| /* |
| * 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 "GrTessellator.h" |
| |
| #include "GrDefaultGeoProcFactory.h" |
| #include "GrPathUtils.h" |
| |
| #include "SkArenaAlloc.h" |
| #include "SkGeometry.h" |
| #include "SkPath.h" |
| |
| #include <stdio.h> |
| |
| /* |
| * There are six stages to the basic algorithm: |
| * |
| * 1) Linearize the path contours into piecewise linear segments (path_to_contours()). |
| * 2) Build a mesh of edges connecting the vertices (build_edges()). |
| * 3) Sort the vertices in Y (and secondarily in X) (merge_sort()). |
| * 4) Simplify the mesh by inserting new vertices at intersecting edges (simplify()). |
| * 5) Tessellate the simplified mesh into monotone polygons (tessellate()). |
| * 6) Triangulate the monotone polygons directly into a vertex buffer (polys_to_triangles()). |
| * |
| * For screenspace antialiasing, the algorithm is modified as follows: |
| * |
| * Run steps 1-5 above to produce polygons. |
| * 5b) Apply fill rules to extract boundary contours from the polygons (extract_boundaries()). |
| * 5c) Simplify boundaries to remove "pointy" vertices that cause inversions (simplify_boundary()). |
| * 5d) Displace edges by half a pixel inward and outward along their normals. Intersect to find |
| * new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a new |
| * antialiased mesh from those vertices (stroke_boundary()). |
| * Run steps 3-6 above on the new mesh, and produce antialiased triangles. |
| * |
| * The vertex sorting in step (3) is a merge sort, since it plays well with the linked list |
| * of vertices (and the necessity of inserting new vertices on intersection). |
| * |
| * Stages (4) and (5) use an active edge list -- a list of all edges for which the |
| * sweep line has crossed the top vertex, but not the bottom vertex. It's sorted |
| * left-to-right based on the point where both edges are active (when both top vertices |
| * have been seen, so the "lower" top vertex of the two). If the top vertices are equal |
| * (shared), it's sorted based on the last point where both edges are active, so the |
| * "upper" bottom vertex. |
| * |
| * The most complex step is the simplification (4). It's based on the Bentley-Ottman |
| * line-sweep algorithm, but due to floating point inaccuracy, the intersection points are |
| * not exact and may violate the mesh topology or active edge list ordering. We |
| * accommodate this by adjusting the topology of the mesh and AEL to match the intersection |
| * points. This occurs in two ways: |
| * |
| * A) Intersections may cause a shortened edge to no longer be ordered with respect to its |
| * neighbouring edges at the top or bottom vertex. This is handled by merging the |
| * edges (merge_collinear_edges()). |
| * B) Intersections may cause an edge to violate the left-to-right ordering of the |
| * active edge list. This is handled by detecting potential violations and rewinding |
| * the active edge list to the vertex before they occur (rewind() during merging, |
| * rewind_if_necessary() during splitting). |
| * |
| * The tessellation steps (5) and (6) are based on "Triangulating Simple Polygons and |
| * Equivalent Problems" (Fournier and Montuno); also a line-sweep algorithm. Note that it |
| * currently uses a linked list for the active edge list, rather than a 2-3 tree as the |
| * paper describes. The 2-3 tree gives O(lg N) lookups, but insertion and removal also |
