/*
* 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 "GrCCPathProcessor.h"
#include "GrGpuCommandBuffer.h"
#include "GrOnFlushResourceProvider.h"
#include "GrTexture.h"
#include "ccpr/GrCCPerFlushResources.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "glsl/GrGLSLGeometryProcessor.h"
#include "glsl/GrGLSLProgramBuilder.h"
#include "glsl/GrGLSLVarying.h"
// Paths are drawn as octagons. Each point on the octagon is the intersection of two lines: one edge
// from the path's bounding box and one edge from its 45-degree bounding box. The below inputs
// define a vertex by the two edges that need to be intersected. Normals point out of the octagon,
// and the bounding boxes are sent in as instance attribs.
static constexpr float kOctoEdgeNorms[8 * 4] = {
// bbox // bbox45
-1, 0, -1,+1,
-1, 0, -1,-1,
0,-1, -1,-1,
0,-1, +1,-1,
+1, 0, +1,-1,
+1, 0, +1,+1,
0,+1, +1,+1,
0,+1, -1,+1,
};
GR_DECLARE_STATIC_UNIQUE_KEY(gVertexBufferKey);
sk_sp<const GrBuffer> GrCCPathProcessor::FindVertexBuffer(GrOnFlushResourceProvider* onFlushRP) {
GR_DEFINE_STATIC_UNIQUE_KEY(gVertexBufferKey);
return onFlushRP->findOrMakeStaticBuffer(kVertex_GrBufferType, sizeof(kOctoEdgeNorms),
kOctoEdgeNorms, gVertexBufferKey);
}
static constexpr uint16_t kRestartStrip = 0xffff;
static constexpr uint16_t kOctoIndicesAsStrips[] = {
1, 0, 2, 4, 3, kRestartStrip, // First half.
5, 4, 6, 0, 7 // Second half.
};
static constexpr uint16_t kOctoIndicesAsTris[] = {
// First half.
1, 0, 2,
0, 4, 2,
2, 4, 3,
// Second half.
5, 4, 6,
4, 0, 6,
6, 0, 7,
};
GR_DECLARE_STATIC_UNIQUE_KEY(gIndexBufferKey);
constexpr GrPrimitiveProcessor::Attribute GrCCPathProcessor::kInstanceAttribs[];
constexpr GrPrimitiveProcessor::Attribute GrCCPathProcessor::kEdgeNormsAttrib;
sk_sp<const GrBuffer> GrCCPathProcessor::FindIndexBuffer(GrOnFlushResourceProvider* onFlushRP) {
GR_DEFINE_STATIC_UNIQUE_KEY(gIndexBufferKey);
if (onFlushRP->caps()->usePrimitiveRestart()) {
return onFlushRP->findOrMakeStaticBuffer(kIndex_GrBufferType, sizeof(kOctoIndicesAsStrips),
kOctoIndicesAsStrips, gIndexBufferKey);
} else {
return onFlushRP->findOrMakeStaticBuffer(kIndex_GrBufferType, sizeof(kOctoIndicesAsTris),
kOctoIndicesAsTris, gIndexBufferKey);
}
}
GrCCPathProcessor::GrCCPathProcessor(const GrTextureProxy* atlas,
const SkMatrix& viewMatrixIfUsingLocalCoords)
: INHERITED(kGrCCPathProcessor_ClassID)
, fAtlasAccess(atlas->textureType(), atlas->config(), GrSamplerState::Filter::kNearest,
GrSamplerState::WrapMode::kClamp)
, fAtlasSize(atlas->isize())
, fAtlasOrigin(atlas->origin()) {
// TODO: Can we just assert that atlas has GrCCAtlas::kTextureOrigin and remove fAtlasOrigin?
