123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878879880881882883884885886887888889890891892893894895896897898899900901902903904905906907908909910911912913914915916917918919920921922923924925926927928929930931932933934935936937938939940941942943944945946947948949950951952953954955956957958959960961962963964965966967968969970971972973974975976977978979980981982983984985986987988989990991992993994995996997998999100010011002100310041005100610071008100910101011101210131014101510161017101810191020102110221023102410251026102710281029103010311032103310341035103610371038103910401041104210431044104510461047104810491050105110521053105410551056105710581059106010611062106310641065106610671068106910701071107210731074107510761077107810791080108110821083108410851086108710881089109010911092109310941095109610971098109911001101110211031104 |
- /*
- * Copyright 2015 Google Inc.
- *
- * 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 "include/core/SkPath.h"
- #include "include/core/SkPoint.h"
- #include "include/core/SkString.h"
- #include "src/gpu/geometry/GrPathUtils.h"
- #include "src/gpu/ops/GrAAConvexTessellator.h"
- // Next steps:
- // add an interactive sample app slide
- // add debug check that all points are suitably far apart
- // test more degenerate cases
- // The tolerance for fusing vertices and eliminating colinear lines (It is in device space).
- static const SkScalar kClose = (SK_Scalar1 / 16);
- static const SkScalar kCloseSqd = kClose * kClose;
- // tesselation tolerance values, in device space pixels
- static const SkScalar kQuadTolerance = 0.2f;
- static const SkScalar kCubicTolerance = 0.2f;
- static const SkScalar kConicTolerance = 0.25f;
- // dot product below which we use a round cap between curve segments
- static const SkScalar kRoundCapThreshold = 0.8f;
- // dot product above which we consider two adjacent curves to be part of the "same" curve
- static const SkScalar kCurveConnectionThreshold = 0.8f;
- static bool intersect(const SkPoint& p0, const SkPoint& n0,
- const SkPoint& p1, const SkPoint& n1,
- SkScalar* t) {
- const SkPoint v = p1 - p0;
- SkScalar perpDot = n0.fX * n1.fY - n0.fY * n1.fX;
- if (SkScalarNearlyZero(perpDot)) {
- return false;
- }
- *t = (v.fX * n1.fY - v.fY * n1.fX) / perpDot;
- SkASSERT(SkScalarIsFinite(*t));
- return true;
- }
- // This is a special case version of intersect where we have the vector
- // perpendicular to the second line rather than the vector parallel to it.
- static SkScalar perp_intersect(const SkPoint& p0, const SkPoint& n0,
- const SkPoint& p1, const SkPoint& perp) {
- const SkPoint v = p1 - p0;
- SkScalar perpDot = n0.dot(perp);
- return v.dot(perp) / perpDot;
- }
- static bool duplicate_pt(const SkPoint& p0, const SkPoint& p1) {
- SkScalar distSq = SkPointPriv::DistanceToSqd(p0, p1);
- return distSq < kCloseSqd;
- }
- static bool points_are_colinear_and_b_is_middle(const SkPoint& a, const SkPoint& b,
- const SkPoint& c) {
- // 'area' is twice the area of the triangle with corners a, b, and c.
- SkScalar area = a.fX * (b.fY - c.fY) + b.fX * (c.fY - a.fY) + c.fX * (a.fY - b.fY);
- if (SkScalarAbs(area) >= 2 * kCloseSqd) {
- return false;
- }
- return (a - b).dot(b - c) >= 0;
- }
- int GrAAConvexTessellator::addPt(const SkPoint& pt,
- SkScalar depth,
- SkScalar coverage,
- bool movable,
- CurveState curve) {
- SkASSERT(pt.isFinite());
- this->validate();
- int index = fPts.count();
- *fPts.push() = pt;
- *fCoverages.push() = coverage;
- *fMovable.push() = movable;
- *fCurveState.push() = curve;
- this->validate();
- return index;
- }
- void GrAAConvexTessellator::popLastPt() {
- this->validate();
- fPts.pop();
- fCoverages.pop();
- fMovable.pop();
- fCurveState.pop();
- this->validate();
- }
- void GrAAConvexTessellator::popFirstPtShuffle() {
- this->validate();
- fPts.removeShuffle(0);
- fCoverages.removeShuffle(0);
- fMovable.removeShuffle(0);
- fCurveState.removeShuffle(0);
- this->validate();
- }
- void GrAAConvexTessellator::updatePt(int index,
- const SkPoint& pt,
- SkScalar depth,
- SkScalar coverage) {
- this->validate();
- SkASSERT(fMovable[index]);
- fPts[index] = pt;
- fCoverages[index] = coverage;
- }
- void GrAAConvexTessellator::addTri(int i0, int i1, int i2) {
- if (i0 == i1 || i1 == i2 || i2 == i0) {
- return;
- }
- *fIndices.push() = i0;
- *fIndices.push() = i1;
- *fIndices.push() = i2;
- }
- void GrAAConvexTessellator::rewind() {
- fPts.rewind();
- fCoverages.rewind();
- fMovable.rewind();
- fIndices.rewind();
- fNorms.rewind();
- fCurveState.rewind();
- fInitialRing.rewind();
- fCandidateVerts.rewind();
- #if GR_AA_CONVEX_TESSELLATOR_VIZ
- fRings.rewind(); // TODO: leak in this case!