| * become O(lg N). In all the test cases, it was found that the cost of frequent O(lg N) |
| * insertions and removals was greater than the cost of infrequent O(N) lookups with the |
| * linked list implementation. With the latter, all removals are O(1), and most insertions |
| * are O(1), since we know the adjacent edge in the active edge list based on the topology. |
| * Only type 2 vertices (see paper) require the O(N) lookups, and these are much less |
| * frequent. There may be other data structures worth investigating, however. |
| * |
| * Note that the orientation of the line sweep algorithms is determined by the aspect ratio of the |
| * path bounds. When the path is taller than it is wide, we sort vertices based on increasing Y |
| * coordinate, and secondarily by increasing X coordinate. When the path is wider than it is tall, |
| * we sort by increasing X coordinate, but secondarily by *decreasing* Y coordinate. This is so |
| * that the "left" and "right" orientation in the code remains correct (edges to the left are |
| * increasing in Y; edges to the right are decreasing in Y). That is, the setting rotates 90 |
| * degrees counterclockwise, rather that transposing. |
| */ |
| |
| #define LOGGING_ENABLED 0 |
| |
| #if LOGGING_ENABLED |
| #define LOG printf |
| #else |
| #define LOG(...) |
| #endif |
| |
| namespace { |
| |
| const int kArenaChunkSize = 16 * 1024; |
| |
| struct Vertex; |
| struct Edge; |
| struct Poly; |
| |
| template <class T, T* T::*Prev, T* T::*Next> |
| void list_insert(T* t, T* prev, T* next, T** head, T** tail) { |
| t->*Prev = prev; |
| t->*Next = next; |
| if (prev) { |
| prev->*Next = t; |
| } else if (head) { |
| *head = t; |
| } |
| if (next) { |
| next->*Prev = t; |
| } else if (tail) { |
| *tail = t; |
| } |
| } |
| |
| template <class T, T* T::*Prev, T* T::*Next> |
| void list_remove(T* t, T** head, T** tail) { |
| if (t->*Prev) { |
| t->*Prev->*Next = t->*Next; |
| } else if (head) { |
| *head = t->*Next; |
| } |
| if (t->*Next) { |
| t->*Next->*Prev = t->*Prev; |
| } else if (tail) { |
| *tail = t->*Prev; |
| } |
| t->*Prev = t->*Next = nullptr; |
| } |
| |
| /** |
| * Vertices are used in three ways: first, the path contours are converted into a |
| * circularly-linked list of Vertices for each contour. After edge construction, the same Vertices |
| * are re-ordered by the merge sort according to the sweep_lt comparator (usually, increasing |
| * in Y) using the same fPrev/fNext pointers that were used for the contours, to avoid |
| * reallocation. Finally, MonotonePolys are built containing a circularly-linked list of |
| * Vertices. (Currently, those Vertices are newly-allocated for the MonotonePolys, since |
| * an individual Vertex from the path mesh may belong to multiple |
| * MonotonePolys, so the original Vertices cannot be re-used. |
| */ |
| |
| struct Vertex { |
| Vertex(const SkPoint& point, uint8_t alpha) |
| : fPoint(point), fPrev(nullptr), fNext(nullptr) |
| , fFirstEdgeAbove(nullptr), fLastEdgeAbove(nullptr) |
| , fFirstEdgeBelow(nullptr), fLastEdgeBelow(nullptr) |
| , fLeftEnclosingEdge(nullptr), fRightEnclosingEdge(nullptr) |
| , fPartner(nullptr) |
| , fAlpha(alpha) |
| #if LOGGING_ENABLED |
| , fID (-1.0f) |
| #endif |
| {} |
| SkPoint fPoint; // Vertex position |
| Vertex* fPrev; // Linked list of contours, then Y-sorted vertices. |
| Vertex* fNext; // " |
| Edge* fFirstEdgeAbove; // Linked list of edges above this vertex. |
| Edge* fLastEdgeAbove; // " |
