| /* |
| * 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 "SkShadowTessellator.h" |
| #include "SkColorPriv.h" |
| #include "SkGeometry.h" |
| #include "SkInsetConvexPolygon.h" |
| #include "SkPath.h" |
| #include "SkVertices.h" |
| |
| #if SK_SUPPORT_GPU |
| #include "GrPathUtils.h" |
| #endif |
| |
| |
| /** |
| * Base class |
| */ |
| class SkBaseShadowTessellator { |
| public: |
| SkBaseShadowTessellator(const SkPoint3& zPlaneParams, bool transparent); |
| virtual ~SkBaseShadowTessellator() {} |
| |
| sk_sp<SkVertices> releaseVertices() { |
| if (!fSucceeded) { |
| return nullptr; |
| } |
| return SkVertices::MakeCopy(SkVertices::kTriangles_VertexMode, this->vertexCount(), |
| fPositions.begin(), nullptr, fColors.begin(), |
| this->indexCount(), fIndices.begin()); |
| } |
| |
| protected: |
| static constexpr auto kMinHeight = 0.1f; |
| |
| int vertexCount() const { return fPositions.count(); } |
| int indexCount() const { return fIndices.count(); } |
| |
| bool setZOffset(const SkRect& bounds, bool perspective); |
| |
| virtual void handleLine(const SkPoint& p) = 0; |
| void handleLine(const SkMatrix& m, SkPoint* p); |
| |
| void handleQuad(const SkPoint pts[3]); |
| void handleQuad(const SkMatrix& m, SkPoint pts[3]); |
| |
| void handleCubic(const SkMatrix& m, SkPoint pts[4]); |
| |
| void handleConic(const SkMatrix& m, SkPoint pts[3], SkScalar w); |
| |
| bool setTransformedHeightFunc(const SkMatrix& ctm); |
| |
| bool addArc(const SkVector& nextNormal, bool finishArc); |
| |
| SkScalar heightFunc(SkScalar x, SkScalar y) { |
| return fZPlaneParams.fX*x + fZPlaneParams.fY*y + fZPlaneParams.fZ; |
| } |
| |
| SkPoint3 fZPlaneParams; |
| std::function<SkScalar(const SkPoint&)> fTransformedHeightFunc; |
| SkScalar fZOffset; |
| // members for perspective height function |
| SkPoint3 fTransformedZParams; |
| SkScalar fPartialDeterminants[3]; |
| |
| // first two points |
| SkTDArray<SkPoint> fInitPoints; |
| // temporary buffer |
| SkTDArray<SkPoint> fPointBuffer; |
| |
| SkTDArray<SkPoint> fPositions; |
| SkTDArray<SkColor> fColors; |
| SkTDArray<uint16_t> fIndices; |
| |
| int fFirstVertexIndex; |
| SkVector fFirstOutset; |
| SkPoint fFirstPoint; |
| |
| bool fSucceeded; |
| bool fTransparent; |
| |
| SkColor fUmbraColor; |
| SkColor fPenumbraColor; |
| |
| SkScalar fRadius; |
| SkScalar fDirection; |
| int fPrevUmbraIndex; |
| SkVector fPrevOutset; |
| SkPoint fPrevPoint; |
| }; |
| |
| static bool compute_normal(const SkPoint& p0, const SkPoint& p1, SkScalar dir, |
| SkVector* newNormal) { |
| SkVector normal; |
| // compute perpendicular |
| normal.fX = p0.fY - p1.fY; |
| normal.fY = p1.fX - p0.fX; |
| normal *= dir; |
| if (!normal.normalize()) { |
| return false; |
| } |
| *newNormal = normal; |
| return true; |
| } |
| |
| static void compute_radial_steps(const SkVector& v1, const SkVector& v2, SkScalar r, |
| SkScalar* rotSin, SkScalar* rotCos, int* n) { |
| const SkScalar kRecipPixelsPerArcSegment = 0.125f; |
| |
| SkScalar rCos = v1.dot(v2); |
| SkScalar rSin = v1.cross(v2); |
| SkScalar theta = SkScalarATan2(rSin, rCos); |
| |
| int steps = SkScalarFloorToInt(r*theta*kRecipPixelsPerArcSegment); |
| |
| SkScalar dTheta = theta / steps; |
| *rotSin = SkScalarSinCos(dTheta, rotCos); |
| *n = steps; |
| } |
| |
| SkBaseShadowTessellator::SkBaseShadowTessellator(const SkPoint3& zPlaneParams, bool transparent) |
| : fZPlaneParams(zPlaneParams) |
| , fZOffset(0) |
| , fFirstVertexIndex(-1) |
| , fSucceeded(false) |
| , fTransparent(transparent) |
| , fDirection(1) |
| , fPrevUmbraIndex(-1) { |
| fInitPoints.setReserve(3); |
| |
| // child classes will set reserve for positions, colors and indices |
| } |
| |
| bool SkBaseShadowTessellator::setZOffset(const SkRect& bounds, bool perspective) { |
| SkScalar minZ = this->heightFunc(bounds.fLeft, bounds.fTop); |
| if (perspective) { |
| SkScalar z = this->heightFunc(bounds.fLeft, bounds.fBottom); |
| if (z < minZ) { |
| minZ = z; |
| } |
| z = this->heightFunc(bounds.fRight, bounds.fTop); |
| if (z < minZ) { |
| minZ = z; |
| } |
| z = this->heightFunc(bounds.fRight, bounds.fBottom); |
| if (z < minZ) { |
| minZ = z; |
| } |
| } |
| |
| if (minZ < kMinHeight) { |
| fZOffset = -minZ + kMinHeight; |
| return true; |
| } |
| |
| return false; |
| } |
| |
| // tesselation tolerance values, in device space pixels |
| #if SK_SUPPORT_GPU |
| static const SkScalar kQuadTolerance = 0.2f; |
| static const SkScalar kCubicTolerance = 0.2f; |
| #endif |
| static const SkScalar kConicTolerance = 0.5f; |
| |
| void SkBaseShadowTessellator::handleLine(const SkMatrix& m, SkPoint* p) { |
| m.mapPoints(p, 1); |
| this->handleLine(*p); |
| } |
| |
| void SkBaseShadowTessellator::handleQuad(const SkPoint pts[3]) { |
| #if SK_SUPPORT_GPU |
| // TODO: Pull PathUtils out of Ganesh? |
| 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; i++) { |
| this->handleLine(fPointBuffer[i]); |
| } |
| #else |
| // for now, just to draw something |
| this->handleLine(pts[1]); |
| this->handleLine(pts[2]); |
| #endif |
| } |
| |
| void SkBaseShadowTessellator::handleQuad(const SkMatrix& m, SkPoint pts[3]) { |
| m.mapPoints(pts, 3); |
| this->handleQuad(pts); |
| } |
| |
| void SkBaseShadowTessellator::handleCubic(const SkMatrix& m, SkPoint pts[4]) { |
| m.mapPoints(pts, 4); |
| #if SK_SUPPORT_GPU |
| // TODO: Pull PathUtils out of Ganesh? |
| 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; i++) { |
| this->handleLine(fPointBuffer[i]); |
| } |
| #else |
| // for now, just to draw something |
| this->handleLine(pts[1]); |
| this->handleLine(pts[2]); |
| this->handleLine(pts[3]); |