- #else
- fRings[0].rewind();
- fRings[1].rewind();
- #endif
- }
- void GrAAConvexTessellator::computeNormals() {
- auto normalToVector = [this](SkVector v) {
- SkVector n = SkPointPriv::MakeOrthog(v, fSide);
- SkAssertResult(n.normalize());
- SkASSERT(SkScalarNearlyEqual(1.0f, n.length()));
- return n;
- };
- // Check the cross product of the final trio
- fNorms.append(fPts.count());
- fNorms[0] = fPts[1] - fPts[0];
- fNorms.top() = fPts[0] - fPts.top();
- SkScalar cross = SkPoint::CrossProduct(fNorms[0], fNorms.top());
- fSide = (cross > 0.0f) ? SkPointPriv::kRight_Side : SkPointPriv::kLeft_Side;
- fNorms[0] = normalToVector(fNorms[0]);
- for (int cur = 1; cur < fNorms.count() - 1; ++cur) {
- fNorms[cur] = normalToVector(fPts[cur + 1] - fPts[cur]);
- }
- fNorms.top() = normalToVector(fNorms.top());
- }
- void GrAAConvexTessellator::computeBisectors() {
- fBisectors.setCount(fNorms.count());
- int prev = fBisectors.count() - 1;
- for (int cur = 0; cur < fBisectors.count(); prev = cur, ++cur) {
- fBisectors[cur] = fNorms[cur] + fNorms[prev];
- if (!fBisectors[cur].normalize()) {
- fBisectors[cur] = SkPointPriv::MakeOrthog(fNorms[cur], (SkPointPriv::Side)-fSide) +
- SkPointPriv::MakeOrthog(fNorms[prev], fSide);
- SkAssertResult(fBisectors[cur].normalize());
- } else {
- fBisectors[cur].negate(); // make the bisector face in
- }
- if (fCurveState[prev] == kIndeterminate_CurveState) {
- if (fCurveState[cur] == kSharp_CurveState) {
- fCurveState[prev] = kSharp_CurveState;
- } else {
- if (SkScalarAbs(fNorms[cur].dot(fNorms[prev])) > kCurveConnectionThreshold) {
- fCurveState[prev] = kCurve_CurveState;
- fCurveState[cur] = kCurve_CurveState;
- } else {
- fCurveState[prev] = kSharp_CurveState;
- fCurveState[cur] = kSharp_CurveState;
- }
- }
- }
- SkASSERT(SkScalarNearlyEqual(1.0f, fBisectors[cur].length()));
- }
- }
- // Create as many rings as we need to (up to a predefined limit) to reach the specified target
- // depth. If we are in fill mode, the final ring will automatically be fanned.
- bool GrAAConvexTessellator::createInsetRings(Ring& previousRing, SkScalar initialDepth,
- SkScalar initialCoverage, SkScalar targetDepth,
- SkScalar targetCoverage, Ring** finalRing) {
- static const int kMaxNumRings = 8;
- if (previousRing.numPts() < 3) {
- return false;
- }
- Ring* currentRing = &previousRing;
- int i;
- for (i = 0; i < kMaxNumRings; ++i) {
- Ring* nextRing = this->getNextRing(currentRing);
- SkASSERT(nextRing != currentRing);
- bool done = this->createInsetRing(*currentRing, nextRing, initialDepth, initialCoverage,
- targetDepth, targetCoverage, i == 0);
- currentRing = nextRing;
- if (done) {
- break;
- }
- currentRing->init(*this);
- }
- if (kMaxNumRings == i) {
- // Bail if we've exceeded the amount of time we want to throw at this.
- this->terminate(*currentRing);
- return false;
- }
- bool done = currentRing->numPts() >= 3;
- if (done) {
- currentRing->init(*this);
- }
- *finalRing = currentRing;
- return done;
- }
- // The general idea here is to, conceptually, start with the original polygon and slide
- // the vertices along the bisectors until the first intersection. At that
- // point two of the edges collapse and the process repeats on the new polygon.
- // The polygon state is captured in the Ring class while the GrAAConvexTessellator
- // controls the iteration. The CandidateVerts holds the formative points for the
- // next ring.