| Edge* fFirstEdgeBelow; // Linked list of edges below this vertex. |
| Edge* fLastEdgeBelow; // " |
| Edge* fLeftEnclosingEdge; // Nearest edge in the AEL left of this vertex. |
| Edge* fRightEnclosingEdge; // Nearest edge in the AEL right of this vertex. |
| Vertex* fPartner; // Corresponding inner or outer vertex (for AA). |
| uint8_t fAlpha; |
| #if LOGGING_ENABLED |
| float fID; // Identifier used for logging. |
| #endif |
| }; |
| |
| /***************************************************************************************/ |
| |
| struct AAParams { |
| bool fTweakAlpha; |
| GrColor fColor; |
| }; |
| |
| typedef bool (*CompareFunc)(const SkPoint& a, const SkPoint& b); |
| |
| bool sweep_lt_horiz(const SkPoint& a, const SkPoint& b) { |
| return a.fX < b.fX || (a.fX == b.fX && a.fY > b.fY); |
| } |
| |
| bool sweep_lt_vert(const SkPoint& a, const SkPoint& b) { |
| return a.fY < b.fY || (a.fY == b.fY && a.fX < b.fX); |
| } |
| |
| struct Comparator { |
| enum class Direction { kVertical, kHorizontal }; |
| Comparator(Direction direction) : fDirection(direction) {} |
| bool sweep_lt(const SkPoint& a, const SkPoint& b) const { |
| return fDirection == Direction::kHorizontal ? sweep_lt_horiz(a, b) : sweep_lt_vert(a, b); |
| } |
| Direction fDirection; |
| }; |
| |
| inline void* emit_vertex(Vertex* v, const AAParams* aaParams, void* data) { |
| if (!aaParams) { |
| SkPoint* d = static_cast<SkPoint*>(data); |
| *d++ = v->fPoint; |
| return d; |
| } |
| if (aaParams->fTweakAlpha) { |
| auto d = static_cast<GrDefaultGeoProcFactory::PositionColorAttr*>(data); |
| d->fPosition = v->fPoint; |
| d->fColor = SkAlphaMulQ(aaParams->fColor, SkAlpha255To256(v->fAlpha)); |
| d++; |
| return d; |
| } |
| auto d = static_cast<GrDefaultGeoProcFactory::PositionColorCoverageAttr*>(data); |
| d->fPosition = v->fPoint; |
| d->fColor = aaParams->fColor; |
| d->fCoverage = GrNormalizeByteToFloat(v->fAlpha); |
| d++; |
| return d; |
| } |
| |
| void* emit_triangle(Vertex* v0, Vertex* v1, Vertex* v2, const AAParams* aaParams, void* data) { |
| LOG("emit_triangle (%g, %g) %d\n", v0->fPoint.fX, v0->fPoint.fY, v0->fAlpha); |
| LOG(" (%g, %g) %d\n", v1->fPoint.fX, v1->fPoint.fY, v1->fAlpha); |
| LOG(" (%g, %g) %d\n", v2->fPoint.fX, v2->fPoint.fY, v2->fAlpha); |
| #if TESSELLATOR_WIREFRAME |
| data = emit_vertex(v0, aaParams, data); |
| data = emit_vertex(v1, aaParams, data); |
| data = emit_vertex(v1, aaParams, data); |
| data = emit_vertex(v2, aaParams, data); |
| data = emit_vertex(v2, aaParams, data); |
| data = emit_vertex(v0, aaParams, data); |
| #else |
| data = emit_vertex(v0, aaParams, data); |
| data = emit_vertex(v1, aaParams, data); |
| data = emit_vertex(v2, aaParams, data); |
| #endif |
| return data; |
| } |
| |
| struct VertexList { |
| VertexList() : fHead(nullptr), fTail(nullptr) {} |
| VertexList(Vertex* head, Vertex* tail) : fHead(head), fTail(tail) {} |
| Vertex* fHead; |
| Vertex* fTail; |
| void insert(Vertex* v, Vertex* prev, Vertex* next) { |
| list_insert<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, prev, next, &fHead, &fTail); |
| } |
| void append(Vertex* v) { |
| insert(v, fTail, nullptr); |
| } |
| void append(const VertexList& list) { |
| if (!list.fHead) { |
| return; |
| } |
| if (fTail) { |
| fTail->fNext = list.fHead; |
| list.fHead->fPrev = fTail; |
| } else { |
| fHead = list.fHead; |
| } |
| fTail = list.fTail; |
| } |
| void prepend(Vertex* v) { |
| insert(v, nullptr, fHead); |
| } |
| void remove(Vertex* v) { |