| #endif |
| } |
| |
| void SkBaseShadowTessellator::handleConic(const SkMatrix& m, SkPoint pts[3], SkScalar w) { |
| if (m.hasPerspective()) { |
| w = SkConic::TransformW(pts, w, m); |
| } |
| 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->handleQuad(quadPts); |
| lastPoint = quadPts[2]; |
| quads += 2; |
| } |
| } |
| |
| bool SkBaseShadowTessellator::addArc(const SkVector& nextNormal, bool finishArc) { |
| // fill in fan from previous quad |
| SkScalar rotSin, rotCos; |
| int numSteps; |
| compute_radial_steps(fPrevOutset, nextNormal, fRadius, &rotSin, &rotCos, &numSteps); |
| SkVector prevNormal = fPrevOutset; |
| for (int i = 0; i < numSteps-1; ++i) { |
| SkVector currNormal; |
| currNormal.fX = prevNormal.fX*rotCos - prevNormal.fY*rotSin; |
| currNormal.fY = prevNormal.fY*rotCos + prevNormal.fX*rotSin; |
| *fPositions.push() = fPrevPoint + currNormal; |
| *fColors.push() = fPenumbraColor; |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fPositions.count() - 2; |
| |
| prevNormal = currNormal; |
| } |
| if (finishArc && numSteps) { |
| *fPositions.push() = fPrevPoint + nextNormal; |
| *fColors.push() = fPenumbraColor; |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fPositions.count() - 2; |
| } |
| fPrevOutset = nextNormal; |
| |
| return (numSteps > 0); |
| } |
| |
| bool SkBaseShadowTessellator::setTransformedHeightFunc(const SkMatrix& ctm) { |
| if (SkScalarNearlyZero(fZPlaneParams.fX) && SkScalarNearlyZero(fZPlaneParams.fY)) { |
| fTransformedHeightFunc = [this](const SkPoint& p) { |
| return fZPlaneParams.fZ; |
| }; |
| } else { |
| SkMatrix ctmInverse; |
| if (!ctm.invert(&ctmInverse)) { |
| return false; |
| } |
| // multiply by transpose |
| fTransformedZParams = SkPoint3::Make( |
| ctmInverse[SkMatrix::kMScaleX] * fZPlaneParams.fX + |
| ctmInverse[SkMatrix::kMSkewY] * fZPlaneParams.fY + |
| ctmInverse[SkMatrix::kMPersp0] * fZPlaneParams.fZ, |
| |
| ctmInverse[SkMatrix::kMSkewX] * fZPlaneParams.fX + |
| ctmInverse[SkMatrix::kMScaleY] * fZPlaneParams.fY + |
| ctmInverse[SkMatrix::kMPersp1] * fZPlaneParams.fZ, |
| |
| ctmInverse[SkMatrix::kMTransX] * fZPlaneParams.fX + |
| ctmInverse[SkMatrix::kMTransY] * fZPlaneParams.fY + |
| ctmInverse[SkMatrix::kMPersp2] * fZPlaneParams.fZ |
| ); |
| |
| if (ctm.hasPerspective()) { |
| // We use Cramer's rule to solve for the W value for a given post-divide X and Y, |
| // so pre-compute those values that are independent of X and Y. |
| // W is det(ctmInverse)/(PD[0]*X + PD[1]*Y + PD[2]) |
| fPartialDeterminants[0] = ctm[SkMatrix::kMSkewY] * ctm[SkMatrix::kMPersp1] - |
| ctm[SkMatrix::kMScaleY] * ctm[SkMatrix::kMPersp0]; |
| fPartialDeterminants[1] = ctm[SkMatrix::kMPersp0] * ctm[SkMatrix::kMSkewX] - |
| ctm[SkMatrix::kMPersp1] * ctm[SkMatrix::kMScaleX]; |
| fPartialDeterminants[2] = ctm[SkMatrix::kMScaleX] * ctm[SkMatrix::kMScaleY] - |
| ctm[SkMatrix::kMSkewX] * ctm[SkMatrix::kMSkewY]; |
| SkScalar ctmDeterminant = ctm[SkMatrix::kMTransX] * fPartialDeterminants[0] + |
| ctm[SkMatrix::kMTransY] * fPartialDeterminants[1] + |
| ctm[SkMatrix::kMPersp2] * fPartialDeterminants[2]; |
| |
| // Pre-bake the numerator of Cramer's rule into the zParams to avoid another multiply. |
| // TODO: this may introduce numerical instability, but I haven't seen any issues yet. |
| fTransformedZParams.fX *= ctmDeterminant; |
| fTransformedZParams.fY *= ctmDeterminant; |
| fTransformedZParams.fZ *= ctmDeterminant; |
| |
| fTransformedHeightFunc = [this](const SkPoint& p) { |
| SkScalar denom = p.fX * fPartialDeterminants[0] + |
| p.fY * fPartialDeterminants[1] + |
| fPartialDeterminants[2]; |
| SkScalar w = SkScalarFastInvert(denom); |
| return fZOffset + w*(fTransformedZParams.fX * p.fX + |
| fTransformedZParams.fY * p.fY + |
| fTransformedZParams.fZ); |
| }; |
| } else { |
| fTransformedHeightFunc = [this](const SkPoint& p) { |
| return fZOffset + fTransformedZParams.fX * p.fX + |
| fTransformedZParams.fY * p.fY + fTransformedZParams.fZ; |
| }; |
| } |
| } |
| |
| return true; |
| } |
| |
| |
| ////////////////////////////////////////////////////////////////////////////////////////////////// |
| |
| class SkAmbientShadowTessellator : public SkBaseShadowTessellator { |
| public: |
| SkAmbientShadowTessellator(const SkPath& path, const SkMatrix& ctm, |
| const SkPoint3& zPlaneParams, bool transparent); |
| |
| private: |
| void handleLine(const SkPoint& p) override; |
| void addEdge(const SkVector& nextPoint, const SkVector& nextNormal); |
| |
| static constexpr auto kHeightFactor = 1.0f / 128.0f; |
| static constexpr auto kGeomFactor = 64.0f; |
| static constexpr auto kMaxEdgeLenSqr = 20 * 20; |
| static constexpr auto kInsetFactor = -0.5f; |
| |
| SkScalar offset(SkScalar z) { |
| return z * kHeightFactor * kGeomFactor; |
| } |
| SkColor umbraColor(SkScalar z) { |
| SkScalar umbraAlpha = SkScalarInvert((1.0f + SkTMax(z*kHeightFactor, 0.0f))); |
| return SkColorSetARGB(umbraAlpha * 255.9999f, 0, 0, 0); |
| } |
| |
| int fCentroidCount; |
| bool fSplitFirstEdge; |
| bool fSplitPreviousEdge; |
| |
| typedef SkBaseShadowTessellator INHERITED; |
| }; |
| |
| SkAmbientShadowTessellator::SkAmbientShadowTessellator(const SkPath& path, |
| const SkMatrix& ctm, |
| const SkPoint3& zPlaneParams, |
| bool transparent) |
| : INHERITED(zPlaneParams, transparent) |
| , fSplitFirstEdge(false) |
| , fSplitPreviousEdge(false) { |
| // Set base colors |
| SkScalar occluderHeight = heightFunc(0, 0); |
| SkScalar umbraAlpha = SkScalarInvert((1.0f + SkTMax(occluderHeight*kHeightFactor, 0.0f))); |
| // umbraColor is the interior value, penumbraColor the exterior value. |
