CCPR: Rename GrCCPR* -> GrCC*
Also runs clang-format on the files that don't have special shader
builder styling.
Bug: skia:
Change-Id: I4a67569a7c8472acfb9200644c913844a92e3b2d
Reviewed-on: https://skia-review.googlesource.com/92083
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/src/gpu/ccpr/GrCCTriangleShader.cpp b/src/gpu/ccpr/GrCCTriangleShader.cpp
new file mode 100644
index 0000000..b507b37
--- /dev/null
+++ b/src/gpu/ccpr/GrCCTriangleShader.cpp
@@ -0,0 +1,152 @@
+/*
+ * 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 "GrCCTriangleShader.h"
+
+#include "glsl/GrGLSLFragmentShaderBuilder.h"
+#include "glsl/GrGLSLVertexGeoBuilder.h"
+
+using Shader = GrCCCoverageProcessor::Shader;
+
+Shader::WindHandling GrCCTriangleShader::onEmitVaryings(GrGLSLVaryingHandler* varyingHandler,
+ GrGLSLVarying::Scope scope,
+ SkString* code, const char* /*position*/,
+ const char* coverage, const char* wind) {
+ fCoverageTimesWind.reset(kHalf_GrSLType, scope);
+ if (!coverage) {
+ varyingHandler->addFlatVarying("wind", &fCoverageTimesWind);
+ code->appendf("%s = %s;", OutName(fCoverageTimesWind), wind);
+ } else {
+ varyingHandler->addVarying("coverage_times_wind", &fCoverageTimesWind);
+ code->appendf("%s = %s * %s;", OutName(fCoverageTimesWind), coverage, wind);
+ }
+ return WindHandling::kHandled;
+}
+
+void GrCCTriangleShader::onEmitFragmentCode(GrGLSLPPFragmentBuilder* f,
+ const char* outputCoverage) const {
+ f->codeAppendf("%s = %s;", outputCoverage, fCoverageTimesWind.fsIn());
+}
+
+void GrCCTriangleCornerShader::emitSetupCode(GrGLSLVertexGeoBuilder* s, const char* pts,
+ const char* repetitionID, const char* wind,
+ GeometryVars* vars) const {
+ s->codeAppendf("float2 corner = %s[%s];", pts, repetitionID);
+ vars->fCornerVars.fPoint = "corner";
+
+ s->codeAppendf("float2x2 vectors = float2x2(corner - %s[0 != %s ? %s - 1 : 2], "
+ "corner - %s[2 != %s ? %s + 1 : 0]);",
+ pts, repetitionID, repetitionID, pts, repetitionID,
+ repetitionID);
+
+ // Make sure neither vector is 0 to avoid a divide-by-zero. Wind will be zero anyway if this
+ // is the case, so whatever we output won't have any effect as long it isn't NaN or Inf.
+ s->codeAppend ("for (int i = 0; i < 2; ++i) {");
+ s->codeAppend ( "vectors[i] = (vectors[i] != float2(0)) ? vectors[i] : float2(1);");
+ s->codeAppend ("}");
+
+ // Find the vector that bisects the region outside the incoming edges. Each edge is
+ // responsible to subtract the outside region on its own the side of the bisector.
+ s->codeAppendf("float2 leftdir = normalize(vectors[%s > 0 ? 0 : 1]);", wind);
+ s->codeAppendf("float2 rightdir = normalize(vectors[%s > 0 ? 1 : 0]);", wind);
+ s->codeAppend ("float2 bisect = dot(leftdir, rightdir) >= 0 ? "
+ "leftdir + rightdir : "
+ "float2(leftdir.y - rightdir.y, rightdir.x - leftdir.x);");
+
+ // In ccpr we don't calculate exact geometric pixel coverage. What the distance-to-edge
+ // method actually finds is coverage inside a logical "AA box", one that is rotated inline
+ // with the edge, and in our case, up-scaled to circumscribe the actual pixel. Below we set
+ // up transformations into normalized logical AA box space for both incoming edges. These
+ // will tell the fragment shader where the corner is located within each edge's AA box.
+ s->declareGlobal(fAABoxMatrices);
+ s->declareGlobal(fAABoxTranslates);
+ s->declareGlobal(fGeoShaderBisects);
+ s->codeAppendf("for (int i = 0; i < 2; ++i) {");
+ // The X component runs parallel to the edge (i.e. distance to the corner).
+ s->codeAppendf( "float2 n = -vectors[%s > 0 ? i : 1 - i];", wind);
+ s->codeAppend ( "float nwidth = (abs(n.x) + abs(n.y)) * (bloat * 2);");
+ s->codeAppend ( "n /= nwidth;"); // nwidth != 0 because both vectors != 0.
