skia2/samplecode/SamplePathTessellators.cpp
Michael Ludwig 3518875c21 Avoid RAII wrappers around PatchWriter
Instead of CubicPatch(writer) << control points ... code now writes
writer << Cubic(controlPoints). The main benefit of this is that the
control points are available to the PatchWriter. This allows it (in
follow up CLs) to automatically chop the curves and track the last join
control point.

Change-Id: I38b57a141261afd42e511cc195eb5e64a2382263
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/501837
Reviewed-by: Christopher Dalton <csmartdalton@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
2022-02-03 02:30:52 +00:00

367 lines
13 KiB
C++

/*
* Copyright 2019 Google LLC.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "include/core/SkCanvas.h"
#include "samplecode/Sample.h"
#include "src/core/SkPathPriv.h"
#if SK_SUPPORT_GPU
#include "src/core/SkCanvasPriv.h"
#include "src/gpu/GrOpFlushState.h"
#include "src/gpu/GrRecordingContextPriv.h"
#include "src/gpu/ops/GrDrawOp.h"
#include "src/gpu/ops/GrSimpleMeshDrawOpHelper.h"
#include "src/gpu/ops/TessellationPathRenderer.h"
#include "src/gpu/tessellate/AffineMatrix.h"
#include "src/gpu/tessellate/PathCurveTessellator.h"
#include "src/gpu/tessellate/PathWedgeTessellator.h"
#include "src/gpu/tessellate/shaders/GrPathTessellationShader.h"
#include "src/gpu/v1/SurfaceDrawContext_v1.h"
namespace skgpu {
namespace {
enum class Mode {
kWedgeMiddleOut,
kCurveMiddleOut,
kWedgeTessellate,
kCurveTessellate
};
static const char* ModeName(Mode mode) {
switch (mode) {
case Mode::kWedgeMiddleOut:
return "MiddleOutShader (kWedges)";
case Mode::kCurveMiddleOut:
return "MiddleOutShader (kCurves)";
case Mode::kWedgeTessellate:
return "HardwareWedgeShader";
case Mode::kCurveTessellate:
return "HardwareCurveShader";
}
SkUNREACHABLE;
}
// Draws a path directly to the screen using a specific tessellator.
class SamplePathTessellatorOp : public GrDrawOp {
private:
DEFINE_OP_CLASS_ID
SamplePathTessellatorOp(const SkRect& drawBounds, const SkPath& path, const SkMatrix& m,
GrPipeline::InputFlags pipelineFlags, Mode mode)
: GrDrawOp(ClassID())
, fPath(path)
, fMatrix(m)
, fPipelineFlags(pipelineFlags)
, fMode(mode) {
this->setBounds(drawBounds, HasAABloat::kNo, IsHairline::kNo);
}
const char* name() const override { return "SamplePathTessellatorOp"; }
void visitProxies(const GrVisitProxyFunc&) const override {}
FixedFunctionFlags fixedFunctionFlags() const override {
return FixedFunctionFlags::kUsesHWAA;
}
GrProcessorSet::Analysis finalize(const GrCaps& caps, const GrAppliedClip* clip,
GrClampType clampType) override {
SkPMColor4f color;
return fProcessors.finalize(SK_PMColor4fWHITE, GrProcessorAnalysisCoverage::kNone, clip,
nullptr, caps, clampType, &color);
}
void onPrePrepare(GrRecordingContext*, const GrSurfaceProxyView&, GrAppliedClip*,
const GrDstProxyView&, GrXferBarrierFlags, GrLoadOp colorLoadOp) override {}
void onPrepare(GrOpFlushState* flushState) override {
constexpr static SkPMColor4f kCyan = {0,1,1,1};
auto alloc = flushState->allocator();
const SkMatrix& shaderMatrix = SkMatrix::I();
const SkMatrix& pathMatrix = fMatrix;
const GrCaps& caps = flushState->caps();
const GrShaderCaps& shaderCaps = *caps.shaderCaps();
int numVerbsToGetMiddleOut = 0;
int numVerbsToGetTessellation = caps.minPathVerbsForHwTessellation();
auto pipeline = GrSimpleMeshDrawOpHelper::CreatePipeline(flushState, std::move(fProcessors),
fPipelineFlags);
int numVerbs;
bool needsInnerFan;
switch (fMode) {
case Mode::kWedgeMiddleOut:
fTessellator = PathWedgeTessellator::Make(alloc, shaderCaps.infinitySupport());
numVerbs = numVerbsToGetMiddleOut;
needsInnerFan = false;
break;
case Mode::kCurveMiddleOut:
fTessellator = PathCurveTessellator::Make(alloc,
shaderCaps.infinitySupport());
numVerbs = numVerbsToGetMiddleOut;
needsInnerFan = true;
break;
case Mode::kWedgeTessellate:
fTessellator = PathWedgeTessellator::Make(alloc, shaderCaps.infinitySupport());
numVerbs = numVerbsToGetTessellation;
needsInnerFan = false;