| list_remove<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, &fHead, &fTail); |
| } |
| void close() { |
| if (fHead && fTail) { |
| fTail->fNext = fHead; |
| fHead->fPrev = fTail; |
| } |
| } |
| }; |
| |
| // Round to nearest quarter-pixel. This is used for screenspace tessellation. |
| |
| inline void round(SkPoint* p) { |
| p->fX = SkScalarRoundToScalar(p->fX * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); |
| 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(). |
| * Note that an Edge will give occasionally dist() != 0 for its own endpoints (because floating |
| * point). For speed, that case is only tested by the callers that require it (e.g., |
| * rewind_if_necessary()). Edges also handle checking for intersection with other edges. |
| * Currently, this converts the edges to the parametric form, in order to avoid doing a division |
| * until an intersection has been confirmed. This is slightly slower in the "found" case, but |
| * a lot faster in the "not found" case. |
| * |
| * The coefficients of the line equation stored in double precision to avoid catastrphic |
| * cancellation in the isLeftOf() and isRightOf() checks. Using doubles ensures that the result is |
| * correct in float, since it's a polynomial of degree 2. The intersect() function, being |
| * degree 5, is still subject to catastrophic cancellation. We deal with that by assuming its |
| * output may be incorrect, and adjusting the mesh topology to match (see comment at the top of |
| * this file). |
| */ |
| |
| struct Edge { |
| enum class Type { kInner, kOuter, kConnector }; |
| Edge(Vertex* top, Vertex* bottom, int winding, Type type) |
| : fWinding(winding) |
| , fTop(top) |
| , fBottom(bottom) |
| , fType(type) |
| , fLeft(nullptr) |
| , fRight(nullptr) |
| , fPrevEdgeAbove(nullptr) |
| , fNextEdgeAbove(nullptr) |
| , fPrevEdgeBelow(nullptr) |
| , fNextEdgeBelow(nullptr) |
| , fLeftPoly(nullptr) |
| , fRightPoly(nullptr) |
| , fLeftPolyPrev(nullptr) |
| , fLeftPolyNext(nullptr) |
| , fRightPolyPrev(nullptr) |
| , fRightPolyNext(nullptr) |
| , fUsedInLeftPoly(false) |
| , 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). |
| Vertex* fBottom; // The bottom vertex in vertex-sort-order. |
| Type fType; |
| Edge* fLeft; // The linked list of edges in the active edge list. |
| Edge* fRight; // " |
| Edge* fPrevEdgeAbove; // The linked list of edges in the bottom Vertex's "edges above". |
| Edge* fNextEdgeAbove; // " |
| Edge* fPrevEdgeBelow; // The linked list of edges in the top Vertex's "edges below". |
| Edge* fNextEdgeBelow; // " |
| Poly* fLeftPoly; // The Poly to the left of this edge, if any. |
| Poly* fRightPoly; // The Poly to the right of this edge, if any. |
| Edge* fLeftPolyPrev; |
| Edge* fLeftPolyNext; |
| Edge* fRightPolyPrev; |
| Edge* fRightPolyNext; |
| bool fUsedInLeftPoly; |
| bool fUsedInRightPoly; |
| Line fLine; |
| double dist(const SkPoint& p) const { |
| return fLine.dist(p); |
| } |
| bool isRightOf(Vertex* v) const { |
| return fLine.dist(v->fPoint) < 0.0; |
| } |
| bool isLeftOf(Vertex* v) const { |
| return fLine.dist(v->fPoint) > 0.0; |
| } |
| void recompute() { |
| fLine = Line(fTop, fBottom); |
| } |
| bool intersect(const Edge& other, SkPoint* p, uint8_t* alpha = nullptr) { |
| LOG("intersecting %g -> %g with %g -> %g\n", |
| fTop->fID, fBottom->fID, |
| other.fTop->fID, other.fBottom->fID); |
| if (fTop == other.fTop || fBottom == other.fBottom) { |
| return false; |
| } |