| // umbraAlpha is the factor that is linearly interpolated from outside to inside, and |
| // then "blurred" by the GrBlurredEdgeFP. It is then multiplied by fAmbientAlpha to get |
| // the final alpha. |
| fUmbraColor = SkColorSetARGB(umbraAlpha * 255.9999f, 0, 0, 0); |
| fPenumbraColor = SkColorSetARGB(0, 0, 0, 0); |
| |
| // make sure we're not below the canvas plane |
| this->setZOffset(path.getBounds(), ctm.hasPerspective()); |
| |
| this->setTransformedHeightFunc(ctm); |
| |
| // Outer ring: 3*numPts |
| // Middle ring: numPts |
| fPositions.setReserve(4 * path.countPoints()); |
| fColors.setReserve(4 * path.countPoints()); |
| // Outer ring: 12*numPts |
| // Middle ring: 0 |
| fIndices.setReserve(12 * path.countPoints()); |
| |
| // walk around the path, tessellate and generate outer ring |
| // if original path is transparent, will accumulate sum of points for centroid |
| SkPath::Iter iter(path, true); |
| SkPoint pts[4]; |
| SkPath::Verb verb; |
| if (fTransparent) { |
| *fPositions.push() = SkPoint::Make(0, 0); |
| *fColors.push() = fUmbraColor; |
| fCentroidCount = 0; |
| } |
| while ((verb = iter.next(pts)) != SkPath::kDone_Verb) { |
| switch (verb) { |
| case SkPath::kLine_Verb: |
| this->INHERITED::handleLine(ctm, &pts[1]); |
| break; |
| case SkPath::kQuad_Verb: |
| this->handleQuad(ctm, pts); |
| break; |
| case SkPath::kCubic_Verb: |
| this->handleCubic(ctm, pts); |
| break; |
| case SkPath::kConic_Verb: |
| this->handleConic(ctm, pts, iter.conicWeight()); |
| break; |
| case SkPath::kMove_Verb: |
| case SkPath::kClose_Verb: |
| case SkPath::kDone_Verb: |
| break; |
| } |
| } |
| |
| if (!this->indexCount()) { |
| return; |
| } |
| |
| // Finish up |
| SkVector normal; |
| if (compute_normal(fPrevPoint, fFirstPoint, fDirection, &normal)) { |
| SkScalar z = fTransformedHeightFunc(fPrevPoint); |
| fRadius = this->offset(z); |
| SkVector scaledNormal(normal); |
| scaledNormal *= fRadius; |
| this->addArc(scaledNormal, true); |
| |
| // fix-up the last and first umbra points |
| SkVector inset = normal; |
| // adding to an average, so multiply by an additional half |
| inset *= 0.5f*kInsetFactor; |
| fPositions[fPrevUmbraIndex] += inset; |
| fPositions[fFirstVertexIndex] += inset; |
| // we multiply by another half because now we're adding to an average of an average |
| inset *= 0.5f; |
| if (fSplitPreviousEdge) { |
| fPositions[fPrevUmbraIndex - 2] += inset; |
| } |
| if (fSplitFirstEdge) { |
| fPositions[fFirstVertexIndex + 2] += inset; |
| } |
| |
| // set up for final edge |
| z = fTransformedHeightFunc(fFirstPoint); |
| normal *= this->offset(z); |
| |
| // make sure we don't end up with a sharp alpha edge along the quad diagonal |
| if (fColors[fPrevUmbraIndex] != fColors[fFirstVertexIndex] && |
| fFirstPoint.distanceToSqd(fPositions[fPrevUmbraIndex]) > kMaxEdgeLenSqr) { |
| SkPoint centerPoint = fPositions[fPrevUmbraIndex] + fPositions[fFirstVertexIndex]; |
| centerPoint *= 0.5f; |
| *fPositions.push() = centerPoint; |
| *fColors.push() = SkPMLerp(fColors[fFirstVertexIndex], fColors[fPrevUmbraIndex], 128); |
| centerPoint = fPositions[fPositions.count()-2] + fPositions[fFirstVertexIndex+1]; |
| centerPoint *= 0.5f; |
| *fPositions.push() = centerPoint; |
| *fColors.push() = fPenumbraColor; |
| |
| if (fColors[fPrevUmbraIndex] > fColors[fPositions.count() - 2]) { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 3; |
| *fIndices.push() = fPositions.count() - 2; |
| |
| *fIndices.push() = fPositions.count() - 3; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fPositions.count() - 2; |
| } else { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 2; |
| *fIndices.push() = fPositions.count() - 1; |
| |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fPositions.count() - 3; |
| } |
| |
| // if transparent, add point to first one in array and add to center fan |
| if (fTransparent) { |
| fPositions[0] += centerPoint; |
| ++fCentroidCount; |
| |
| *fIndices.push() = 0; |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 2; |
| } |
| |
| fPrevUmbraIndex = fPositions.count() - 2; |
| } |
| |
| // final edge |
| *fPositions.push() = fFirstPoint + normal; |
| *fColors.push() = fPenumbraColor; |
| |
| if (fColors[fPrevUmbraIndex] > fColors[fFirstVertexIndex]) { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 2; |
| *fIndices.push() = fFirstVertexIndex; |
| |
| *fIndices.push() = fPositions.count() - 2; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fFirstVertexIndex; |
| } else { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 2; |
| *fIndices.push() = fPositions.count() - 1; |
| |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fFirstVertexIndex; |
| } |
| fPrevOutset = normal; |
| } |
| |
| // finalize centroid |
| if (fTransparent) { |
| fPositions[0] *= SkScalarFastInvert(fCentroidCount); |
| fColors[0] = this->umbraColor(fTransformedHeightFunc(fPositions[0])); |
| |
| *fIndices.push() = 0; |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fFirstVertexIndex; |
| } |
| |
| // final fan |
| if (fPositions.count() >= 3) { |
| fPrevUmbraIndex = fFirstVertexIndex; |
| fPrevPoint = fFirstPoint; |
| fRadius = this->offset(fTransformedHeightFunc(fPrevPoint)); |
| if (this->addArc(fFirstOutset, false)) { |
| *fIndices.push() = fFirstVertexIndex; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fFirstVertexIndex + 1; |
| } else { |
| // arc is too small, set the first penumbra point to be the same position |
| // as the last one |
| fPositions[fFirstVertexIndex + 1] = fPositions[fPositions.count() - 1]; |
| } |
| } |
| fSucceeded = true; |
| } |
| |
