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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 "GrCCPRTriangleProcessor.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "glsl/GrGLSLGeometryShaderBuilder.h"
#include "glsl/GrGLSLVertexShaderBuilder.h"
void GrCCPRTriangleProcessor::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[sk_VertexID]", proc.instanceAttrib()).c_str());
v->codeAppendf(".xy + %s;", atlasOffset);
gpArgs->fPositionVar.set(kVec2f_GrSLType, "self");
}
void GrCCPRTriangleProcessor::defineInputVertices(GrGLSLGeometryBuilder* g) const {
// Prepend in_vertices at the start of the shader.
g->codePrependf("highp float3x2 in_vertices = float3x2(sk_in[0].gl_Position.xy, "
"sk_in[1].gl_Position.xy, "
"sk_in[2].gl_Position.xy);");
}
void GrCCPRTriangleProcessor::emitWind(GrGLSLGeometryBuilder* g, const char* /*rtAdjust*/,
const char* outputWind) const {
// We will define in_vertices in defineInputVertices.
g->codeAppendf("%s = sign(determinant(float2x2(in_vertices[1] - in_vertices[0], "
"in_vertices[2] - in_vertices[0])));",
outputWind);
}
void GrCCPRTriangleHullAndEdgeProcessor::onEmitGeometryShader(GrGLSLGeometryBuilder* g,
const char* emitVertexFn,
const char* wind,
const char* rtAdjust) const {
this->defineInputVertices(g);
int maxOutputVertices = 0;
if (GeometryType::kEdges != fGeometryType) {
maxOutputVertices += this->emitHullGeometry(g, emitVertexFn, "in_vertices", 3,
"sk_InvocationID");
}
if (GeometryType::kHulls != fGeometryType) {
g->codeAppend ("int edgeidx0 = sk_InvocationID, "
"edgeidx1 = (edgeidx0 + 1) % 3;");
g->codeAppendf("highp float2 edgept0 = in_vertices[%s > 0 ? edgeidx0 : edgeidx1];", wind);
g->codeAppendf("highp float2 edgept1 = in_vertices[%s > 0 ? edgeidx1 : edgeidx0];", wind);
maxOutputVertices += this->emitEdgeGeometry(g, emitVertexFn, "edgept0", "edgept1");
}
g->configure(GrGLSLGeometryBuilder::InputType::kTriangles,
GrGLSLGeometryBuilder::OutputType::kTriangleStrip,
maxOutputVertices, 3);
}
void GrCCPRTriangleCornerProcessor::onEmitVertexShader(const GrCCPRCoverageProcessor& proc,
GrGLSLVertexBuilder* v,
const TexelBufferHandle& pointsBuffer,
const char* atlasOffset,
const char* rtAdjust,
GrGPArgs* gpArgs) const {
this->INHERITED::onEmitVertexShader(proc, v, pointsBuffer, atlasOffset, rtAdjust, gpArgs);
// Fetch and transform the next point in the triangle.
v->codeAppend ("highp float2 next = ");
v->appendTexelFetch(pointsBuffer,
SkStringPrintf("%s[(sk_VertexID+1) %% 3]", proc.instanceAttrib()).c_str());
v->codeAppendf(".xy + %s;", atlasOffset);
// Find the plane that gives distance from the [self -> next] edge, normalized to its AA
// bloat width.
v->codeAppend ("highp float2 n = float2(next.y - self.y, self.x - next.x);");
v->codeAppendf("highp float2 d = n * float2x2(self + %f * sign(n), "
"self - %f * sign(n));",
kAABloatRadius, kAABloatRadius);
// Clamp for when n=0. (wind=0 when n=0, so as long as we don't get Inf or NaN we are fine.)
v->codeAppendf("%s.xy = n / max(d[0] - d[1], 1e-30);", fEdgeDistance.vsOut());
v->codeAppendf("%s.z = -dot(%s.xy, self);", fEdgeDistance.vsOut(), fEdgeDistance.vsOut());
// Emit device coords to geo shader.
v->codeAppendf("%s = self;", fDevCoord.vsOut());
}
void GrCCPRTriangleCornerProcessor::onEmitGeometryShader(GrGLSLGeometryBuilder* g,
const char* emitVertexFn, const char* wind,
const char* rtAdjust) const {
this->defineInputVertices(g);
g->codeAppend ("highp float2 self = in_vertices[sk_InvocationID];");
int numVertices = this->emitCornerGeometry(g, emitVertexFn, "self");
g->configure(GrGLSLGeometryBuilder::InputType::kTriangles,
GrGLSLGeometryBuilder::OutputType::kTriangleStrip,
numVertices, 3);
}
void GrCCPRTriangleCornerProcessor::emitPerVertexGeometryCode(SkString* fnBody,
const char* position,
const char* /*coverage*/,
const char* wind) const {
fnBody->appendf("%s.xy = %s[(sk_InvocationID + 1) %% 3];",
fNeighbors.gsOut(), fDevCoord.gsIn());
fnBody->appendf("%s.zw = %s[(sk_InvocationID + 2) %% 3];",
fNeighbors.gsOut(), fDevCoord.gsIn());
fnBody->appendf("%s = float3x3(%s[(sk_InvocationID + 2) %% 3], "
"%s[sk_InvocationID], "
"%s[(sk_InvocationID + 1) %% 3]) * %s;",
fEdgeDistances.gsOut(), fEdgeDistance.gsIn(), fEdgeDistance.gsIn(),
fEdgeDistance.gsIn(), wind);
// Otherwise, fEdgeDistances = float3x3(...) * sign(wind * rtAdjust.x * rdAdjust.z).