| double denom = fLine.fA * other.fLine.fB - fLine.fB * other.fLine.fA; |
| if (denom == 0.0) { |
| return false; |
| } |
| double dx = static_cast<double>(other.fTop->fPoint.fX) - fTop->fPoint.fX; |
| double dy = static_cast<double>(other.fTop->fPoint.fY) - fTop->fPoint.fY; |
| 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) |
| : (sNumer > 0.0 || sNumer < denom || tNumer > 0.0 || tNumer < denom)) { |
| return false; |
| } |
| double s = sNumer / denom; |
| SkASSERT(s >= 0.0 && s <= 1.0); |
| p->fX = SkDoubleToScalar(fTop->fPoint.fX - s * fLine.fB); |
| p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fLine.fA); |
| if (alpha) { |
| if (fType == Type::kConnector) { |
| *alpha = (1.0 - s) * fTop->fAlpha + s * fBottom->fAlpha; |
| } else if (other.fType == Type::kConnector) { |
| double t = tNumer / denom; |
| *alpha = (1.0 - t) * other.fTop->fAlpha + t * other.fBottom->fAlpha; |
| } else if (fType == Type::kOuter && other.fType == Type::kOuter) { |
| *alpha = 0; |
| } else { |
| *alpha = 255; |
| } |
| } |
| return true; |
| } |
| }; |
| |
| struct EdgeList { |
| EdgeList() : fHead(nullptr), fTail(nullptr) {} |
| Edge* fHead; |
| Edge* fTail; |
| void insert(Edge* edge, Edge* prev, Edge* next) { |
| list_insert<Edge, &Edge::fLeft, &Edge::fRight>(edge, prev, next, &fHead, &fTail); |
| } |
| void append(Edge* e) { |
| insert(e, fTail, nullptr); |
| } |
| void remove(Edge* edge) { |
| list_remove<Edge, &Edge::fLeft, &Edge::fRight>(edge, &fHead, &fTail); |
| } |
| void removeAll() { |
| while (fHead) { |
| this->remove(fHead); |
| } |
| } |
| void close() { |
| if (fHead && fTail) { |
| fTail->fRight = fHead; |
| fHead->fLeft = fTail; |
| } |
| } |
| bool contains(Edge* edge) const { |
| return edge->fLeft || edge->fRight || fHead == edge; |
| } |
| }; |
| |
| /***************************************************************************************/ |
| |
| struct Poly { |
| Poly(Vertex* v, int winding) |
| : fFirstVertex(v) |
| , fWinding(winding) |
| , fHead(nullptr) |
| , fTail(nullptr) |
| , fNext(nullptr) |
| , fPartner(nullptr) |
| , fCount(0) |
| { |
| #if LOGGING_ENABLED |
| static int gID = 0; |
| fID = gID++; |
| LOG("*** created Poly %d\n", fID); |
| #endif |
| } |
| typedef enum { kLeft_Side, kRight_Side } Side; |
| struct MonotonePoly { |
| MonotonePoly(Edge* edge, Side side) |
| : fSide(side) |
| , fFirstEdge(nullptr) |
| , fLastEdge(nullptr) |
| , fPrev(nullptr) |
| , fNext(nullptr) { |
| this->addEdge(edge); |
| } |
| Side fSide; |
| Edge* fFirstEdge; |
| Edge* fLastEdge; |
| MonotonePoly* fPrev; |
| MonotonePoly* fNext; |
| void addEdge(Edge* edge) { |
| if (fSide == kRight_Side) { |
| SkASSERT(!edge->fUsedInRightPoly); |
| list_insert<Edge, &Edge::fRightPolyPrev, &Edge::fRightPolyNext>( |
| edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); |
| edge->fUsedInRightPoly = true; |
| } else { |
| SkASSERT(!edge->fUsedInLeftPoly); |
| list_insert<Edge, &Edge::fLeftPolyPrev, &Edge::fLeftPolyNext>( |
| edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); |
| edge->fUsedInLeftPoly = true; |
| } |
| } |
| |
| void* emit(const AAParams* aaParams, void* data) { |
| Edge* e = fFirstEdge; |
| VertexList vertices; |
| vertices.append(e->fTop); |
| int count = 1; |
| while (e != nullptr) { |
| if (kRight_Side == fSide) { |
| vertices.append(e->fBottom); |
| e = e->fRightPolyNext; |
| } else { |
| vertices.prepend(e->fBottom); |
| e = e->fLeftPolyNext; |
| } |
| count++; |
| } |