| void SkAmbientShadowTessellator::handleLine(const SkPoint& p) { |
| if (fInitPoints.count() < 2) { |
| *fInitPoints.push() = p; |
| return; |
| } |
| |
| if (fInitPoints.count() == 2) { |
| // determine if cw or ccw |
| SkVector v0 = fInitPoints[1] - fInitPoints[0]; |
| SkVector v1 = p - fInitPoints[0]; |
| SkScalar perpDot = v0.fX*v1.fY - v0.fY*v1.fX; |
| if (SkScalarNearlyZero(perpDot)) { |
| // nearly parallel, just treat as straight line and continue |
| fInitPoints[1] = p; |
| return; |
| } |
| |
| // if perpDot > 0, winding is ccw |
| fDirection = (perpDot > 0) ? -1 : 1; |
| |
| // add first quad |
| SkVector normal; |
| if (!compute_normal(fInitPoints[0], fInitPoints[1], fDirection, &normal)) { |
| // first two points are incident, make the third point the second and continue |
| fInitPoints[1] = p; |
| return; |
| } |
| |
| fFirstPoint = fInitPoints[0]; |
| fFirstVertexIndex = fPositions.count(); |
| SkScalar z = fTransformedHeightFunc(fFirstPoint); |
| fFirstOutset = normal; |
| fFirstOutset *= this->offset(z); |
| |
| fPrevOutset = fFirstOutset; |
| fPrevPoint = fFirstPoint; |
| fPrevUmbraIndex = fFirstVertexIndex; |
| |
| *fPositions.push() = fFirstPoint; |
| *fColors.push() = this->umbraColor(z); |
| *fPositions.push() = fFirstPoint + fFirstOutset; |
| *fColors.push() = fPenumbraColor; |
| if (fTransparent) { |
| fPositions[0] += fFirstPoint; |
| fCentroidCount = 1; |
| } |
| |
| // add the first quad |
| z = fTransformedHeightFunc(fInitPoints[1]); |
| fRadius = this->offset(z); |
| fUmbraColor = this->umbraColor(z); |
| this->addEdge(fInitPoints[1], normal); |
| |
| // to ensure we skip this block next time |
| *fInitPoints.push() = p; |
| } |
| |
| SkVector normal; |
| if (compute_normal(fPrevPoint, p, fDirection, &normal)) { |
| SkVector scaledNormal = normal; |
| scaledNormal *= fRadius; |
| this->addArc(scaledNormal, true); |
| SkScalar z = fTransformedHeightFunc(p); |
| fRadius = this->offset(z); |
| fUmbraColor = this->umbraColor(z); |
| this->addEdge(p, normal); |
| } |
| } |
| |
| void SkAmbientShadowTessellator::addEdge(const SkPoint& nextPoint, const SkVector& nextNormal) { |
| // We compute the inset in two stages: first we inset by half the current normal, |
| // then on the next addEdge() we add half of the next normal to get an average of the two |
| SkVector insetNormal = nextNormal; |
| insetNormal *= 0.5f*kInsetFactor; |
| |
| // Adding the other half of the average for the previous edge |
| fPositions[fPrevUmbraIndex] += insetNormal; |
| |
| SkPoint umbraPoint = nextPoint + insetNormal; |
| SkVector outsetNormal = nextNormal; |
| outsetNormal *= fRadius; |
| SkPoint penumbraPoint = nextPoint + outsetNormal; |
| |
| // For split edges, we're adding an average of two averages, so we multiply by another half |
| if (fSplitPreviousEdge) { |
| insetNormal *= 0.5f; |
| fPositions[fPrevUmbraIndex - 2] += insetNormal; |
| } |
| |
| // Split the edge to make sure we don't end up with a sharp alpha edge along the quad diagonal |
| if (fColors[fPrevUmbraIndex] != fUmbraColor && |
| nextPoint.distanceToSqd(fPositions[fPrevUmbraIndex]) > kMaxEdgeLenSqr) { |
| |
| // This is lacking 1/4 of the next inset -- we'll add it the next time we call addEdge() |
| SkPoint centerPoint = fPositions[fPrevUmbraIndex] + umbraPoint; |
| centerPoint *= 0.5f; |
| *fPositions.push() = centerPoint; |
| *fColors.push() = SkPMLerp(fUmbraColor, fColors[fPrevUmbraIndex], 128); |
| centerPoint = fPositions[fPositions.count()-2] + penumbraPoint; |
| centerPoint *= 0.5f; |
| *fPositions.push() = centerPoint; |
| *fColors.push() = fPenumbraColor; |
| |
| // set triangularization to get best interpolation of color |
| if (fColors[fPrevUmbraIndex] > fColors[fPositions.count() - 2]) { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 3; |
| *fIndices.push() = fPositions.count() - 2; |
| |
| *fIndices.push() = fPositions.count() - 3; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fPositions.count() - 2; |
| } else { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 2; |
| *fIndices.push() = fPositions.count() - 1; |
| |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fPositions.count() - 3; |
| } |
| |
| // if transparent, add point to first one in array and add to center fan |
| if (fTransparent) { |
| fPositions[0] += centerPoint; |
| ++fCentroidCount; |
| |
| *fIndices.push() = 0; |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 2; |
| } |
| |
| fSplitPreviousEdge = true; |
| if (fPrevUmbraIndex == fFirstVertexIndex) { |
| fSplitFirstEdge = true; |
| } |
| fPrevUmbraIndex = fPositions.count() - 2; |
| } else { |
| fSplitPreviousEdge = false; |
| } |
| |
| // add next quad |
| *fPositions.push() = umbraPoint; |
| *fColors.push() = fUmbraColor; |
| *fPositions.push() = penumbraPoint; |
| *fColors.push() = fPenumbraColor; |
| |
| // set triangularization to get best interpolation of color |
| if (fColors[fPrevUmbraIndex] > fColors[fPositions.count() - 2]) { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 3; |
| *fIndices.push() = fPositions.count() - 2; |
| |
| *fIndices.push() = fPositions.count() - 3; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fPositions.count() - 2; |
| } else { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 2; |
| *fIndices.push() = fPositions.count() - 1; |
| |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fPositions.count() - 3; |
| } |
| |
| // if transparent, add point to first one in array and add to center fan |
| if (fTransparent) { |
| fPositions[0] += nextPoint; |
| ++fCentroidCount; |
| |
| *fIndices.push() = 0; |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 2; |