GR_STATIC_ASSERT(kTopLeft_GrSurfaceOrigin == GrCCPRCoverageProcessor::kAtlasOrigin);
fnBody->appendf("%s = sk_InvocationID;", fCornerIdx.gsOut());
}
void GrCCPRTriangleCornerProcessor::emitShaderCoverage(GrGLSLFragmentBuilder* f,
const char* outputCoverage) const {
// FIXME: Adreno breaks if we don't put the frag coord in an intermediate highp variable.
f->codeAppendf("highp float2 fragcoord = sk_FragCoord.xy;");
// Approximate coverage by tracking where 4 horizontal lines enter and leave the triangle.
GrShaderVar samples("samples", kVec4f_GrSLType, GrShaderVar::kNonArray,
kHigh_GrSLPrecision);
f->declareGlobal(samples);
f->codeAppendf("%s = fragcoord.y + float4(-0.375, -0.125, 0.125, 0.375);", samples.c_str());
GrShaderVar leftedge("leftedge", kVec4f_GrSLType, GrShaderVar::kNonArray,
kHigh_GrSLPrecision);
f->declareGlobal(leftedge);
f->codeAppendf("%s = float4(fragcoord.x - 0.5);", leftedge.c_str());
GrShaderVar rightedge("rightedge", kVec4f_GrSLType, GrShaderVar::kNonArray,
kHigh_GrSLPrecision);
f->declareGlobal(rightedge);
f->codeAppendf("%s = float4(fragcoord.x + 0.5);", rightedge.c_str());
SkString sampleEdgeFn;
GrShaderVar edgeArg("edge_distance", kVec3f_GrSLType, GrShaderVar::kNonArray,
kHigh_GrSLPrecision);
f->emitFunction(kVoid_GrSLType, "sampleEdge", 1, &edgeArg, [&]() {
SkString b;
b.appendf("highp float m = abs(%s.x) < 1e-3 ? 1e18 : -1 / %s.x;",
edgeArg.c_str(), edgeArg.c_str());
b.appendf("highp float4 edge = m * (%s.y * samples + %s.z);",
edgeArg.c_str(), edgeArg.c_str());
b.appendf("if (%s.x <= 1e-3 || (abs(%s.x) < 1e-3 && %s.y > 0)) {",
edgeArg.c_str(), edgeArg.c_str(), edgeArg.c_str());
b.appendf( "%s = max(%s, edge);", leftedge.c_str(), leftedge.c_str());
b.append ("} else {");
b.appendf( "%s = min(%s, edge);", rightedge.c_str(), rightedge.c_str());
b.append ("}");
return b;
}().c_str(), &sampleEdgeFn);
// See if the previous neighbor already handled this pixel.
f->codeAppendf("if (all(lessThan(abs(fragcoord - %s.zw), float2(%f)))) {",
fNeighbors.fsIn(), kAABloatRadius);
// Handle the case where all 3 corners defer to the previous neighbor.
f->codeAppendf( "if (%s != 0 || !all(lessThan(abs(fragcoord - %s.xy), float2(%f)))) {",
fCornerIdx.fsIn(), fNeighbors.fsIn(), kAABloatRadius);
f->codeAppend ( "discard;");
f->codeAppend ( "}");
f->codeAppend ("}");
// Erase what the hull and two edges wrote at this corner in previous shaders (the two .5's
// for the edges and the -1 for the hull cancel each other out).
f->codeAppendf("%s = dot(float3(fragcoord, 1) * float2x3(%s), float2(1));",
outputCoverage, fEdgeDistances.fsIn());
// Sample the two edges at this corner.
f->codeAppendf("%s(%s[0]);", sampleEdgeFn.c_str(), fEdgeDistances.fsIn());
f->codeAppendf("%s(%s[1]);", sampleEdgeFn.c_str(), fEdgeDistances.fsIn());
// Handle the opposite edge if the next neighbor will defer to us.
f->codeAppendf("if (all(lessThan(abs(fragcoord - %s.xy), float2(%f)))) {",
fNeighbors.fsIn(), kAABloatRadius);
// Erase the coverage the opposite edge wrote to this corner.
f->codeAppendf( "%s += dot(%s[2], float3(fragcoord, 1)) + 0.5;",
outputCoverage, fEdgeDistances.fsIn());
// Sample the opposite edge.
f->codeAppendf( "%s(%s[2]);", sampleEdgeFn.c_str(), fEdgeDistances.fsIn());
f->codeAppend ("}");
f->codeAppendf("highp float4 widths = max(%s - %s, 0);", rightedge.c_str(), leftedge.c_str());
f->codeAppendf("%s += dot(widths, float4(0.25));", outputCoverage);
}
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