| Vertex* first = vertices.fHead; |
| Vertex* v = first->fNext; |
| while (v != vertices.fTail) { |
| SkASSERT(v && v->fPrev && v->fNext); |
| Vertex* prev = v->fPrev; |
| Vertex* curr = v; |
| Vertex* next = v->fNext; |
| if (count == 3) { |
| return emit_triangle(prev, curr, next, aaParams, data); |
| } |
| double ax = static_cast<double>(curr->fPoint.fX) - prev->fPoint.fX; |
| double ay = static_cast<double>(curr->fPoint.fY) - prev->fPoint.fY; |
| double bx = static_cast<double>(next->fPoint.fX) - curr->fPoint.fX; |
| double by = static_cast<double>(next->fPoint.fY) - curr->fPoint.fY; |
| if (ax * by - ay * bx >= 0.0) { |
| data = emit_triangle(prev, curr, next, aaParams, data); |
| v->fPrev->fNext = v->fNext; |
| v->fNext->fPrev = v->fPrev; |
| count--; |
| if (v->fPrev == first) { |
| v = v->fNext; |
| } else { |
| v = v->fPrev; |
| } |
| } else { |
| v = v->fNext; |
| } |
| } |
| return data; |
| } |
| }; |
| Poly* addEdge(Edge* e, Side side, SkArenaAlloc& alloc) { |
| LOG("addEdge (%g -> %g) to poly %d, %s side\n", |
| e->fTop->fID, e->fBottom->fID, fID, side == kLeft_Side ? "left" : "right"); |
| Poly* partner = fPartner; |
| Poly* poly = this; |
| if (side == kRight_Side) { |
| if (e->fUsedInRightPoly) { |
| return this; |
| } |
| } else { |
| if (e->fUsedInLeftPoly) { |
| return this; |
| } |
| } |
| if (partner) { |
| fPartner = partner->fPartner = nullptr; |
| } |
| if (!fTail) { |
| fHead = fTail = alloc.make<MonotonePoly>(e, side); |
| fCount += 2; |
| } else if (e->fBottom == fTail->fLastEdge->fBottom) { |
| return poly; |
| } else if (side == fTail->fSide) { |
| fTail->addEdge(e); |
| fCount++; |
| } else { |
| e = alloc.make<Edge>(fTail->fLastEdge->fBottom, e->fBottom, 1, Edge::Type::kInner); |
| fTail->addEdge(e); |
| fCount++; |
| if (partner) { |
| partner->addEdge(e, side, alloc); |
| poly = partner; |
| } else { |
| MonotonePoly* m = alloc.make<MonotonePoly>(e, side); |
| m->fPrev = fTail; |
| fTail->fNext = m; |
| fTail = m; |
| } |
| } |
| return poly; |
| } |
| void* emit(const AAParams* aaParams, void *data) { |
| if (fCount < 3) { |
| return data; |
| } |
| LOG("emit() %d, size %d\n", fID, fCount); |
| for (MonotonePoly* m = fHead; m != nullptr; m = m->fNext) { |
| data = m->emit(aaParams, data); |
| } |
| return data; |
| } |
| Vertex* lastVertex() const { return fTail ? fTail->fLastEdge->fBottom : fFirstVertex; } |
| Vertex* fFirstVertex; |
| int fWinding; |
| MonotonePoly* fHead; |
| MonotonePoly* fTail; |
| Poly* fNext; |
| Poly* fPartner; |
| int fCount; |
| #if LOGGING_ENABLED |
| int fID; |
| #endif |
| }; |
| |
| /***************************************************************************************/ |
| |
| bool coincident(const SkPoint& a, const SkPoint& b) { |
| return a == b; |
| } |
| |
| Poly* new_poly(Poly** head, Vertex* v, int winding, SkArenaAlloc& alloc) { |
| Poly* poly = alloc.make<Poly>(v, winding); |
| poly->fNext = *head; |
| *head = poly; |
| return poly; |
| } |
| |
| void append_point_to_contour(const SkPoint& p, VertexList* contour, SkArenaAlloc& alloc) { |
| Vertex* v = alloc.make<Vertex>(p, 255); |
| #if LOGGING_ENABLED |
| static float gID = 0.0f; |
| v->fID = gID++; |
| #endif |
| contour->append(v); |
| } |
| |
| SkScalar quad_error_at(const SkPoint pts[3], SkScalar t, SkScalar u) { |
| SkQuadCoeff quad(pts); |
| SkPoint p0 = to_point(quad.eval(t - 0.5f * u)); |
| SkPoint mid = to_point(quad.eval(t)); |
| SkPoint p1 = to_point(quad.eval(t + 0.5f * u)); |