break;
case Mode::kCurveTessellate:
fTessellator = PathCurveTessellator::Make(alloc,
shaderCaps.infinitySupport());
numVerbs = numVerbsToGetTessellation;
needsInnerFan = true;
break;
}
auto* tessShader = GrPathTessellationShader::Make(alloc,
shaderMatrix,
kCyan,
numVerbs,
*pipeline,
fTessellator->patchAttribs(),
caps);
fProgram = GrTessellationShader::MakeProgram({alloc, flushState->writeView(),
flushState->usesMSAASurface(),
&flushState->dstProxyView(),
flushState->renderPassBarriers(),
GrLoadOp::kClear, &flushState->caps()},
tessShader,
pipeline,
&GrUserStencilSettings::kUnused);
int patchPreallocCount = fTessellator->patchPreallocCount(fPath.countVerbs());
if (needsInnerFan) {
patchPreallocCount += fPath.countVerbs() - 1;
}
PatchWriter patchWriter(flushState, fTessellator, patchPreallocCount);
if (needsInnerFan) {
// Write out inner fan triangles.
AffineMatrix m(pathMatrix);
for (PathMiddleOutFanIter it(fPath); !it.done();) {
for (auto [p0, p1, p2] : it.nextStack()) {
auto [mp0, mp1] = m.map2Points(p0, p1);
auto mp2 = m.map1Point(&p2);
patchWriter << PatchWriter::Triangle(mp0, mp1, mp2);
}
}
}
// Write out the curves.
fTessellator->writePatches(patchWriter,
tessShader->maxTessellationSegments(*caps.shaderCaps()),
shaderMatrix,
{pathMatrix, fPath, kCyan});
if (!tessShader->willUseTessellationShaders()) {
fTessellator->prepareFixedCountBuffers(flushState);
}
}
void onExecute(GrOpFlushState* flushState, const SkRect& chainBounds) override {
flushState->bindPipeline(*fProgram, chainBounds);
fTessellator->draw(flushState, fProgram->geomProc().willUseTessellationShaders());
}
const SkPath fPath;
const SkMatrix fMatrix;
const GrPipeline::InputFlags fPipelineFlags;
const Mode fMode;
PathTessellator* fTessellator = nullptr;
GrProgramInfo* fProgram;
GrProcessorSet fProcessors{SkBlendMode::kSrcOver};
friend class GrOp; // For ctor.
};
} // namespace
// This sample enables wireframe and visualizes the triangles generated by path tessellators.
class SamplePathTessellators : public Sample {
public:
SamplePathTessellators() {
#if 0
// For viewing middle-out triangulations of the inner fan.
fPath.moveTo(1, 0);
int numSides = 32 * 3;
for (int i = 1; i < numSides; ++i) {
float theta = 2*3.1415926535897932384626433832785 * i / numSides;
fPath.lineTo(std::cos(theta), std::sin(theta));
}
fPath.transform(SkMatrix::Scale(200, 200));
fPath.transform(SkMatrix::Translate(300, 300));
#else
fPath.moveTo(100, 500);
fPath.cubicTo(300, 400, -100, 300, 100, 200);
fPath.quadTo(250, 0, 400, 200);
fPath.conicTo(600, 350, 400, 500, fConicWeight);
fPath.close();
#endif
}
private:
void onDrawContent(SkCanvas*) override;
Sample::Click* onFindClickHandler(SkScalar x, SkScalar y, skui::ModifierKey) override;
bool onClick(Sample::Click*) override;
bool onChar(SkUnichar) override;
SkString name() override { return SkString("PathTessellators"); }
SkPath fPath;
GrPipeline::InputFlags fPipelineFlags = GrPipeline::InputFlags::kWireframe;
Mode fMode = Mode::kWedgeMiddleOut;
float fConicWeight = .5;
class Click;
};
void SamplePathTessellators::onDrawContent(SkCanvas* canvas) {
canvas->clear(SK_ColorBLACK);
auto ctx = canvas->recordingContext();
auto sdc = SkCanvasPriv::TopDeviceSurfaceDrawContext(canvas);
SkString error;
if (!sdc || !ctx) {
error = "GPU Only.";
} else if (!skgpu::v1::TessellationPathRenderer::IsSupported(*ctx->priv().caps())) {
error = "TessellationPathRenderer not supported.";
} else if (fMode >= Mode::kWedgeTessellate &&
!ctx->priv().caps()->shaderCaps()->tessellationSupport()) {
error.printf("%s requires hardware tessellation support.", ModeName(fMode));
}
if (!error.isEmpty()) {
canvas->clear(SK_ColorRED);
SkFont font(nullptr, 20);
SkPaint captionPaint;
captionPaint.setColor(SK_ColorWHITE);
canvas->drawString(error.c_str(), 10, 30, font, captionPaint);
return;
}
sdc->addDrawOp(GrOp::Make<SamplePathTessellatorOp>(ctx,
sdc->asRenderTargetProxy()->getBoundsRect(),
fPath, canvas->getTotalMatrix(),
fPipelineFlags, fMode));
// Draw the path points.