- bool GrAAConvexTessellator::tessellate(const SkMatrix& m, const SkPath& path) {
- if (!this->extractFromPath(m, path)) {
- return false;
- }
- SkScalar coverage = 1.0f;
- SkScalar scaleFactor = 0.0f;
- if (SkStrokeRec::kStrokeAndFill_Style == fStyle) {
- SkASSERT(m.isSimilarity());
- scaleFactor = m.getMaxScale(); // x and y scale are the same
- SkScalar effectiveStrokeWidth = scaleFactor * fStrokeWidth;
- Ring outerStrokeAndAARing;
- this->createOuterRing(fInitialRing,
- effectiveStrokeWidth / 2 + kAntialiasingRadius, 0.0,
- &outerStrokeAndAARing);
- // discard all the triangles added between the originating ring and the new outer ring
- fIndices.rewind();
- outerStrokeAndAARing.init(*this);
- outerStrokeAndAARing.makeOriginalRing();
- // Add the outer stroke ring's normals to the originating ring's normals
- // so it can also act as an originating ring
- fNorms.setCount(fNorms.count() + outerStrokeAndAARing.numPts());
- for (int i = 0; i < outerStrokeAndAARing.numPts(); ++i) {
- SkASSERT(outerStrokeAndAARing.index(i) < fNorms.count());
- fNorms[outerStrokeAndAARing.index(i)] = outerStrokeAndAARing.norm(i);
- }
- // the bisectors are only needed for the computation of the outer ring
- fBisectors.rewind();
- Ring* insetAARing;
- this->createInsetRings(outerStrokeAndAARing,
- 0.0f, 0.0f, 2*kAntialiasingRadius, 1.0f,
- &insetAARing);
- SkDEBUGCODE(this->validate();)
- return true;
- }
- if (SkStrokeRec::kStroke_Style == fStyle) {
- SkASSERT(fStrokeWidth >= 0.0f);
- SkASSERT(m.isSimilarity());
- scaleFactor = m.getMaxScale(); // x and y scale are the same
- SkScalar effectiveStrokeWidth = scaleFactor * fStrokeWidth;
- Ring outerStrokeRing;
- this->createOuterRing(fInitialRing, effectiveStrokeWidth / 2 - kAntialiasingRadius,
- coverage, &outerStrokeRing);
- outerStrokeRing.init(*this);
- Ring outerAARing;
- this->createOuterRing(outerStrokeRing, kAntialiasingRadius * 2, 0.0f, &outerAARing);
- } else {
- Ring outerAARing;
- this->createOuterRing(fInitialRing, kAntialiasingRadius, 0.0f, &outerAARing);
- }
- // the bisectors are only needed for the computation of the outer ring
- fBisectors.rewind();
- if (SkStrokeRec::kStroke_Style == fStyle && fInitialRing.numPts() > 2) {
- SkASSERT(fStrokeWidth >= 0.0f);
- SkScalar effectiveStrokeWidth = scaleFactor * fStrokeWidth;
- Ring* insetStrokeRing;
- SkScalar strokeDepth = effectiveStrokeWidth / 2 - kAntialiasingRadius;
- if (this->createInsetRings(fInitialRing, 0.0f, coverage, strokeDepth, coverage,
- &insetStrokeRing)) {
- Ring* insetAARing;
- this->createInsetRings(*insetStrokeRing, strokeDepth, coverage, strokeDepth +
- kAntialiasingRadius * 2, 0.0f, &insetAARing);
- }
- } else {
- Ring* insetAARing;
- this->createInsetRings(fInitialRing, 0.0f, 0.5f, kAntialiasingRadius, 1.0f, &insetAARing);
- }
- SkDEBUGCODE(this->validate();)
- return true;
- }
- SkScalar GrAAConvexTessellator::computeDepthFromEdge(int edgeIdx, const SkPoint& p) const {
- SkASSERT(edgeIdx < fNorms.count());
- SkPoint v = p - fPts[edgeIdx];
- SkScalar depth = -fNorms[edgeIdx].dot(v);
- return depth;
- }
- // Find a point that is 'desiredDepth' away from the 'edgeIdx'-th edge and lies
- // along the 'bisector' from the 'startIdx'-th point.
- bool GrAAConvexTessellator::computePtAlongBisector(int startIdx,
- const SkVector& bisector,
- int edgeIdx,
- SkScalar desiredDepth,
- SkPoint* result) const {
- const SkPoint& norm = fNorms[edgeIdx];
- // First find the point where the edge and the bisector intersect
- SkPoint newP;
- SkScalar t = perp_intersect(fPts[startIdx], bisector, fPts[edgeIdx], norm);
- if (SkScalarNearlyEqual(t, 0.0f)) {
- // the start point was one of the original ring points
- SkASSERT(startIdx < fPts.count());
- newP = fPts[startIdx];
- } else if (t < 0.0f) {
- newP = bisector;
- newP.scale(t);
- newP += fPts[startIdx];
- } else {
- return false;
- }
- // Then offset along the bisector from that point the correct distance
- SkScalar dot = bisector.dot(norm);
- t = -desiredDepth / dot;
- *result = bisector;
- result->scale(t);
- *result += newP;
- return true;
- }
- bool GrAAConvexTessellator::extractFromPath(const SkMatrix& m, const SkPath& path) {
- SkASSERT(SkPath::kConvex_Convexity == path.getConvexity());
- SkRect bounds = path.getBounds();
- m.mapRect(&bounds);
- if (!bounds.isFinite()) {
- // We could do something smarter here like clip the path based on the bounds of the dst.
- // We'd have to be careful about strokes to ensure we don't draw something wrong.
- return false;
- }
- // Outer ring: 3*numPts
- // Middle ring: numPts
- // Presumptive inner ring: numPts
- this->reservePts(5*path.countPoints());
- // Outer ring: 12*numPts
- // Middle ring: 0
- // Presumptive inner ring: 6*numPts + 6
- fIndices.setReserve(18*path.countPoints() + 6);
- // TODO: is there a faster way to extract the points from the path? Perhaps
- // get all the points via a new entry point, transform them all in bulk
- // and then walk them to find duplicates?
- SkPath::Iter iter(path, true);
- SkPoint pts[4];
- SkPath::Verb verb;
- while ((verb = iter.next(pts, true, true)) != SkPath::kDone_Verb) {
- switch (verb) {
- case SkPath::kLine_Verb:
- this->lineTo(m, pts[1], kSharp_CurveState);
- break;
- case SkPath::kQuad_Verb:
- this->quadTo(m, pts);
- break;
- case SkPath::kCubic_Verb:
- this->cubicTo(m, pts);
- break;
- case SkPath::kConic_Verb:
- this->conicTo(m, pts, iter.conicWeight());
- break;
- case SkPath::kMove_Verb:
- case SkPath::kClose_Verb:
- case SkPath::kDone_Verb:
- break;
- }
- }
- if (this->numPts() < 2) {
- return false;
- }
- // check if last point is a duplicate of the first point. If so, remove it.