| if (!p0.isFinite() || !mid.isFinite() || !p1.isFinite()) { |
| return 0; |
| } |
| return mid.distanceToLineSegmentBetweenSqd(p0, p1); |
| } |
| |
| void append_quadratic_to_contour(const SkPoint pts[3], SkScalar toleranceSqd, VertexList* contour, |
| SkArenaAlloc& alloc) { |
| SkQuadCoeff quad(pts); |
| Sk2s aa = quad.fA * quad.fA; |
| SkScalar denom = 2.0f * (aa[0] + aa[1]); |
| Sk2s ab = quad.fA * quad.fB; |
| SkScalar t = denom ? (-ab[0] - ab[1]) / denom : 0.0f; |
| int nPoints = 1; |
| SkScalar u; |
| // Test possible subdivision values only at the point of maximum curvature. |
| // If it passes the flatness metric there, it'll pass everywhere. |
| for (;;) { |
| u = 1.0f / nPoints; |
| if (quad_error_at(pts, t, u) < toleranceSqd) { |
| break; |
| } |
| nPoints++; |
| } |
| for (int j = 1; j <= nPoints; j++) { |
| append_point_to_contour(to_point(quad.eval(j * u)), contour, alloc); |
| } |
| } |
| |
| void generate_cubic_points(const SkPoint& p0, |
| const SkPoint& p1, |
| const SkPoint& p2, |
| const SkPoint& p3, |
| SkScalar tolSqd, |
| VertexList* contour, |
| int pointsLeft, |
| SkArenaAlloc& alloc) { |
| SkScalar d1 = p1.distanceToLineSegmentBetweenSqd(p0, p3); |
| SkScalar d2 = p2.distanceToLineSegmentBetweenSqd(p0, p3); |
| if (pointsLeft < 2 || (d1 < tolSqd && d2 < tolSqd) || |
| !SkScalarIsFinite(d1) || !SkScalarIsFinite(d2)) { |
| append_point_to_contour(p3, contour, alloc); |
| return; |
| } |
| const SkPoint q[] = { |
| { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, |
| { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, |
| { SkScalarAve(p2.fX, p3.fX), SkScalarAve(p2.fY, p3.fY) } |
| }; |
| const SkPoint r[] = { |
| { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }, |
| { SkScalarAve(q[1].fX, q[2].fX), SkScalarAve(q[1].fY, q[2].fY) } |
| }; |
| const SkPoint s = { SkScalarAve(r[0].fX, r[1].fX), SkScalarAve(r[0].fY, r[1].fY) }; |
| pointsLeft >>= 1; |
| generate_cubic_points(p0, q[0], r[0], s, tolSqd, contour, pointsLeft, alloc); |
| generate_cubic_points(s, r[1], q[2], p3, tolSqd, contour, pointsLeft, alloc); |
| } |
| |
| // Stage 1: convert the input path to a set of linear contours (linked list of Vertices). |
| |
| void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, |
| VertexList* contours, SkArenaAlloc& alloc, bool *isLinear) { |
| SkScalar toleranceSqd = tolerance * tolerance; |
| |
| SkPoint pts[4]; |
| *isLinear = true; |
| VertexList* contour = contours; |
| SkPath::Iter iter(path, false); |
| if (path.isInverseFillType()) { |
| SkPoint quad[4]; |
| clipBounds.toQuad(quad); |
| for (int i = 3; i >= 0; i--) { |
| append_point_to_contour(quad[i], contours, alloc); |
| } |
| contour++; |
| } |
| SkAutoConicToQuads converter; |
| SkPath::Verb verb; |
| while ((verb = iter.next(pts)) != SkPath::kDone_Verb) { |
| switch (verb) { |
| case SkPath::kConic_Verb: { |
| SkScalar weight = iter.conicWeight(); |
| const SkPoint* quadPts = converter.computeQuads(pts, weight, toleranceSqd); |
| for (int i = 0; i < converter.countQuads(); ++i) { |
| append_quadratic_to_contour(quadPts, toleranceSqd, contour, alloc); |
| quadPts += 2; |
| } |
| *isLinear = false; |
| break; |
| } |
| case SkPath::kMove_Verb: |
| if (contour->fHead) { |
| contour++; |
| } |
| append_point_to_contour(pts[0], contour, alloc); |
| break; |
| case SkPath::kLine_Verb: { |
| append_point_to_contour(pts[1], contour, alloc); |
| break; |
| } |
| case SkPath::kQuad_Verb: { |
| append_quadratic_to_contour(pts, toleranceSqd, contour, alloc); |
