->codeAppendf("corneridx *= %i;", proc.numInputPoints() - 1);
+ }
+
+ g->codeAppendf("float2 corner = pts[corneridx];");
+ g->codeAppendf("float2 left = pts[(corneridx + (%s > 0 ? %i : 1)) %% %i];",
+ wind.c_str(), proc.numInputPoints() - 1, proc.numInputPoints());
+ g->codeAppendf("float2 right = pts[(corneridx + (%s > 0 ? 1 : %i)) %% %i];",
+ wind.c_str(), proc.numInputPoints() - 1, proc.numInputPoints());
+
+ g->codeAppend ("float2 leftdir = corner - left;");
+ g->codeAppend ("leftdir = (float2(0) != leftdir) ? normalize(leftdir) : float2(1, 0);");
+
+ g->codeAppend ("float2 rightdir = right - corner;");
+ g->codeAppend ("rightdir = (float2(0) != rightdir) ? normalize(rightdir) : float2(1, 0);");
+
+ // Find "outbloat" and "crossbloat" at our corner. The outbloat points diagonally out of the
+ // triangle, in the direction that should ramp to zero coverage with attenuation. The
+ // crossbloat runs perpindicular to outbloat.
+ g->codeAppend ("float2 outbloat = float2(leftdir.x > rightdir.x ? +1 : -1, "
+ "leftdir.y > rightdir.y ? +1 : -1);");
+ g->codeAppend ("float2 crossbloat = float2(-outbloat.y, +outbloat.x);");
+
+ g->codeAppend ("half attenuation; {");
+ Shader::CalcCornerAttenuation(g, "leftdir", "rightdir", "attenuation");
+ g->codeAppend ("}");
+
+ if (proc.isTriangles()) {
+ g->codeAppend ("half2 left_coverages; {");
+ Shader::CalcEdgeCoveragesAtBloatVertices(g, "left", "corner", "-outbloat",
+ "-crossbloat", "left_coverages");
+ g->codeAppend ("}");
+
+ g->codeAppend ("half2 right_coverages; {");
+ Shader::CalcEdgeCoveragesAtBloatVertices(g, "corner", "right", "-outbloat",
+ "crossbloat", "right_coverages");
+ g->codeAppend ("}");
+
+ // Emit a corner box. The first coverage argument erases the values that were written
+ // previously by the hull and edge geometry. The second pair are multiplied together by
+ // the fragment shader. They ramp to 0 with attenuation in the direction of outbloat,
+ // and linearly from left-edge coverage to right-edge coverage in the direction of
+ // crossbloat.
+ //
+ // NOTE: Since this is not a linear mapping, it is important that the box's diagonal
+ // shared edge points in the direction of outbloat.
+ g->codeAppendf("%s(corner, -crossbloat, right_coverages[1] - left_coverages[1],"
+ "half2(1 + left_coverages[1], 1));",
+ emitVertexFn);
+
+ g->codeAppendf("%s(corner, outbloat, 1 + left_coverages[0] + right_coverages[0], "
+ "half2(0, attenuation));",
+ emitVertexFn);
+
+ g->codeAppendf("%s(corner, -outbloat, -1 - left_coverages[0] - right_coverages[0], "
+ "half2(1 + left_coverages[0] + right_coverages[0], 1));",
+ emitVertexFn);
+
+ g->codeAppendf("%s(corner, crossbloat, left_coverages[1] - right_coverages[1],"
+ "half2(1 + right_coverages[1], 1));",
+ emitVertexFn);
+ } else {
+ // Curves are simpler. The first coverage value of -1 means "wind = -wind", and causes
+ // the Shader to erase what it had written previously for the hull. Then, at each vertex
+ // of the corner box, the Shader will calculate the curve's local coverage value,
+ // interpolate it alongside our attenuation parameter, and multiply the two together for
+ // a final coverage value.
+ g->codeAppendf("%s(corner, -crossbloat, -1, half2(1));", emitVertexFn);
+ g->codeAppendf("%s(corner, outbloat, -1, half2(0, attenuation));",
+ emitVertexFn);
+ g->codeAppendf("%s(corner, -outbloat, -1, half2(1));", emitVertexFn);
+ g->codeAppendf("%s(corner, crossbloat, -1, half2(1));", emitVertexFn);
+ }
+
+ g->configure(InputType::kLines, OutputType::kTriangleStrip, 4, proc.isTriangles() ? 3 : 2);
+ }
+};
+
+void GrGSCoverageProcessor::reset(PrimitiveType primitiveType, GrResourceProvider*) {
+ fPrimitiveType = primitiveType; // This will affect the return values for numInputPoints, etc.
+
+ if (4 == this->numInputPoints() || this->hasInputWeight()) {
+ fInputXOrYValues =
+ {"x_or_y_values", kFloat4_GrVertexAttribType, kFloat4_GrSLType};
+ GR_STATIC_ASSERT(sizeof(QuadPointInstance) ==
+ 2 * GrVertexAttribTypeSize(kFloat4_GrVertexAttribType));
+ GR_STATIC_ASSERT(offsetof(QuadPointInstance, fY) ==
+ GrVertexAttribTypeSize(kFloat4_GrVertexAttribType));
+ } else {
+ fInputXOrYValues =
+ {"x_or_y_values", kFloat3_GrVertexAttribType, kFloat3_GrSLType};
+ GR_STATIC_ASSERT(sizeof(TriPointInstance) ==
+ 2 * GrVertexAttribTypeSize(kFloat3_GrVertexAttribType));
+ GR_STATIC_ASSERT(offsetof(TriPointInstance, fY) ==
+ GrVertexAttribTypeSize(kFloat3_GrVertexAttribType));
+ }
+
+ this->setVertexAttributes(&fInputXOrYValues, 1);
+}
+
+void GrGSCoverageProcessor::appendMesh(sk_sp<const GrGpuBuffer> instanceBuffer, int instanceCount,
+ int baseInstance, SkTArray<GrMesh>* out) const {
+ // We don't actually make instanced draw calls. Instead, we feed transposed x,y point values to
+ // the GPU in a regular vertex array and draw kLines (see initGS). Then, each vertex invocation
+ // receives either the shape's x or y values as inputs, which it forwards to the geometry
+ // shader.
+ GrMesh& mesh = out->emplace_back(GrPrimitiveType::kLines);
+ mesh.setNonIndexedNonInstanced(instanceCount * 2);
+ mesh.setVertexData(std::move(instanceBuffer), baseInstance * 2);
+}
+
+void GrGSCoverageProcessor::draw(
+ GrOpFlushState* flushState, const GrPipeline& pipeline, const SkIRect scissorRects[],
+ const GrMesh meshes[], int meshCount, const SkRect& drawBounds) const {
+ // The geometry shader impl draws primitives in two subpasses: The first pass fills the interior
+ // and does edge AA. The second pass does touch up on corner pixels.
+ for (int i = 0; i < 2; ++i) {
+ fSubpass = (Subpass) i;
+ this->GrCCCoverageProcessor::draw(
+ flushState, pipeline, scissorRects, meshes, meshCount, drawBounds);
+ }
+}
+
+GrGLSLPrimitiveProcessor* GrGSCoverageProcessor::onCreateGLSLInstance(
+ std::unique_ptr<Shader> shader) const {
+ if (Subpass::kHulls == fSubpass) {
+ return this->isTriangles()
+ ? (Impl*) new TriangleHullImpl(std::move(shader))
+ : (Impl*) new CurveHullImpl(std::move(shader));
+ }
+ SkASSERT(Subpass::kCorners == fSubpass);
+ return new CornerImpl(std::move(shader));
+}