SkPaint pointsPaint;
pointsPaint.setColor(SK_ColorBLUE);
pointsPaint.setStrokeWidth(8);
SkPath devPath = fPath;
devPath.transform(canvas->getTotalMatrix());
{
SkAutoCanvasRestore acr(canvas, true);
canvas->setMatrix(SkMatrix::I());
SkString caption(ModeName(fMode));
caption.appendf(" (w=%g)", fConicWeight);
SkFont font(nullptr, 20);
SkPaint captionPaint;
captionPaint.setColor(SK_ColorWHITE);
canvas->drawString(caption, 10, 30, font, captionPaint);
canvas->drawPoints(SkCanvas::kPoints_PointMode, devPath.countPoints(),
SkPathPriv::PointData(devPath), pointsPaint);
}
}
class SamplePathTessellators::Click : public Sample::Click {
public:
Click(int ptIdx) : fPtIdx(ptIdx) {}
void doClick(SkPath* path) {
SkPoint pt = path->getPoint(fPtIdx);
SkPathPriv::UpdatePathPoint(path, fPtIdx, pt + fCurr - fPrev);
}
private:
int fPtIdx;
};
Sample::Click* SamplePathTessellators::onFindClickHandler(SkScalar x, SkScalar y,
skui::ModifierKey) {
const SkPoint* pts = SkPathPriv::PointData(fPath);
float fuzz = 30;
for (int i = 0; i < fPath.countPoints(); ++i) {
if (fabs(x - pts[i].x()) < fuzz && fabsf(y - pts[i].y()) < fuzz) {
return new Click(i);
}
}
return nullptr;
}
bool SamplePathTessellators::onClick(Sample::Click* click) {
Click* myClick = (Click*)click;
myClick->doClick(&fPath);
return true;
}
static SkPath update_weight(const SkPath& path, float w) {
SkPath path_;
for (auto [verb, pts, _] : SkPathPriv::Iterate(path)) {
switch (verb) {
case SkPathVerb::kMove:
path_.moveTo(pts[0]);
break;
case SkPathVerb::kLine:
path_.lineTo(pts[1]);
break;
case SkPathVerb::kQuad:
path_.quadTo(pts[1], pts[2]);
break;
case SkPathVerb::kCubic:
path_.cubicTo(pts[1], pts[2], pts[3]);
break;
case SkPathVerb::kConic:
path_.conicTo(pts[1], pts[2], (w != 1) ? w : .99f);
break;
case SkPathVerb::kClose:
break;
}
}
return path_;
}
bool SamplePathTessellators::onChar(SkUnichar unichar) {
switch (unichar) {
case 'w':
fPipelineFlags = (GrPipeline::InputFlags)(
(int)fPipelineFlags ^ (int)GrPipeline::InputFlags::kWireframe);
return true;
case 'D': {
fPath.dump();
return true;
}
case '+':
fConicWeight *= 2;
fPath = update_weight(fPath, fConicWeight);
return true;
case '=':
fConicWeight *= 5/4.f;
fPath = update_weight(fPath, fConicWeight);
return true;
case '_':
fConicWeight *= .5f;
fPath = update_weight(fPath, fConicWeight);
return true;
case '-':
fConicWeight *= 4/5.f;
fPath = update_weight(fPath, fConicWeight);
return true;
case '1':
case '2':
case '3':
case '4':
fMode = (Mode)(unichar - '1');
return true;
}
return false;
}
Sample* MakeTessellatedPathSample() { return new SamplePathTessellators; }
static SampleRegistry gTessellatedPathSample(MakeTessellatedPathSample);
} // namespace skgpu
#endif // SK_SUPPORT_GPU