this->setInstanceAttributes(kInstanceAttribs, kNumInstanceAttribs);
SkASSERT(this->instanceStride() == sizeof(Instance));
this->setVertexAttributes(&kEdgeNormsAttrib, 1);
this->setTextureSamplerCnt(1);
if (!viewMatrixIfUsingLocalCoords.invert(&fLocalMatrix)) {
fLocalMatrix.setIdentity();
}
}
class GLSLPathProcessor : public GrGLSLGeometryProcessor {
public:
void onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) override;
private:
void setData(const GrGLSLProgramDataManager& pdman, const GrPrimitiveProcessor& primProc,
FPCoordTransformIter&& transformIter) override {
const GrCCPathProcessor& proc = primProc.cast<GrCCPathProcessor>();
pdman.set2f(fAtlasAdjustUniform, 1.0f / proc.atlasSize().fWidth,
1.0f / proc.atlasSize().fHeight);
this->setTransformDataHelper(proc.localMatrix(), pdman, &transformIter);
}
GrGLSLUniformHandler::UniformHandle fAtlasAdjustUniform;
typedef GrGLSLGeometryProcessor INHERITED;
};
GrGLSLPrimitiveProcessor* GrCCPathProcessor::createGLSLInstance(const GrShaderCaps&) const {
return new GLSLPathProcessor();
}
void GrCCPathProcessor::drawPaths(GrOpFlushState* flushState, const GrPipeline& pipeline,
const GrPipeline::FixedDynamicState* fixedDynamicState,
const GrCCPerFlushResources& resources, int baseInstance,
int endInstance, const SkRect& bounds) const {
const GrCaps& caps = flushState->caps();
GrPrimitiveType primitiveType = caps.usePrimitiveRestart()
? GrPrimitiveType::kTriangleStrip
: GrPrimitiveType::kTriangles;
int numIndicesPerInstance = caps.usePrimitiveRestart()
? SK_ARRAY_COUNT(kOctoIndicesAsStrips)
: SK_ARRAY_COUNT(kOctoIndicesAsTris);
GrMesh mesh(primitiveType);
auto enablePrimitiveRestart = GrPrimitiveRestart(flushState->caps().usePrimitiveRestart());
mesh.setIndexedInstanced(resources.refIndexBuffer(), numIndicesPerInstance,
resources.refInstanceBuffer(), endInstance - baseInstance,
baseInstance, enablePrimitiveRestart);
mesh.setVertexData(resources.refVertexBuffer());
flushState->rtCommandBuffer()->draw(*this, pipeline, fixedDynamicState, nullptr, &mesh, 1,
bounds);
}
void GLSLPathProcessor::onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) {
using InstanceAttribs = GrCCPathProcessor::InstanceAttribs;
using Interpolation = GrGLSLVaryingHandler::Interpolation;
const GrCCPathProcessor& proc = args.fGP.cast<GrCCPathProcessor>();
GrGLSLUniformHandler* uniHandler = args.fUniformHandler;
GrGLSLVaryingHandler* varyingHandler = args.fVaryingHandler;
const char* atlasAdjust;
fAtlasAdjustUniform = uniHandler->addUniform(
kVertex_GrShaderFlag,
kFloat2_GrSLType, "atlas_adjust", &atlasAdjust);
varyingHandler->emitAttributes(proc);
GrGLSLVarying texcoord(kFloat3_GrSLType);
GrGLSLVarying color(kHalf4_GrSLType);
varyingHandler->addVarying("texcoord", &texcoord);
varyingHandler->addPassThroughAttribute(proc.getInstanceAttrib(InstanceAttribs::kColor),
args.fOutputColor, Interpolation::kCanBeFlat);
// The vertex shader bloats and intersects the devBounds and devBounds45 rectangles, in order to
// find an octagon that circumscribes the (bloated) path.
GrGLSLVertexBuilder* v = args.fVertBuilder;
// Each vertex is the intersection of one edge from devBounds and one from devBounds45.
// 'N' holds the normals to these edges as column vectors.