+ s->codeAppendf( "%s[i][0] = n;", fAABoxMatrices.c_str());
+ s->codeAppendf( "%s[i][0] = -dot(n, corner) + .5;", fAABoxTranslates.c_str());
+
+ // The Y component runs perpendicular to the edge (i.e. distance-to-edge).
+ s->codeAppend ( "n = (i == 0) ? float2(-n.y, n.x) : float2(n.y, -n.x);");
+ s->codeAppendf( "%s[i][1] = n;", fAABoxMatrices.c_str());
+ s->codeAppendf( "%s[i][1] = -dot(n, corner) + .5;", fAABoxTranslates.c_str());
+
+ // Translate the bisector into logical AA box space.
+ // NOTE: Since the region outside two edges of a convex shape is in [180 deg, 360 deg], the
+ // bisector will therefore be in [90 deg, 180 deg]. Or, x >= 0 and y <= 0 in AA box space.
+ s->codeAppendf( "%s[i] = -bisect * %s[i];",
+ fGeoShaderBisects.c_str(), fAABoxMatrices.c_str());
+ s->codeAppend ("}");
+}
+
+Shader::WindHandling
+GrCCTriangleCornerShader::onEmitVaryings(GrGLSLVaryingHandler* varyingHandler,
+ GrGLSLVarying::Scope scope, SkString* code,
+ const char* position, const char* coverage,
+ const char* /*wind*/) {
+ SkASSERT(!coverage);
+
+ fCornerLocationInAABoxes.reset(kFloat2x2_GrSLType, scope);
+ varyingHandler->addVarying("corner_location_in_aa_boxes", &fCornerLocationInAABoxes);
+
+ fBisectInAABoxes.reset(kFloat2x2_GrSLType, scope);
+ varyingHandler->addFlatVarying("bisect_in_aa_boxes", &fBisectInAABoxes);
+
+ code->appendf("for (int i = 0; i < 2; ++i) {");
+ code->appendf( "%s[i] = %s * %s[i] + %s[i];",
+ OutName(fCornerLocationInAABoxes), position, fAABoxMatrices.c_str(),
+ fAABoxTranslates.c_str());
+ code->appendf( "%s[i] = %s[i];", OutName(fBisectInAABoxes), fGeoShaderBisects.c_str());
+ code->appendf("}");
+
+ return WindHandling::kNotHandled;
+}
+
+void GrCCTriangleCornerShader::onEmitFragmentCode(GrGLSLPPFragmentBuilder* f,
+ const char* outputCoverage) const {
+ // By the time we reach this shader, the pixel is in the following state:
+ //
+ // 1. The hull shader has emitted a coverage of 1.
+ // 2. Both edges have subtracted the area on their outside.
+ //
+ // This generally works, but it is a problem for corner pixels. There is a region within
+ // corner pixels that is outside both edges at the same time. This means the region has been
+ // double subtracted (once by each edge). The purpose of this shader is to fix these corner
+ // pixels.
+ //
+ // More specifically, each edge redoes its coverage analysis so that it only subtracts the
+ // outside area that falls on its own side of the bisector line.
+ //
+ // NOTE: unless the edges fall on multiples of 90 deg from one another, they will have
+ // different AA boxes. (For an explanation of AA boxes, see comments in
+ // onEmitGeometryShader.) This means the coverage analysis will only be approximate. It
+ // seems acceptable, but if we want exact coverage we will need to switch to a more
+ // expensive model.
+ f->codeAppendf("for (int i = 0; i < 2; ++i) {"); // Loop through both edges.
+ f->codeAppendf( "half2 corner = %s[i];", fCornerLocationInAABoxes.fsIn());
+ f->codeAppendf( "half2 bisect = %s[i];", fBisectInAABoxes.fsIn());
+
+ // Find the point at which the bisector exits the logical AA box.
+ // (The inequality works because bisect.x is known >= 0 and bisect.y is known <= 0.)
+ f->codeAppendf( "half2 d = half2(1 - corner.x, -corner.y);");
+ f->codeAppendf( "half T = d.y * bisect.x >= d.x * bisect.y ? d.y / bisect.y "
+ ": d.x / bisect.x;");
+ f->codeAppendf( "half2 exit = corner + bisect * T;");
+
+ // These lines combined (and the final multiply by .5) accomplish the following:
+ // 1. Add back the area beyond the corner that was subtracted out previously.
+ // 2. Subtract out the area beyond the corner, but under the bisector.
+ // The other edge will take care of the area on its own side of the bisector.
+ f->codeAppendf( "%s += (2 - corner.x - exit.x) * corner.y;", outputCoverage);
+ f->codeAppendf( "%s += (corner.x - 1) * exit.y;", outputCoverage);
+ f->codeAppendf("}");
+
+ f->codeAppendf("%s *= .5;", outputCoverage);
+}