- if (duplicate_pt(fPts[this->numPts()-1], fPts[0])) {
- this->popLastPt();
- }
- // Remove any lingering colinear points where the path wraps around
- bool noRemovalsToDo = false;
- while (!noRemovalsToDo && this->numPts() >= 3) {
- if (points_are_colinear_and_b_is_middle(fPts[fPts.count() - 2], fPts.top(), fPts[0])) {
- this->popLastPt();
- } else if (points_are_colinear_and_b_is_middle(fPts.top(), fPts[0], fPts[1])) {
- this->popFirstPtShuffle();
- } else {
- noRemovalsToDo = true;
- }
- }
- // Compute the normals and bisectors.
- SkASSERT(fNorms.empty());
- if (this->numPts() >= 3) {
- this->computeNormals();
- this->computeBisectors();
- } else if (this->numPts() == 2) {
- // We've got two points, so we're degenerate.
- if (fStyle == SkStrokeRec::kFill_Style) {
- // it's a fill, so we don't need to worry about degenerate paths
- return false;
- }
- // For stroking, we still need to process the degenerate path, so fix it up
- fSide = SkPointPriv::kLeft_Side;
- fNorms.append(2);
- fNorms[0] = SkPointPriv::MakeOrthog(fPts[1] - fPts[0], fSide);
- fNorms[0].normalize();
- fNorms[1] = -fNorms[0];
- SkASSERT(SkScalarNearlyEqual(1.0f, fNorms[0].length()));
- // we won't actually use the bisectors, so just push zeroes
- fBisectors.push_back(SkPoint::Make(0.0, 0.0));
- fBisectors.push_back(SkPoint::Make(0.0, 0.0));
- } else {
- return false;
- }
- fCandidateVerts.setReserve(this->numPts());
- fInitialRing.setReserve(this->numPts());
- for (int i = 0; i < this->numPts(); ++i) {
- fInitialRing.addIdx(i, i);
- }
- fInitialRing.init(fNorms, fBisectors);
- this->validate();
- return true;
- }
- GrAAConvexTessellator::Ring* GrAAConvexTessellator::getNextRing(Ring* lastRing) {
- #if GR_AA_CONVEX_TESSELLATOR_VIZ
- Ring* ring = *fRings.push() = new Ring;
- ring->setReserve(fInitialRing.numPts());
- ring->rewind();
- return ring;
- #else
- // Flip flop back and forth between fRings[0] & fRings[1]
- int nextRing = (lastRing == &fRings[0]) ? 1 : 0;
- fRings[nextRing].setReserve(fInitialRing.numPts());
- fRings[nextRing].rewind();
- return &fRings[nextRing];
- #endif
- }
- void GrAAConvexTessellator::fanRing(const Ring& ring) {
- // fan out from point 0
- int startIdx = ring.index(0);
- for (int cur = ring.numPts() - 2; cur >= 0; --cur) {
- this->addTri(startIdx, ring.index(cur), ring.index(cur + 1));
- }
- }
- void GrAAConvexTessellator::createOuterRing(const Ring& previousRing, SkScalar outset,
- SkScalar coverage, Ring* nextRing) {
- const int numPts = previousRing.numPts();
- if (numPts == 0) {
- return;
- }
- int prev = numPts - 1;
- int lastPerpIdx = -1, firstPerpIdx = -1;
- const SkScalar outsetSq = outset * outset;
- SkScalar miterLimitSq = outset * fMiterLimit;
- miterLimitSq = miterLimitSq * miterLimitSq;
- for (int cur = 0; cur < numPts; ++cur) {
- int originalIdx = previousRing.index(cur);
- // For each vertex of the original polygon we add at least two points to the
- // outset polygon - one extending perpendicular to each impinging edge. Connecting these
- // two points yields a bevel join. We need one additional point for a mitered join, and
- // a round join requires one or more points depending upon curvature.
- // The perpendicular point for the last edge
- SkPoint normal1 = previousRing.norm(prev);
- SkPoint perp1 = normal1;
- perp1.scale(outset);
- perp1 += this->point(originalIdx);
- // The perpendicular point for the next edge.
- SkPoint normal2 = previousRing.norm(cur);
- SkPoint perp2 = normal2;
- perp2.scale(outset);
- perp2 += fPts[originalIdx];
- CurveState curve = fCurveState[originalIdx];
- // We know it isn't a duplicate of the prior point (since it and this
- // one are just perpendicular offsets from the non-merged polygon points)
- int perp1Idx = this->addPt(perp1, -outset, coverage, false, curve);
- nextRing->addIdx(perp1Idx, originalIdx);
- int perp2Idx;
- // For very shallow angles all the corner points could fuse.
- if (duplicate_pt(perp2, this->point(perp1Idx))) {
- perp2Idx = perp1Idx;
- } else {
- perp2Idx = this->addPt(perp2, -outset, coverage, false, curve);
- }
- if (perp2Idx != perp1Idx) {
- if (curve == kCurve_CurveState) {
- // bevel or round depending upon curvature
- SkScalar dotProd = normal1.dot(normal2);
- if (dotProd < kRoundCapThreshold) {
- // Currently we "round" by creating a single extra point, which produces
- // good results for common cases. For thick strokes with high curvature, we will
- // need to add more points; for the time being we simply fall back to software
- // rendering for thick strokes.
