| /* |
| * 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 "GrAAConvexTessellator.h" |
| #include "SkCanvas.h" |
| #include "SkPath.h" |
| #include "SkPoint.h" |
| #include "SkString.h" |
| #include "GrPathUtils.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 = SkScalarMul(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 = 0.5f; |
| |
| // 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 = p0.distanceToSqd(p1); |
| return distSq < kCloseSqd; |
| } |
| |
| static SkScalar abs_dist_from_line(const SkPoint& p0, const SkVector& v, const SkPoint& test) { |
| SkPoint testV = test - p0; |
| SkScalar dist = testV.fX * v.fY - testV.fY * v.fX; |
| return SkScalarAbs(dist); |
| } |
| |
| int GrAAConvexTessellator::addPt(const SkPoint& pt, |
| SkScalar depth, |
| SkScalar coverage, |
| bool movable, |
| CurveState curve) { |
| 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::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()) { |
| SkASSERT(SkPoint::kLeft_Side == fSide || SkPoint::kRight_Side == fSide); |
| fBisectors[cur].setOrthog(fNorms[cur], (SkPoint::Side)-fSide); |
| SkVector other; |
| other.setOrthog(fNorms[prev], fSide); |
| fBisectors[cur] += other; |
| 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()); |
| |
| // 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); |
| |
| fNorms.setReserve(path.countPoints()); |
| |
| // 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)) != 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(); |
| fNorms.pop(); |
| } |
| |
| SkASSERT(fPts.count() == fNorms.count()+1); |
| if (this->numPts() >= 3) { |
| if (abs_dist_from_line(fPts.top(), fNorms.top(), fPts[0]) < kClose) { |
| // The last point is on the line from the second to last to the first point. |
| this->popLastPt(); |
| fNorms.pop(); |
| } |
| |
| *fNorms.push() = fPts[0] - fPts.top(); |
| SkDEBUGCODE(SkScalar len =) SkPoint::Normalize(&fNorms.top()); |
| SkASSERT(len > 0.0f); |
| SkASSERT(fPts.count() == fNorms.count()); |
| } |
| |
| if (this->numPts() >= 3 && abs_dist_from_line(fPts[0], fNorms.top(), fPts[1]) < kClose) { |
| // The first point is on the line from the last to the second. |
| this->popFirstPtShuffle(); |
| fNorms.removeShuffle(0); |
| fNorms[0] = fPts[1] - fPts[0]; |
| SkDEBUGCODE(SkScalar len =) SkPoint::Normalize(&fNorms[0]); |
| SkASSERT(len > 0.0f); |
| SkASSERT(SkScalarNearlyEqual(1.0f, fNorms[0].length())); |
| } |
| |
| if (this->numPts() >= 3) { |
| // Check the cross product of the final trio |
| SkScalar cross = SkPoint::CrossProduct(fNorms[0], fNorms.top()); |
| if (cross > 0.0f) { |
| fSide = SkPoint::kRight_Side; |
| } else { |
| fSide = SkPoint::kLeft_Side; |
| } |
| |
| // Make all the normals face outwards rather than along the edge |
| for (int cur = 0; cur < fNorms.count(); ++cur) { |
| fNorms[cur].setOrthog(fNorms[cur], fSide); |
| SkASSERT(SkScalarNearlyEqual(1.0f, fNorms[cur].length())); |
| } |
| |
| 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 = SkPoint::kLeft_Side; |
| |
| // Make all the normals face outwards rather than along the edge |
| for (int cur = 0; cur < fNorms.count(); ++cur) { |
| fNorms[cur].setOrthog(fNorms[cur], fSide); |
| SkASSERT(SkScalarNearlyEqual(1.0f, fNorms[cur].length())); |
| } |
| |
| fNorms.push(SkPoint::Make(-fNorms[0].fX, -fNorms[0].fY)); |
| // we won't actually use the bisectors, so just push zeroes |
| fBisectors.push(SkPoint::Make(0.0, 0.0)); |
| fBisectors.push(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 = SkScalarMul(outset, outset); |
| SkScalar miterLimitSq = SkScalarMul(outset, fMiterLimit); |
| miterLimitSq = SkScalarMul(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); |
| SkScalar sinHalfAngleSq = SkScalarHalf(SK_Scalar1 + dotProd); |
| SkScalar lengthSq = 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); |
| } |
| 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) { |
| 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); |
| if (!result) { |
| 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.setOrthog(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()) { |
| SkASSERT(SkPoint::kLeft_Side == tess.side() || SkPoint::kRight_Side == tess.side()); |
| fPts[cur].fBisector.setOrthog(fPts[cur].fNorm, (SkPoint::Side)-tess.side()); |
| SkVector other; |
| other.setOrthog(fPts[prev].fNorm, tess.side()); |
| fPts[cur].fBisector += other; |
| 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; |
| } |
| |
| SkASSERT(fPts.count() <= 1 || fPts.count() == fNorms.count()+1); |
| if (this->numPts() >= 2 && abs_dist_from_line(fPts.top(), fNorms.top(), p) < kClose) { |
| // The old last point is on the line from the second to last to the new point |
| this->popLastPt(); |
| fNorms.pop(); |
| // 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); |
| if (this->numPts() > 1) { |
| *fNorms.push() = fPts.top() - fPts[fPts.count()-2]; |
| SkDEBUGCODE(SkScalar len =) SkPoint::Normalize(&fNorms.top()); |
| SkASSERT(len > 0.0f); |
| SkASSERT(SkScalarNearlyEqual(1.0f, fNorms.top().length())); |
| } |
| } |
| |
| 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.setReserve(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.setReserve(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 "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->drawText(num.c_str(), num.size(), 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); |
| paint.setTextAlign(SkPaint::kCenter_Align); |
| if (this->depth(i) <= -kAntialiasingRadius) { |
| paint.setColor(SK_ColorWHITE); |
| } |
| |
| SkString num; |
| num.printf("%d", i); |
| canvas->drawText(num.c_str(), num.size(), |
| this->point(i).fX, this->point(i).fY+(kPointRadius/2.0f), |
| paint); |
| } |
| } |
| |
| #endif |