| } |
| |
| fPrevUmbraIndex = fPositions.count() - 2; |
| fPrevPoint = nextPoint; |
| fPrevOutset = outsetNormal; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////////////////////////// |
| |
| class SkSpotShadowTessellator : public SkBaseShadowTessellator { |
| public: |
| SkSpotShadowTessellator(const SkPath& path, const SkMatrix& ctm, |
| const SkPoint3& zPlaneParams, const SkPoint3& lightPos, |
| SkScalar lightRadius, bool transparent); |
| |
| private: |
| void computeClipAndPathPolygons(const SkPath& path, const SkMatrix& ctm, |
| const SkMatrix& shadowTransform); |
| void computeClipVectorsAndTestCentroid(); |
| bool clipUmbraPoint(const SkPoint& umbraPoint, const SkPoint& centroid, SkPoint* clipPoint); |
| int getClosestUmbraPoint(const SkPoint& point); |
| |
| void handleLine(const SkPoint& p) override; |
| bool handlePolyPoint(const SkPoint& p); |
| |
| void mapPoints(SkScalar scale, const SkVector& xlate, SkPoint* pts, int count); |
| bool addInnerPoint(const SkPoint& pathPoint); |
| void addEdge(const SkVector& nextPoint, const SkVector& nextNormal); |
| |
| SkScalar offset(SkScalar z) { |
| float zRatio = SkTPin(z / (fLightZ - z), 0.0f, 0.95f); |
| return fLightRadius*zRatio; |
| } |
| |
| SkScalar fLightZ; |
| SkScalar fLightRadius; |
| SkScalar fOffsetAdjust; |
| |
| SkTDArray<SkPoint> fClipPolygon; |
| SkTDArray<SkVector> fClipVectors; |
| SkPoint fCentroid; |
| SkScalar fArea; |
| |
| SkTDArray<SkPoint> fPathPolygon; |
| SkTDArray<SkPoint> fUmbraPolygon; |
| int fCurrClipPoint; |
| int fCurrUmbraPoint; |
| bool fPrevUmbraOutside; |
| bool fFirstUmbraOutside; |
| bool fValidUmbra; |
| |
| typedef SkBaseShadowTessellator INHERITED; |
| }; |
| |
| SkSpotShadowTessellator::SkSpotShadowTessellator(const SkPath& path, const SkMatrix& ctm, |
| const SkPoint3& zPlaneParams, |
| const SkPoint3& lightPos, SkScalar lightRadius, |
| bool transparent) |
| : INHERITED(zPlaneParams, transparent) |
| , fLightZ(lightPos.fZ) |
| , fLightRadius(lightRadius) |
| , fOffsetAdjust(0) |
| , fCurrClipPoint(0) |
| , fPrevUmbraOutside(false) |
| , fFirstUmbraOutside(false) |
| , fValidUmbra(true) { |
| |
| // make sure we're not below the canvas plane |
| if (this->setZOffset(path.getBounds(), ctm.hasPerspective())) { |
| // Adjust light height and radius |
| fLightRadius *= (fLightZ + fZOffset) / fLightZ; |
| fLightZ += fZOffset; |
| } |
| |
| // Set radius and colors |
| SkPoint center = SkPoint::Make(path.getBounds().centerX(), path.getBounds().centerY()); |
| SkScalar occluderHeight = this->heightFunc(center.fX, center.fY) + fZOffset; |
| float zRatio = SkTPin(occluderHeight / (fLightZ - occluderHeight), 0.0f, 0.95f); |
| SkScalar radius = lightRadius * zRatio; |
| fRadius = radius; |
| fUmbraColor = SkColorSetARGB(255, 0, 0, 0); |
| fPenumbraColor = SkColorSetARGB(0, 0, 0, 0); |
| |
| // Compute the scale and translation for the spot shadow. |
| SkMatrix shadowTransform; |
| if (!ctm.hasPerspective()) { |
| SkScalar scale = fLightZ / (fLightZ - occluderHeight); |
| SkVector translate = SkVector::Make(-zRatio * lightPos.fX, -zRatio * lightPos.fY); |
| shadowTransform.setScaleTranslate(scale, scale, translate.fX, translate.fY); |
| } else { |
| // For perspective, we have a scale, a z-shear, and another projective divide -- |
| // this varies at each point so we can't use an affine transform. |
| // We'll just apply this to each generated point in turn. |
| shadowTransform.reset(); |
| // Also can't cull the center (for now). |
| fTransparent = true; |
| } |
| SkMatrix fullTransform = SkMatrix::Concat(shadowTransform, ctm); |
| |
| // Set up our reverse mapping |
| this->setTransformedHeightFunc(fullTransform); |
| |
| // TODO: calculate these reserves better |
| // Penumbra ring: 3*numPts |
| // Umbra ring: numPts |
| // Inner ring: numPts |
| fPositions.setReserve(5 * path.countPoints()); |
| fColors.setReserve(5 * path.countPoints()); |
| // Penumbra ring: 12*numPts |
| // Umbra ring: 3*numPts |
| fIndices.setReserve(15 * path.countPoints()); |
| fClipPolygon.setReserve(path.countPoints()); |
| |
| // compute rough clip bounds for umbra, plus offset polygon, plus centroid |
| this->computeClipAndPathPolygons(path, ctm, shadowTransform); |
| if (fClipPolygon.count() < 3 || fPathPolygon.count() < 3) { |
| return; |
| } |
| |
| // check to see if umbra collapses |
| SkScalar minDistSq = fCentroid.distanceToLineSegmentBetweenSqd(fPathPolygon[0], |
| fPathPolygon[1]); |
| SkRect bounds; |
| bounds.setBounds(&fPathPolygon[0], fPathPolygon.count()); |
| for (int i = 1; i < fPathPolygon.count(); ++i) { |
| int j = i + 1; |
| if (i == fPathPolygon.count() - 1) { |
| j = 0; |
| } |
| SkPoint currPoint = fPathPolygon[i]; |
| SkPoint nextPoint = fPathPolygon[j]; |
| SkScalar distSq = fCentroid.distanceToLineSegmentBetweenSqd(currPoint, nextPoint); |
| if (distSq < minDistSq) { |
| minDistSq = distSq; |
| } |
| } |
| static constexpr auto kTolerance = 1.0e-2f; |
| if (minDistSq < (radius + kTolerance)*(radius + kTolerance)) { |
| // if the umbra would collapse, we back off a bit on inner blur and adjust the alpha |
| SkScalar newRadius = SkScalarSqrt(minDistSq) - kTolerance; |
| fOffsetAdjust = newRadius - radius; |
| SkScalar ratio = 128 * (newRadius + radius) / radius; |
| // they aren't PMColors, but the interpolation algorithm is the same |
| fUmbraColor = SkPMLerp(fUmbraColor, fPenumbraColor, (unsigned)ratio); |
| radius = newRadius; |
| } |
| |
| // compute vectors for clip tests |
| this->computeClipVectorsAndTestCentroid(); |
| |
| // generate inner ring |
| if (!SkInsetConvexPolygon(&fPathPolygon[0], fPathPolygon.count(), radius, |