- SkPoint miter = previousRing.bisector(cur);
- miter.setLength(-outset);
- miter += fPts[originalIdx];
- // For very shallow angles all the corner points could fuse
- if (!duplicate_pt(miter, this->point(perp1Idx))) {
- int miterIdx;
- miterIdx = this->addPt(miter, -outset, coverage, false, kSharp_CurveState);
- nextRing->addIdx(miterIdx, originalIdx);
- // The two triangles for the corner
- this->addTri(originalIdx, perp1Idx, miterIdx);
- this->addTri(originalIdx, miterIdx, perp2Idx);
- }
- } else {
- this->addTri(originalIdx, perp1Idx, perp2Idx);
- }
- } else {
- switch (fJoin) {
- case SkPaint::Join::kMiter_Join: {
- // The bisector outset point
- SkPoint miter = previousRing.bisector(cur);
- SkScalar dotProd = normal1.dot(normal2);
- // The max is because this could go slightly negative if precision causes
- // us to become slightly concave.
- SkScalar sinHalfAngleSq = SkTMax(SkScalarHalf(SK_Scalar1 + dotProd), 0.f);
- SkScalar lengthSq = sk_ieee_float_divide(outsetSq, sinHalfAngleSq);
- if (lengthSq > miterLimitSq) {
- // just bevel it
- this->addTri(originalIdx, perp1Idx, perp2Idx);
- break;
- }
- miter.setLength(-SkScalarSqrt(lengthSq));
- miter += fPts[originalIdx];
- // For very shallow angles all the corner points could fuse
- if (!duplicate_pt(miter, this->point(perp1Idx))) {
- int miterIdx;
- miterIdx = this->addPt(miter, -outset, coverage, false,
- kSharp_CurveState);
- nextRing->addIdx(miterIdx, originalIdx);
- // The two triangles for the corner
- this->addTri(originalIdx, perp1Idx, miterIdx);
- this->addTri(originalIdx, miterIdx, perp2Idx);
- } else {
- // ignore the miter point as it's so close to perp1/perp2 and simply
- // bevel.
- this->addTri(originalIdx, perp1Idx, perp2Idx);
- }
- break;
- }
- case SkPaint::Join::kBevel_Join:
- this->addTri(originalIdx, perp1Idx, perp2Idx);
- break;
- default:
- // kRound_Join is unsupported for now. GrAALinearizingConvexPathRenderer is
- // only willing to draw mitered or beveled, so we should never get here.
- SkASSERT(false);
- }
- }
- nextRing->addIdx(perp2Idx, originalIdx);
- }
- if (0 == cur) {
- // Store the index of the first perpendicular point to finish up
- firstPerpIdx = perp1Idx;
- SkASSERT(-1 == lastPerpIdx);
- } else {
- // The triangles for the previous edge
- int prevIdx = previousRing.index(prev);
- this->addTri(prevIdx, perp1Idx, originalIdx);
- this->addTri(prevIdx, lastPerpIdx, perp1Idx);
- }
- // Track the last perpendicular outset point so we can construct the
- // trailing edge triangles.
- lastPerpIdx = perp2Idx;
- prev = cur;
- }
- // pick up the final edge rect
- int lastIdx = previousRing.index(numPts - 1);
- this->addTri(lastIdx, firstPerpIdx, previousRing.index(0));
- this->addTri(lastIdx, lastPerpIdx, firstPerpIdx);
- this->validate();
- }
- // Something went wrong in the creation of the next ring. If we're filling the shape, just go ahead
- // and fan it.
- void GrAAConvexTessellator::terminate(const Ring& ring) {
- if (fStyle != SkStrokeRec::kStroke_Style && ring.numPts() > 0) {
- this->fanRing(ring);
- }
- }
- static SkScalar compute_coverage(SkScalar depth, SkScalar initialDepth, SkScalar initialCoverage,
- SkScalar targetDepth, SkScalar targetCoverage) {
- if (SkScalarNearlyEqual(initialDepth, targetDepth)) {
- return targetCoverage;
- }
- SkScalar result = (depth - initialDepth) / (targetDepth - initialDepth) *
- (targetCoverage - initialCoverage) + initialCoverage;
- return SkScalarClampMax(result, 1.0f);
- }
- // return true when processing is complete
- bool GrAAConvexTessellator::createInsetRing(const Ring& lastRing, Ring* nextRing,
- SkScalar initialDepth, SkScalar initialCoverage,
- SkScalar targetDepth, SkScalar targetCoverage,
- bool forceNew) {
- bool done = false;
- fCandidateVerts.rewind();
- // Loop through all the points in the ring and find the intersection with the smallest depth
- SkScalar minDist = SK_ScalarMax, minT = 0.0f;
- int minEdgeIdx = -1;
- for (int cur = 0; cur < lastRing.numPts(); ++cur) {
- int next = (cur + 1) % lastRing.numPts();
- SkScalar t;
- bool result = intersect(this->point(lastRing.index(cur)), lastRing.bisector(cur),
- this->point(lastRing.index(next)), lastRing.bisector(next),
- &t);
- // The bisectors may be parallel (!result) or the previous ring may have become slightly
- // concave due to accumulated error (t <= 0).
- if (!result || t <= 0) {
- continue;
- }
- SkScalar dist = -t * lastRing.norm(cur).dot(lastRing.bisector(cur));
- if (minDist > dist) {
- minDist = dist;
- minT = t;
- minEdgeIdx = cur;
- }
- }
- if (minEdgeIdx == -1) {
- return false;
- }
- SkPoint newPt = lastRing.bisector(minEdgeIdx);
- newPt.scale(minT);
- newPt += this->point(lastRing.index(minEdgeIdx));
- SkScalar depth = this->computeDepthFromEdge(lastRing.origEdgeID(minEdgeIdx), newPt);
- if (depth >= targetDepth) {
- // None of the bisectors intersect before reaching the desired depth.
- // Just step them all to the desired depth
- depth = targetDepth;
- done = true;
- }
- // 'dst' stores where each point in the last ring maps to/transforms into
- // in the next ring.
