diff options
| -rw-r--r-- | src/gpu/GrTessellator.cpp | 95 |
1 files changed, 53 insertions, 42 deletions
diff --git a/src/gpu/GrTessellator.cpp b/src/gpu/GrTessellator.cpp index 9ce1a739df..4024ad0c16 100644 --- a/src/gpu/GrTessellator.cpp +++ b/src/gpu/GrTessellator.cpp @@ -260,6 +260,36 @@ inline void round(SkPoint* p) { p->fY = SkScalarRoundToScalar(p->fY * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); } +// A line equation in implicit form. fA * x + fB * y + fC = 0, for all points (x, y) on the line. +struct Line { + Line(Vertex* p, Vertex* q) : Line(p->fPoint, q->fPoint) {} + Line(const SkPoint& p, const SkPoint& q) + : fA(static_cast<double>(q.fY) - p.fY) // a = dY + , fB(static_cast<double>(p.fX) - q.fX) // b = -dX + , fC(static_cast<double>(p.fY) * q.fX - // c = cross(q, p) + static_cast<double>(p.fX) * q.fY) {} + double dist(const SkPoint& p) const { + return fA * p.fX + fB * p.fY + fC; + } + double magSq() const { + return fA * fA + fB * fB; + } + + // Compute the intersection of two (infinite) Lines. + bool intersect(const Line& other, SkPoint* point) { + double denom = fA * other.fB - fB * other.fA; + if (denom == 0.0) { + return false; + } + double scale = 1.0f / denom; + point->fX = SkDoubleToScalar((fB * other.fC - other.fB * fC) * scale); + point->fY = SkDoubleToScalar((other.fA * fC - fA * other.fC) * scale); + round(point); + return true; + } + double fA, fB, fC; +}; + /** * An Edge joins a top Vertex to a bottom Vertex. Edge ordering for the list of "edges above" and * "edge below" a vertex as well as for the active edge list is handled by isLeftOf()/isRightOf(). @@ -296,8 +326,8 @@ struct Edge { , fRightPolyPrev(nullptr) , fRightPolyNext(nullptr) , fUsedInLeftPoly(false) - , fUsedInRightPoly(false) { - recompute(); + , fUsedInRightPoly(false) + , fLine(top, bottom) { } int fWinding; // 1 == edge goes downward; -1 = edge goes upward. Vertex* fTop; // The top vertex in vertex-sort-order (sweep_lt). @@ -316,23 +346,18 @@ struct Edge { Edge* fRightPolyNext; bool fUsedInLeftPoly; bool fUsedInRightPoly; - double fDX; // The line equation for this edge, in implicit form. - double fDY; // fDY * x + fDX * y + fC = 0, for point (x, y) on the line. - double fC; + Line fLine; double dist(const SkPoint& p) const { - return fDY * p.fX - fDX * p.fY + fC; + return fLine.dist(p); } bool isRightOf(Vertex* v) const { - return dist(v->fPoint) < 0.0; + return fLine.dist(v->fPoint) < 0.0; } bool isLeftOf(Vertex* v) const { - return dist(v->fPoint) > 0.0; + return fLine.dist(v->fPoint) > 0.0; } void recompute() { - fDX = static_cast<double>(fBottom->fPoint.fX) - fTop->fPoint.fX; - fDY = static_cast<double>(fBottom->fPoint.fY) - fTop->fPoint.fY; - fC = static_cast<double>(fTop->fPoint.fY) * fBottom->fPoint.fX - - static_cast<double>(fTop->fPoint.fX) * fBottom->fPoint.fY; + fLine = Line(fTop, fBottom); } bool intersect(const Edge& other, SkPoint* p) { LOG("intersecting %g -> %g with %g -> %g\n", @@ -341,14 +366,14 @@ struct Edge { if (fTop == other.fTop || fBottom == other.fBottom) { return false; } - double denom = fDX * other.fDY - fDY * other.fDX; + double denom = fLine.fA * other.fLine.fB - fLine.fB * other.fLine.fA; if (denom == 0.0) { return false; } double dx = static_cast<double>(fTop->fPoint.fX) - other.fTop->fPoint.fX; double dy = static_cast<double>(fTop->fPoint.fY) - other.fTop->fPoint.fY; - double sNumer = dy * other.fDX - dx * other.fDY; - double tNumer = dy * fDX - dx * fDY; + double sNumer = -dy * other.fLine.fB - dx * other.fLine.fA; + double tNumer = -dy * fLine.fB - dx * fLine.fA; // If (sNumer / denom) or (tNumer / denom) is not in [0..1], exit early. // This saves us doing the divide below unless absolutely necessary. if (denom > 0.0 ? (sNumer < 0.0 || sNumer > denom || tNumer < 0.0 || tNumer > denom) @@ -357,8 +382,8 @@ struct Edge { } double s = sNumer / denom; SkASSERT(s >= 0.0 && s <= 1.0); - p->fX = SkDoubleToScalar(fTop->fPoint.fX + s * fDX); - p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fDY); + p->fX = SkDoubleToScalar(fTop->fPoint.fX - s * fLine.fB); + p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fLine.fA); return true; } }; @@ -1423,22 +1448,9 @@ Vertex* remove_non_boundary_edges(Vertex* vertices, SkPath::FillType fillType, return vertices; } -// This is different from Edge::intersect, in that it intersects lines, not line segments. -bool intersect(const Edge& a, const Edge& b, SkPoint* point) { - double denom = a.fDX * b.fDY - a.fDY * b.fDX; - if (denom == 0.0) { - return false; - } - double scale = 1.0f / denom; - point->fX = SkDoubleToScalar((b.fDX * a.fC - a.fDX * b.fC) * scale); - point->fY = SkDoubleToScalar((b.fDY * a.fC - a.fDY * b.fC) * scale); - round(point); - return true; -} - void get_edge_normal(const Edge* e, SkVector* normal) { - normal->setNormalize(SkDoubleToScalar(e->fDX) * e->fWinding, - SkDoubleToScalar(e->fDY) * e->fWinding); + normal->setNormalize(SkDoubleToScalar(-e->fLine.fB) * e->fWinding, + SkDoubleToScalar(e->fLine.fA) * e->fWinding); } // Stage 5c: detect and remove "pointy" vertices whose edge normals point in opposite directions @@ -1455,7 +1467,7 @@ void simplify_boundary(EdgeList* boundary, Comparator& c, SkChunkAlloc& alloc) { double dist = e->dist(prev->fPoint); SkVector normal; get_edge_normal(e, &normal); - float denom = 0.25f * static_cast<float>(e->fDX * e->fDX + e->fDY * e->fDY); + float denom = 0.25f * static_cast<float>(e->fLine.magSq()); if (prevNormal.dot(normal) < 0.0 && (dist * dist) <= denom) { Edge* join = new_edge(prev, next, alloc, c); insert_edge(join, e, boundary); @@ -1485,24 +1497,23 @@ void boundary_to_aa_mesh(EdgeList* boundary, VertexList* mesh, Comparator& c, Sk EdgeList outerContour; Edge* prevEdge = boundary->fTail; float radius = 0.5f; - double offset = radius * sqrt(prevEdge->fDX * prevEdge->fDX + prevEdge->fDY * prevEdge->fDY) - * prevEdge->fWinding; - Edge prevInner(prevEdge->fTop, prevEdge->fBottom, prevEdge->fWinding); + double offset = radius * sqrt(prevEdge->fLine.magSq()) * prevEdge->fWinding; + Line prevInner(prevEdge->fTop, prevEdge->fBottom); prevInner.fC -= offset; - Edge prevOuter(prevEdge->fTop, prevEdge->fBottom, prevEdge->fWinding); + Line prevOuter(prevEdge->fTop, prevEdge->fBottom); prevOuter.fC += offset; VertexList innerVertices; VertexList outerVertices; SkScalar innerCount = SK_Scalar1, outerCount = SK_Scalar1; for (Edge* e = boundary->fHead; e != nullptr; e = e->fRight) { - double offset = radius * sqrt(e->fDX * e->fDX + e->fDY * e->fDY) * e->fWinding; - Edge inner(e->fTop, e->fBottom, e->fWinding); + double offset = radius * sqrt(e->fLine.magSq()) * e->fWinding; + Line inner(e->fTop, e->fBottom); inner.fC -= offset; - Edge outer(e->fTop, e->fBottom, e->fWinding); + Line outer(e->fTop, e->fBottom); outer.fC += offset; SkPoint innerPoint, outerPoint; - if (intersect(prevInner, inner, &innerPoint) && - intersect(prevOuter, outer, &outerPoint)) { + if (prevInner.intersect(inner, &innerPoint) && + prevOuter.intersect(outer, &outerPoint)) { Vertex* innerVertex = ALLOC_NEW(Vertex, (innerPoint, 255), alloc); Vertex* outerVertex = ALLOC_NEW(Vertex, (outerPoint, 0), alloc); if (innerVertices.fTail && outerVertices.fTail) { |