//
// NOTE: "float2x2(float4)" is valid and equivalent to "float2x2(float4.xy, float4.zw)",
// however Intel compilers crash when we use the former syntax in this shader.
v->codeAppendf("float2x2 N = float2x2(%s.xy, %s.zw);", proc.getEdgeNormsAttrib().name(),
proc.getEdgeNormsAttrib().name());
// N[0] is the normal for the edge we are intersecting from the regular bounding box, pointing
// out of the octagon.
v->codeAppendf("float4 devbounds = %s;",
proc.getInstanceAttrib(InstanceAttribs::kDevBounds).name());
v->codeAppend ("float2 refpt = (0 == sk_VertexID >> 2)"
"? float2(min(devbounds.x, devbounds.z), devbounds.y)"
": float2(max(devbounds.x, devbounds.z), devbounds.w);");
// N[1] is the normal for the edge we are intersecting from the 45-degree bounding box, pointing
// out of the octagon.
v->codeAppendf("float2 refpt45 = (0 == ((sk_VertexID + 1) & (1 << 2))) ? %s.xy : %s.zw;",
proc.getInstanceAttrib(InstanceAttribs::kDevBounds45).name(),
proc.getInstanceAttrib(InstanceAttribs::kDevBounds45).name());
v->codeAppendf("refpt45 *= float2x2(.5,.5,-.5,.5);"); // transform back to device space.
v->codeAppend ("float2 K = float2(dot(N[0], refpt), dot(N[1], refpt45));");
v->codeAppendf("float2 octocoord = K * inverse(N);");
// Round the octagon out to ensure we rasterize every pixel the path might touch. (Positive
// bloatdir means we should take the "ceil" and negative means to take the "floor".)
//
// NOTE: If we were just drawing a rect, ceil/floor would be enough. But since there are also
// diagonals in the octagon that cross through pixel centers, we need to outset by another
// quarter px to ensure those pixels get rasterized.
v->codeAppend ("float2 bloatdir = (0 != N[0].x) "
"? half2(N[0].x, N[1].y) : half2(N[1].x, N[0].y);");
v->codeAppend ("octocoord = (ceil(octocoord * bloatdir - 1e-4) + 0.25) * bloatdir;");
gpArgs->fPositionVar.set(kFloat2_GrSLType, "octocoord");
// Convert to atlas coordinates in order to do our texture lookup.
v->codeAppendf("float2 atlascoord = octocoord + float2(%s);",
proc.getInstanceAttrib(InstanceAttribs::kDevToAtlasOffset).name());
if (kTopLeft_GrSurfaceOrigin == proc.atlasOrigin()) {
v->codeAppendf("%s.xy = atlascoord * %s;", texcoord.vsOut(), atlasAdjust);
} else {
SkASSERT(kBottomLeft_GrSurfaceOrigin == proc.atlasOrigin());
v->codeAppendf("%s.xy = float2(atlascoord.x * %s.x, 1 - atlascoord.y * %s.y);",
texcoord.vsOut(), atlasAdjust, atlasAdjust);
}
// The third texture coordinate is -.5 for even-odd paths and +.5 for winding ones.
// ("right < left" indicates even-odd fill type.)
v->codeAppendf("%s.z = sign(devbounds.z - devbounds.x) * .5;", texcoord.vsOut());
this->emitTransforms(v, varyingHandler, uniHandler, GrShaderVar("octocoord", kFloat2_GrSLType),
proc.localMatrix(), args.fFPCoordTransformHandler);
// Fragment shader.
GrGLSLFPFragmentBuilder* f = args.fFragBuilder;
// Look up coverage count in the atlas.
f->codeAppend ("half coverage = ");
f->appendTextureLookup(args.fTexSamplers[0], SkStringPrintf("%s.xy", texcoord.fsIn()).c_str(),
kFloat2_GrSLType);
f->codeAppend (".a;");
// Scale coverage count by .5. Make it negative for even-odd paths and positive for winding
// ones. Clamp winding coverage counts at 1.0 (i.e. min(coverage/2, .5)).
f->codeAppendf("coverage = min(abs(coverage) * %s.z, .5);", texcoord.fsIn());
// For negative values, this finishes the even-odd sawtooth function. Since positive (winding)
// values were clamped at "coverage/2 = .5", this only undoes the previous multiply by .5.
f->codeAppend ("coverage = 1 - abs(fract(coverage) * 2 - 1);");
f->codeAppendf("%s = half4(coverage);", args.fOutputCoverage);
}