- SkTDArray<int> dst;
- dst.setCount(lastRing.numPts());
- // Create the first point (who compares with no one)
- if (!this->computePtAlongBisector(lastRing.index(0),
- lastRing.bisector(0),
- lastRing.origEdgeID(0),
- depth, &newPt)) {
- this->terminate(lastRing);
- return true;
- }
- dst[0] = fCandidateVerts.addNewPt(newPt,
- lastRing.index(0), lastRing.origEdgeID(0),
- !this->movable(lastRing.index(0)));
- // Handle the middle points (who only compare with the prior point)
- for (int cur = 1; cur < lastRing.numPts()-1; ++cur) {
- if (!this->computePtAlongBisector(lastRing.index(cur),
- lastRing.bisector(cur),
- lastRing.origEdgeID(cur),
- depth, &newPt)) {
- this->terminate(lastRing);
- return true;
- }
- if (!duplicate_pt(newPt, fCandidateVerts.lastPoint())) {
- dst[cur] = fCandidateVerts.addNewPt(newPt,
- lastRing.index(cur), lastRing.origEdgeID(cur),
- !this->movable(lastRing.index(cur)));
- } else {
- dst[cur] = fCandidateVerts.fuseWithPrior(lastRing.origEdgeID(cur));
- }
- }
- // Check on the last point (handling the wrap around)
- int cur = lastRing.numPts()-1;
- if (!this->computePtAlongBisector(lastRing.index(cur),
- lastRing.bisector(cur),
- lastRing.origEdgeID(cur),
- depth, &newPt)) {
- this->terminate(lastRing);
- return true;
- }
- bool dupPrev = duplicate_pt(newPt, fCandidateVerts.lastPoint());
- bool dupNext = duplicate_pt(newPt, fCandidateVerts.firstPoint());
- if (!dupPrev && !dupNext) {
- dst[cur] = fCandidateVerts.addNewPt(newPt,
- lastRing.index(cur), lastRing.origEdgeID(cur),
- !this->movable(lastRing.index(cur)));
- } else if (dupPrev && !dupNext) {
- dst[cur] = fCandidateVerts.fuseWithPrior(lastRing.origEdgeID(cur));
- } else if (!dupPrev && dupNext) {
- dst[cur] = fCandidateVerts.fuseWithNext();
- } else {
- bool dupPrevVsNext = duplicate_pt(fCandidateVerts.firstPoint(), fCandidateVerts.lastPoint());
- if (!dupPrevVsNext) {
- dst[cur] = fCandidateVerts.fuseWithPrior(lastRing.origEdgeID(cur));
- } else {
- const int fused = fCandidateVerts.fuseWithBoth();
- dst[cur] = fused;
- const int targetIdx = dst[cur - 1];
- for (int i = cur - 1; i >= 0 && dst[i] == targetIdx; i--) {
- dst[i] = fused;
- }
- }
- }
- // Fold the new ring's points into the global pool
- for (int i = 0; i < fCandidateVerts.numPts(); ++i) {
- int newIdx;
- if (fCandidateVerts.needsToBeNew(i) || forceNew) {
- // if the originating index is still valid then this point wasn't
- // fused (and is thus movable)
- SkScalar coverage = compute_coverage(depth, initialDepth, initialCoverage,
- targetDepth, targetCoverage);
- newIdx = this->addPt(fCandidateVerts.point(i), depth, coverage,
- fCandidateVerts.originatingIdx(i) != -1, kSharp_CurveState);
- } else {
- SkASSERT(fCandidateVerts.originatingIdx(i) != -1);
- this->updatePt(fCandidateVerts.originatingIdx(i), fCandidateVerts.point(i), depth,
- targetCoverage);
- newIdx = fCandidateVerts.originatingIdx(i);
- }
- nextRing->addIdx(newIdx, fCandidateVerts.origEdge(i));
- }
- // 'dst' currently has indices into the ring. Remap these to be indices
- // into the global pool since the triangulation operates in that space.
- for (int i = 0; i < dst.count(); ++i) {
- dst[i] = nextRing->index(dst[i]);
- }
- for (int i = 0; i < lastRing.numPts(); ++i) {
- int next = (i + 1) % lastRing.numPts();
- this->addTri(lastRing.index(i), lastRing.index(next), dst[next]);
- this->addTri(lastRing.index(i), dst[next], dst[i]);
- }
- if (done && fStyle != SkStrokeRec::kStroke_Style) {
- // fill or stroke-and-fill
- this->fanRing(*nextRing);
- }
- if (nextRing->numPts() < 3) {
- done = true;
- }
- return done;
- }
- void GrAAConvexTessellator::validate() const {
- SkASSERT(fPts.count() == fMovable.count());
- SkASSERT(fPts.count() == fCoverages.count());
- SkASSERT(fPts.count() == fCurveState.count());
- SkASSERT(0 == (fIndices.count() % 3));
- SkASSERT(!fBisectors.count() || fBisectors.count() == fNorms.count());
- }
- //////////////////////////////////////////////////////////////////////////////
- void GrAAConvexTessellator::Ring::init(const GrAAConvexTessellator& tess) {
- this->computeNormals(tess);
- this->computeBisectors(tess);
- }
- void GrAAConvexTessellator::Ring::init(const SkTDArray<SkVector>& norms,
- const SkTDArray<SkVector>& bisectors) {
- for (int i = 0; i < fPts.count(); ++i) {
- fPts[i].fNorm = norms[i];
- fPts[i].fBisector = bisectors[i];
- }
- }
- // Compute the outward facing normal at each vertex.