| &fUmbraPolygon)) { |
| // this shouldn't happen, but just in case we'll inset using the centroid |
| fValidUmbra = false; |
| } |
| |
| // walk around the path polygon, generate outer ring and connect to inner ring |
| if (fTransparent) { |
| *fPositions.push() = fCentroid; |
| *fColors.push() = fUmbraColor; |
| } |
| fCurrUmbraPoint = 0; |
| for (int i = 0; i < fPathPolygon.count(); ++i) { |
| if (!this->handlePolyPoint(fPathPolygon[i])) { |
| return; |
| } |
| } |
| |
| if (!this->indexCount()) { |
| return; |
| } |
| |
| // finish up the final verts |
| SkVector normal; |
| if (compute_normal(fPrevPoint, fFirstPoint, fDirection, &normal)) { |
| normal *= fRadius; |
| this->addArc(normal, true); |
| |
| // add to center fan |
| if (fTransparent) { |
| *fIndices.push() = 0; |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fFirstVertexIndex; |
| // or to clip ring |
| } else { |
| if (fFirstUmbraOutside) { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fFirstVertexIndex; |
| *fIndices.push() = fFirstVertexIndex + 1; |
| if (fPrevUmbraOutside) { |
| // fill out quad |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fFirstVertexIndex + 1; |
| *fIndices.push() = fPrevUmbraIndex + 1; |
| } |
| } else if (fPrevUmbraOutside) { |
| // add tri |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fFirstVertexIndex; |
| *fIndices.push() = fPrevUmbraIndex + 1; |
| } |
| } |
| |
| // add final edge |
| *fPositions.push() = fFirstPoint + normal; |
| *fColors.push() = fPenumbraColor; |
| |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = fPositions.count() - 2; |
| *fIndices.push() = fFirstVertexIndex; |
| |
| *fIndices.push() = fPositions.count() - 2; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fFirstVertexIndex; |
| |
| fPrevOutset = normal; |
| } |
| |
| // final fan |
| if (fPositions.count() >= 3) { |
| fPrevUmbraIndex = fFirstVertexIndex; |
| fPrevPoint = fFirstPoint; |
| if (this->addArc(fFirstOutset, false)) { |
| *fIndices.push() = fFirstVertexIndex; |
| *fIndices.push() = fPositions.count() - 1; |
| if (fFirstUmbraOutside) { |
| *fIndices.push() = fFirstVertexIndex + 2; |
| } else { |
| *fIndices.push() = fFirstVertexIndex + 1; |
| } |
| } else { |
| // no arc added, fix up by setting first penumbra point position to last one |
| if (fFirstUmbraOutside) { |
| fPositions[fFirstVertexIndex + 2] = fPositions[fPositions.count() - 1]; |
| } else { |
| fPositions[fFirstVertexIndex + 1] = fPositions[fPositions.count() - 1]; |
| } |
| } |
| } |
| |
| if (ctm.hasPerspective()) { |
| for (int i = 0; i < fPositions.count(); ++i) { |
| SkScalar pathZ = fTransformedHeightFunc(fPositions[i]); |
| SkScalar factor = SkScalarInvert(fLightZ - pathZ); |
| fPositions[i].fX = (fPositions[i].fX*fLightZ - lightPos.fX*pathZ)*factor; |
| fPositions[i].fY = (fPositions[i].fY*fLightZ - lightPos.fY*pathZ)*factor; |
| } |
| #ifdef DRAW_CENTROID |
| SkScalar pathZ = fTransformedHeightFunc(fCentroid); |
| SkScalar factor = SkScalarInvert(fLightZ - pathZ); |
| fCentroid.fX = (fCentroid.fX*fLightZ - lightPos.fX*pathZ)*factor; |
| fCentroid.fY = (fCentroid.fY*fLightZ - lightPos.fY*pathZ)*factor; |
| #endif |
| } |
| #ifdef DRAW_CENTROID |
| *fPositions.push() = fCentroid + SkVector::Make(-2, -2); |
| *fColors.push() = SkColorSetARGB(255, 0, 255, 255); |
| *fPositions.push() = fCentroid + SkVector::Make(2, -2); |
| *fColors.push() = SkColorSetARGB(255, 0, 255, 255); |
| *fPositions.push() = fCentroid + SkVector::Make(-2, 2); |
| *fColors.push() = SkColorSetARGB(255, 0, 255, 255); |
| *fPositions.push() = fCentroid + SkVector::Make(2, 2); |
| *fColors.push() = SkColorSetARGB(255, 0, 255, 255); |
| |
| *fIndices.push() = fPositions.count() - 4; |
| *fIndices.push() = fPositions.count() - 2; |
| *fIndices.push() = fPositions.count() - 1; |
| |
| *fIndices.push() = fPositions.count() - 4; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = fPositions.count() - 3; |
| #endif |
| |
| fSucceeded = true; |
| } |
| |
| void SkSpotShadowTessellator::computeClipAndPathPolygons(const SkPath& path, const SkMatrix& ctm, |
| const SkMatrix& shadowTransform) { |
| |
| fPathPolygon.setReserve(path.countPoints()); |
| |
| // Walk around the path and compute clip polygon and path polygon. |
| // Will also accumulate sum of areas for centroid. |
| // For Bezier curves, we compute additional interior points on curve. |
| SkPath::Iter iter(path, true); |
| SkPoint pts[4]; |
| SkPath::Verb verb; |
| |
| fClipPolygon.reset(); |
| |
| // init centroid |
| fCentroid = SkPoint::Make(0, 0); |
| fArea = 0; |
| |
| // coefficients to compute cubic Bezier at t = 5/16 |
| static constexpr SkScalar kA = 0.32495117187f; |
| static constexpr SkScalar kB = 0.44311523437f; |
| static constexpr SkScalar kC = 0.20141601562f; |
| static constexpr SkScalar kD = 0.03051757812f; |
| |
| SkPoint curvePoint; |
| SkScalar w; |
| while ((verb = iter.next(pts)) != SkPath::kDone_Verb) { |
| switch (verb) { |
| case SkPath::kLine_Verb: |
| ctm.mapPoints(&pts[1], 1); |
| *fClipPolygon.push() = pts[1]; |
| this->INHERITED::handleLine(shadowTransform, &pts[1]); |
| break; |
| case SkPath::kQuad_Verb: |
| ctm.mapPoints(pts, 3); |
| // point at t = 1/2 |
| curvePoint.fX = 0.25f*pts[0].fX + 0.5f*pts[1].fX + 0.25f*pts[2].fX; |
| curvePoint.fY = 0.25f*pts[0].fY + 0.5f*pts[1].fY + 0.25f*pts[2].fY; |
| *fClipPolygon.push() = curvePoint; |
| *fClipPolygon.push() = pts[2]; |
| this->handleQuad(shadowTransform, pts); |
| break; |
| case SkPath::kConic_Verb: |
| ctm.mapPoints(pts, 3); |
| w = iter.conicWeight(); |
| // point at t = 1/2 |