- void GrAAConvexTessellator::Ring::computeNormals(const GrAAConvexTessellator& tess) {
- for (int cur = 0; cur < fPts.count(); ++cur) {
- int next = (cur + 1) % fPts.count();
- fPts[cur].fNorm = tess.point(fPts[next].fIndex) - tess.point(fPts[cur].fIndex);
- SkPoint::Normalize(&fPts[cur].fNorm);
- fPts[cur].fNorm = SkPointPriv::MakeOrthog(fPts[cur].fNorm, tess.side());
- }
- }
- void GrAAConvexTessellator::Ring::computeBisectors(const GrAAConvexTessellator& tess) {
- int prev = fPts.count() - 1;
- for (int cur = 0; cur < fPts.count(); prev = cur, ++cur) {
- fPts[cur].fBisector = fPts[cur].fNorm + fPts[prev].fNorm;
- if (!fPts[cur].fBisector.normalize()) {
- fPts[cur].fBisector =
- SkPointPriv::MakeOrthog(fPts[cur].fNorm, (SkPointPriv::Side)-tess.side()) +
- SkPointPriv::MakeOrthog(fPts[prev].fNorm, tess.side());
- SkAssertResult(fPts[cur].fBisector.normalize());
- } else {
- fPts[cur].fBisector.negate(); // make the bisector face in
- }
- }
- }
- //////////////////////////////////////////////////////////////////////////////
- #ifdef SK_DEBUG
- // Is this ring convex?
- bool GrAAConvexTessellator::Ring::isConvex(const GrAAConvexTessellator& tess) const {
- if (fPts.count() < 3) {
- return true;
- }
- SkPoint prev = tess.point(fPts[0].fIndex) - tess.point(fPts.top().fIndex);
- SkPoint cur = tess.point(fPts[1].fIndex) - tess.point(fPts[0].fIndex);
- SkScalar minDot = prev.fX * cur.fY - prev.fY * cur.fX;
- SkScalar maxDot = minDot;
- prev = cur;
- for (int i = 1; i < fPts.count(); ++i) {
- int next = (i + 1) % fPts.count();
- cur = tess.point(fPts[next].fIndex) - tess.point(fPts[i].fIndex);
- SkScalar dot = prev.fX * cur.fY - prev.fY * cur.fX;
- minDot = SkMinScalar(minDot, dot);
- maxDot = SkMaxScalar(maxDot, dot);
- prev = cur;
- }
- if (SkScalarNearlyEqual(maxDot, 0.0f, 0.005f)) {
- maxDot = 0;
- }
- if (SkScalarNearlyEqual(minDot, 0.0f, 0.005f)) {
- minDot = 0;
- }
- return (maxDot >= 0.0f) == (minDot >= 0.0f);
- }
- #endif
- void GrAAConvexTessellator::lineTo(const SkPoint& p, CurveState curve) {
- if (this->numPts() > 0 && duplicate_pt(p, this->lastPoint())) {
- return;
- }
- if (this->numPts() >= 2 &&
- points_are_colinear_and_b_is_middle(fPts[fPts.count() - 2], fPts.top(), p)) {
- // The old last point is on the line from the second to last to the new point
- this->popLastPt();
- // double-check that the new last point is not a duplicate of the new point. In an ideal
- // world this wouldn't be necessary (since it's only possible for non-convex paths), but
- // floating point precision issues mean it can actually happen on paths that were
- // determined to be convex.
- if (duplicate_pt(p, this->lastPoint())) {
- return;
- }
- }
- SkScalar initialRingCoverage = (SkStrokeRec::kFill_Style == fStyle) ? 0.5f : 1.0f;
- this->addPt(p, 0.0f, initialRingCoverage, false, curve);
- }
- void GrAAConvexTessellator::lineTo(const SkMatrix& m, SkPoint p, CurveState curve) {
- m.mapPoints(&p, 1);
- this->lineTo(p, curve);
- }
- void GrAAConvexTessellator::quadTo(const SkPoint pts[3]) {
- int maxCount = GrPathUtils::quadraticPointCount(pts, kQuadTolerance);
- fPointBuffer.setCount(maxCount);
- SkPoint* target = fPointBuffer.begin();
- int count = GrPathUtils::generateQuadraticPoints(pts[0], pts[1], pts[2],
- kQuadTolerance, &target, maxCount);
- fPointBuffer.setCount(count);
- for (int i = 0; i < count - 1; i++) {
- this->lineTo(fPointBuffer[i], kCurve_CurveState);
- }
- this->lineTo(fPointBuffer[count - 1], kIndeterminate_CurveState);
- }
- void GrAAConvexTessellator::quadTo(const SkMatrix& m, SkPoint pts[3]) {
- m.mapPoints(pts, 3);
- this->quadTo(pts);
- }
- void GrAAConvexTessellator::cubicTo(const SkMatrix& m, SkPoint pts[4]) {
- m.mapPoints(pts, 4);
- int maxCount = GrPathUtils::cubicPointCount(pts, kCubicTolerance);
- fPointBuffer.setCount(maxCount);
- SkPoint* target = fPointBuffer.begin();
- int count = GrPathUtils::generateCubicPoints(pts[0], pts[1], pts[2], pts[3],
- kCubicTolerance, &target, maxCount);
- fPointBuffer.setCount(count);
- for (int i = 0; i < count - 1; i++) {
- this->lineTo(fPointBuffer[i], kCurve_CurveState);
- }
- this->lineTo(fPointBuffer[count - 1], kIndeterminate_CurveState);
- }
- // include down here to avoid compilation errors caused by "-" overload in SkGeometry.h
- #include "src/core/SkGeometry.h"
- void GrAAConvexTessellator::conicTo(const SkMatrix& m, SkPoint pts[3], SkScalar w) {
- m.mapPoints(pts, 3);
- SkAutoConicToQuads quadder;
- const SkPoint* quads = quadder.computeQuads(pts, w, kConicTolerance);
- SkPoint lastPoint = *(quads++);
- int count = quadder.countQuads();
- for (int i = 0; i < count; ++i) {
- SkPoint quadPts[3];
- quadPts[0] = lastPoint;
- quadPts[1] = quads[0];
- quadPts[2] = i == count - 1 ? pts[2] : quads[1];
- this->quadTo(quadPts);
- lastPoint = quadPts[2];
- quads += 2;
- }
- }
- //////////////////////////////////////////////////////////////////////////////
- #if GR_AA_CONVEX_TESSELLATOR_VIZ
- static const SkScalar kPointRadius = 0.02f;
- static const SkScalar kArrowStrokeWidth = 0.0f;
- static const SkScalar kArrowLength = 0.2f;
- static const SkScalar kEdgeTextSize = 0.1f;
- static const SkScalar kPointTextSize = 0.02f;
- static void draw_point(SkCanvas* canvas, const SkPoint& p, SkScalar paramValue, bool stroke) {
- SkPaint paint;
- SkASSERT(paramValue <= 1.0f);
- int gs = int(255*paramValue);
- paint.setARGB(255, gs, gs, gs);
- canvas->drawCircle(p.fX, p.fY, kPointRadius, paint);
- if (stroke) {
- SkPaint stroke;
- stroke.setColor(SK_ColorYELLOW);
- stroke.setStyle(SkPaint::kStroke_Style);
- stroke.setStrokeWidth(kPointRadius/3.0f);
- canvas->drawCircle(p.fX, p.fY, kPointRadius, stroke);
- }
- }
- static void draw_line(SkCanvas* canvas, const SkPoint& p0, const SkPoint& p1, SkColor color) {
- SkPaint p;
- p.setColor(color);
- canvas->drawLine(p0.fX, p0.fY, p1.fX, p1.fY, p);
- }
- static void draw_arrow(SkCanvas*canvas, const SkPoint& p, const SkPoint &n,
- SkScalar len, SkColor color) {
- SkPaint paint;
- paint.setColor(color);
- paint.setStrokeWidth(kArrowStrokeWidth);
- paint.setStyle(SkPaint::kStroke_Style);
- canvas->drawLine(p.fX, p.fY,
- p.fX + len * n.fX, p.fY + len * n.fY,
- paint);
- }
- void GrAAConvexTessellator::Ring::draw(SkCanvas* canvas, const GrAAConvexTessellator& tess) const {
- SkPaint paint;
- paint.setTextSize(kEdgeTextSize);
- for (int cur = 0; cur < fPts.count(); ++cur) {
- int next = (cur + 1) % fPts.count();
- draw_line(canvas,
- tess.point(fPts[cur].fIndex),
- tess.point(fPts[next].fIndex),
- SK_ColorGREEN);
- SkPoint mid = tess.point(fPts[cur].fIndex) + tess.point(fPts[next].fIndex);
- mid.scale(0.5f);
- if (fPts.count()) {
- draw_arrow(canvas, mid, fPts[cur].fNorm, kArrowLength, SK_ColorRED);
- mid.fX += (kArrowLength/2) * fPts[cur].fNorm.fX;
- mid.fY += (kArrowLength/2) * fPts[cur].fNorm.fY;
- }
- SkString num;
- num.printf("%d", this->origEdgeID(cur));
- canvas->drawString(num, mid.fX, mid.fY, paint);
- if (fPts.count()) {
- draw_arrow(canvas, tess.point(fPts[cur].fIndex), fPts[cur].fBisector,
- kArrowLength, SK_ColorBLUE);
- }
- }
- }
- void GrAAConvexTessellator::draw(SkCanvas* canvas) const {
- for (int i = 0; i < fIndices.count(); i += 3) {
- SkASSERT(fIndices[i] < this->numPts()) ;
- SkASSERT(fIndices[i+1] < this->numPts()) ;
- SkASSERT(fIndices[i+2] < this->numPts()) ;
- draw_line(canvas,
- this->point(this->fIndices[i]), this->point(this->fIndices[i+1]),
- SK_ColorBLACK);
- draw_line(canvas,
- this->point(this->fIndices[i+1]), this->point(this->fIndices[i+2]),
- SK_ColorBLACK);
- draw_line(canvas,
- this->point(this->fIndices[i+2]), this->point(this->fIndices[i]),
- SK_ColorBLACK);
- }
- fInitialRing.draw(canvas, *this);
- for (int i = 0; i < fRings.count(); ++i) {
- fRings[i]->draw(canvas, *this);
- }
- for (int i = 0; i < this->numPts(); ++i) {
- draw_point(canvas,
- this->point(i), 0.5f + (this->depth(i)/(2 * kAntialiasingRadius)),
- !this->movable(i));
- SkPaint paint;
- paint.setTextSize(kPointTextSize);
- if (this->depth(i) <= -kAntialiasingRadius) {
- paint.setColor(SK_ColorWHITE);
- }
- SkString num;
- num.printf("%d", i);
- canvas->drawString(num,
- this->point(i).fX, this->point(i).fY+(kPointRadius/2.0f),
- paint);
- }
- }
- #endif
|