| curvePoint.fX = 0.25f*pts[0].fX + w*0.5f*pts[1].fX + 0.25f*pts[2].fX; |
| curvePoint.fY = 0.25f*pts[0].fY + w*0.5f*pts[1].fY + 0.25f*pts[2].fY; |
| curvePoint *= SkScalarInvert(0.5f + 0.5f*w); |
| *fClipPolygon.push() = curvePoint; |
| *fClipPolygon.push() = pts[2]; |
| this->handleConic(shadowTransform, pts, w); |
| break; |
| case SkPath::kCubic_Verb: |
| ctm.mapPoints(pts, 4); |
| // point at t = 5/16 |
| curvePoint.fX = kA*pts[0].fX + kB*pts[1].fX + kC*pts[2].fX + kD*pts[3].fX; |
| curvePoint.fY = kA*pts[0].fY + kB*pts[1].fY + kC*pts[2].fY + kD*pts[3].fY; |
| *fClipPolygon.push() = curvePoint; |
| // point at t = 11/16 |
| curvePoint.fX = kD*pts[0].fX + kC*pts[1].fX + kB*pts[2].fX + kA*pts[3].fX; |
| curvePoint.fY = kD*pts[0].fY + kC*pts[1].fY + kB*pts[2].fY + kA*pts[3].fY; |
| *fClipPolygon.push() = curvePoint; |
| *fClipPolygon.push() = pts[3]; |
| this->handleCubic(shadowTransform, pts); |
| break; |
| case SkPath::kMove_Verb: |
| case SkPath::kClose_Verb: |
| case SkPath::kDone_Verb: |
| break; |
| default: |
| SkDEBUGFAIL("unknown verb"); |
| } |
| } |
| |
| // finish centroid |
| if (fPathPolygon.count() > 0) { |
| SkPoint currPoint = fPathPolygon[fPathPolygon.count() - 1]; |
| SkPoint nextPoint = fPathPolygon[0]; |
| SkScalar quadArea = currPoint.cross(nextPoint); |
| fCentroid.fX += (currPoint.fX + nextPoint.fX) * quadArea; |
| fCentroid.fY += (currPoint.fY + nextPoint.fY) * quadArea; |
| fArea += quadArea; |
| fCentroid *= SK_Scalar1 / (3 * fArea); |
| } |
| |
| fCurrClipPoint = fClipPolygon.count() - 1; |
| } |
| |
| void SkSpotShadowTessellator::computeClipVectorsAndTestCentroid() { |
| SkASSERT(fClipPolygon.count() >= 3); |
| |
| // init clip vectors |
| SkVector v0 = fClipPolygon[1] - fClipPolygon[0]; |
| *fClipVectors.push() = v0; |
| |
| // init centroid check |
| bool hiddenCentroid = true; |
| SkVector v1 = fCentroid - fClipPolygon[0]; |
| SkScalar initCross = v0.cross(v1); |
| |
| for (int p = 1; p < fClipPolygon.count(); ++p) { |
| // add to clip vectors |
| v0 = fClipPolygon[(p + 1) % fClipPolygon.count()] - fClipPolygon[p]; |
| *fClipVectors.push() = v0; |
| // Determine if transformed centroid is inside clipPolygon. |
| v1 = fCentroid - fClipPolygon[p]; |
| if (initCross*v0.cross(v1) <= 0) { |
| hiddenCentroid = false; |
| } |
| } |
| SkASSERT(fClipVectors.count() == fClipPolygon.count()); |
| |
| fTransparent = fTransparent || !hiddenCentroid; |
| } |
| |
| bool SkSpotShadowTessellator::clipUmbraPoint(const SkPoint& umbraPoint, const SkPoint& centroid, |
| SkPoint* clipPoint) { |
| SkVector segmentVector = centroid - umbraPoint; |
| |
| int startClipPoint = fCurrClipPoint; |
| do { |
| SkVector dp = umbraPoint - fClipPolygon[fCurrClipPoint]; |
| SkScalar denom = fClipVectors[fCurrClipPoint].cross(segmentVector); |
| SkScalar t_num = dp.cross(segmentVector); |
| // if line segments are nearly parallel |
| if (SkScalarNearlyZero(denom)) { |
| // and collinear |
| if (SkScalarNearlyZero(t_num)) { |
| return false; |
| } |
| // otherwise are separate, will try the next poly segment |
| // else if crossing lies within poly segment |
| } else if (t_num >= 0 && t_num <= denom) { |
| SkScalar s_num = dp.cross(fClipVectors[fCurrClipPoint]); |
| // if umbra point is inside the clip polygon |
| if (s_num >= 0 && s_num <= denom) { |
| segmentVector *= s_num/denom; |
| *clipPoint = umbraPoint + segmentVector; |
| return true; |
| } |
| } |
| fCurrClipPoint = (fCurrClipPoint + 1) % fClipPolygon.count(); |
| } while (fCurrClipPoint != startClipPoint); |
| |
| return false; |
| } |
| |
| int SkSpotShadowTessellator::getClosestUmbraPoint(const SkPoint& p) { |
| SkScalar minDistance = p.distanceToSqd(fUmbraPolygon[fCurrUmbraPoint]); |
| int index = fCurrUmbraPoint; |
| int dir = 1; |
| int next = (index + dir) % fUmbraPolygon.count(); |
| |
| // init travel direction |
| SkScalar distance = p.distanceToSqd(fUmbraPolygon[next]); |
| if (distance < minDistance) { |
| index = next; |
| minDistance = distance; |
| } else { |
| dir = fUmbraPolygon.count()-1; |
| } |
| |
| // iterate until we find a point that increases the distance |
| next = (index + dir) % fUmbraPolygon.count(); |
| distance = p.distanceToSqd(fUmbraPolygon[next]); |
| while (distance < minDistance) { |
| index = next; |
| minDistance = distance; |
| next = (index + dir) % fUmbraPolygon.count(); |
| distance = p.distanceToSqd(fUmbraPolygon[next]); |
| } |
| |
| fCurrUmbraPoint = index; |
| return index; |
| } |
| |
| void SkSpotShadowTessellator::mapPoints(SkScalar scale, const SkVector& xlate, |
| SkPoint* pts, int count) { |
| // TODO: vectorize |
| for (int i = 0; i < count; ++i) { |
| pts[i] *= scale; |
| pts[i] += xlate; |
| } |
| } |
| |
| static bool duplicate_pt(const SkPoint& p0, const SkPoint& p1) { |
| static constexpr SkScalar kClose = (SK_Scalar1 / 16); |
| static constexpr SkScalar kCloseSqd = kClose*kClose; |
| |
| SkScalar distSq = p0.distanceToSqd(p1); |
| return distSq < kCloseSqd; |
| } |
| |
| static SkScalar perp_dot(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2) { |
| SkVector v0 = p1 - p0; |
| SkVector v1 = p2 - p0; |
| return v0.cross(v1); |
| } |
| |
| static bool is_collinear(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2) { |
| return (SkScalarNearlyZero(perp_dot(p0, p1, p2))); |
| } |
| |
| void SkSpotShadowTessellator::handleLine(const SkPoint& p) { |
| // remove coincident points and add to centroid |
| if (fPathPolygon.count() > 0) { |
| const SkPoint& lastPoint = fPathPolygon[fPathPolygon.count() - 1]; |
| if (duplicate_pt(p, lastPoint)) { |
| return; |
| } |
| SkScalar quadArea = lastPoint.cross(p); |
| fCentroid.fX += (p.fX + lastPoint.fX) * quadArea; |
| fCentroid.fY += (p.fY + lastPoint.fY) * quadArea; |
| fArea += quadArea; |
| } |
| |
| // try to remove collinear points |
| if (fPathPolygon.count() > 1 && is_collinear(fPathPolygon[fPathPolygon.count()-2], |
| fPathPolygon[fPathPolygon.count()-1], |
| p)) { |
| fPathPolygon[fPathPolygon.count() - 1] = p; |
| } else { |
| *fPathPolygon.push() = p; |
| } |
| } |
| |
| bool SkSpotShadowTessellator::handlePolyPoint(const SkPoint& p) { |
| if (fInitPoints.count() < 2) { |
| *fInitPoints.push() = p; |
| return true; |
| } |
| |
| if (fInitPoints.count() == 2) { |
| // determine if cw or ccw |
| SkScalar perpDot = perp_dot(fInitPoints[0], fInitPoints[1], p); |
| if (SkScalarNearlyZero(perpDot)) { |
| // nearly parallel, just treat as straight line and continue |
| fInitPoints[1] = p; |
| return true; |
| } |
| |
| // if perpDot > 0, winding is ccw |
| fDirection = (perpDot > 0) ? -1 : 1; |
| |
| // add first quad |
| if (!compute_normal(fInitPoints[0], fInitPoints[1], fDirection, &fFirstOutset)) { |
| // first two points are incident, make the third point the second and continue |
| fInitPoints[1] = p; |
| return true; |
| } |
| |
| fFirstOutset *= fRadius; |
| fFirstPoint = fInitPoints[0]; |
| fFirstVertexIndex = fPositions.count(); |
| fPrevOutset = fFirstOutset; |
| fPrevPoint = fFirstPoint; |
| fPrevUmbraIndex = -1; |
| |
| this->addInnerPoint(fFirstPoint); |
| fPrevUmbraIndex = fFirstVertexIndex; |
| |
| if (!fTransparent) { |
| SkPoint clipPoint; |
| bool isOutside = this->clipUmbraPoint(fPositions[fFirstVertexIndex], |
| fCentroid, &clipPoint); |
| if (isOutside) { |
| *fPositions.push() = clipPoint; |
| *fColors.push() = fUmbraColor; |
| } |
| fPrevUmbraOutside = isOutside; |
| fFirstUmbraOutside = isOutside; |
| } |
| |
| SkPoint newPoint = fFirstPoint + fFirstOutset; |
| *fPositions.push() = newPoint; |
| *fColors.push() = fPenumbraColor; |
| this->addEdge(fInitPoints[1], fFirstOutset); |
| |
| // to ensure we skip this block next time |
| *fInitPoints.push() = p; |
| } |
| |
| // if concave, abort |
| SkScalar perpDot = perp_dot(fInitPoints[1], fInitPoints[2], p); |
| if (fDirection*perpDot > 0) { |
| return false; |
| } |
| |
| SkVector normal; |
| if (compute_normal(fPrevPoint, p, fDirection, &normal)) { |
| normal *= fRadius; |
| this->addArc(normal, true); |
| this->addEdge(p, normal); |
| fInitPoints[1] = fInitPoints[2]; |
| fInitPoints[2] = p; |
| } |
| |
| return true; |
| } |
| |
| bool SkSpotShadowTessellator::addInnerPoint(const SkPoint& pathPoint) { |
| SkPoint umbraPoint; |
| if (!fValidUmbra) { |
| SkVector v = fCentroid - pathPoint; |
| v *= 0.95f; |
| umbraPoint = pathPoint + v; |
| } else { |
| umbraPoint = fUmbraPolygon[this->getClosestUmbraPoint(pathPoint)]; |
| } |
| |
| fPrevPoint = pathPoint; |
| |
| // merge "close" points |
| if (fPrevUmbraIndex == -1 || |
| !duplicate_pt(umbraPoint, fPositions[fPrevUmbraIndex])) { |
| *fPositions.push() = umbraPoint; |
| *fColors.push() = fUmbraColor; |
| |
| return false; |
| } else { |
| return true; |
| } |
| } |
| |
| void SkSpotShadowTessellator::addEdge(const SkPoint& nextPoint, const SkVector& nextNormal) { |
| // add next umbra point |
| bool duplicate = this->addInnerPoint(nextPoint); |
| int prevPenumbraIndex = duplicate ? fPositions.count()-1 : fPositions.count()-2; |
| int currUmbraIndex = duplicate ? fPrevUmbraIndex : fPositions.count()-1; |
| |
| if (!duplicate) { |
| // add to center fan if transparent or centroid showing |
| if (fTransparent) { |
| *fIndices.push() = 0; |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = currUmbraIndex; |
| // otherwise add to clip ring |
| } else { |
| SkPoint clipPoint; |
| bool isOutside = this->clipUmbraPoint(fPositions[currUmbraIndex], fCentroid, |
| &clipPoint); |
| if (isOutside) { |
| *fPositions.push() = clipPoint; |
| *fColors.push() = fUmbraColor; |
| |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = currUmbraIndex; |
| *fIndices.push() = currUmbraIndex + 1; |
| if (fPrevUmbraOutside) { |
| // fill out quad |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = currUmbraIndex + 1; |
| *fIndices.push() = fPrevUmbraIndex + 1; |
| } |
| } else if (fPrevUmbraOutside) { |
| // add tri |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = currUmbraIndex; |
| *fIndices.push() = fPrevUmbraIndex + 1; |
| } |
| fPrevUmbraOutside = isOutside; |
| } |
| } |
| |
| // add next penumbra point and quad |
| SkPoint newPoint = nextPoint + nextNormal; |
| *fPositions.push() = newPoint; |
| *fColors.push() = fPenumbraColor; |
| |
| if (!duplicate) { |
| *fIndices.push() = fPrevUmbraIndex; |
| *fIndices.push() = prevPenumbraIndex; |
| *fIndices.push() = currUmbraIndex; |
| } |
| |
| *fIndices.push() = prevPenumbraIndex; |
| *fIndices.push() = fPositions.count() - 1; |
| *fIndices.push() = currUmbraIndex; |
| |
| fPrevUmbraIndex = currUmbraIndex; |
| fPrevOutset = nextNormal; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////////////////////////// |
| |
| sk_sp<SkVertices> SkShadowTessellator::MakeAmbient(const SkPath& path, const SkMatrix& ctm, |
| const SkPoint3& zPlane, bool transparent) { |
| SkAmbientShadowTessellator ambientTess(path, ctm, zPlane, transparent); |
| return ambientTess.releaseVertices(); |
| } |
| |
| sk_sp<SkVertices> SkShadowTessellator::MakeSpot(const SkPath& path, const SkMatrix& ctm, |
| const SkPoint3& zPlane, const SkPoint3& lightPos, |
| SkScalar lightRadius, bool transparent) { |
| SkSpotShadowTessellator spotTess(path, ctm, zPlane, lightPos, lightRadius, transparent); |
| return spotTess.releaseVertices(); |
| } |