| *isLinear = false; |
| break; |
| } |
| case SkPath::kCubic_Verb: { |
| int pointsLeft = GrPathUtils::cubicPointCount(pts, tolerance); |
| generate_cubic_points(pts[0], pts[1], pts[2], pts[3], toleranceSqd, contour, |
| pointsLeft, alloc); |
| *isLinear = false; |
| break; |
| } |
| case SkPath::kClose_Verb: |
| case SkPath::kDone_Verb: |
| break; |
| } |
| } |
| } |
| |
| inline bool apply_fill_type(SkPath::FillType fillType, int winding) { |
| switch (fillType) { |
| case SkPath::kWinding_FillType: |
| return winding != 0; |
| case SkPath::kEvenOdd_FillType: |
| return (winding & 1) != 0; |
| case SkPath::kInverseWinding_FillType: |
| return winding == 1; |
| case SkPath::kInverseEvenOdd_FillType: |
| return (winding & 1) == 1; |
| default: |
| SkASSERT(false); |
| return false; |
| } |
| } |
| |
| inline bool apply_fill_type(SkPath::FillType fillType, Poly* poly) { |
| return poly && apply_fill_type(fillType, poly->fWinding); |
| } |
| |
| Edge* new_edge(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkArenaAlloc& alloc) { |
| int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; |
| Vertex* top = winding < 0 ? next : prev; |
| Vertex* bottom = winding < 0 ? prev : next; |
| return alloc.make<Edge>(top, bottom, winding, type); |
| } |
| |
| void remove_edge(Edge* edge, EdgeList* edges) { |
| LOG("removing edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); |
| SkASSERT(edges->contains(edge)); |
| edges->remove(edge); |
| } |
| |
| void insert_edge(Edge* edge, Edge* prev, EdgeList* edges) { |
| LOG("inserting edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); |
| SkASSERT(!edges->contains(edge)); |
| Edge* next = prev ? prev->fRight : edges->fHead; |
| edges->insert(edge, prev, next); |
| } |
| |
| void find_enclosing_edges(Vertex* v, EdgeList* edges, Edge** left, Edge** right) { |
| if (v->fFirstEdgeAbove && v->fLastEdgeAbove) { |
| *left = v->fFirstEdgeAbove->fLeft; |
| *right = v->fLastEdgeAbove->fRight; |
| return; |
| } |
| Edge* next = nullptr; |
| Edge* prev; |
| for (prev = edges->fTail; prev != nullptr; prev = prev->fLeft) { |
| if (prev->isLeftOf(v)) { |
| break; |
| } |
| next = prev; |
| } |
| *left = prev; |
| *right = next; |
| } |
| |
| void insert_edge_above(Edge* edge, Vertex* v, Comparator& c) { |
| if (edge->fTop->fPoint == edge->fBottom->fPoint || |
| c.sweep_lt(edge->fBottom->fPoint, edge->fTop->fPoint)) { |
| return; |
| } |
| LOG("insert edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); |
| Edge* prev = nullptr; |
| Edge* next; |
| for (next = v->fFirstEdgeAbove; next; next = next->fNextEdgeAbove) { |
| if (next->isRightOf(edge->fTop)) { |
| break; |
| } |
| prev = next; |
| } |
| list_insert<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( |
| edge, prev, next, &v->fFirstEdgeAbove, &v->fLastEdgeAbove); |
| } |
| |
| void insert_edge_below(Edge* edge, Vertex* v, Comparator& c) { |
| if (edge->fTop->fPoint == edge->fBottom->fPoint || |
| c.sweep_lt(edge->fBottom->fPoint, edge->fTop->fPoint)) { |
| return; |
| } |
| LOG("insert edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); |
| Edge* prev = nullptr; |
| Edge* next; |
| for (next = v->fFirstEdgeBelow; next; next = next->fNextEdgeBelow) { |
| if (next->isRightOf(edge->fBottom)) { |
| break; |
| } |
| prev = next; |
| } |
| list_insert<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( |
| edge, prev, next, &v->fFirstEdgeBelow, &v->fLastEdgeBelow); |
| } |
| |
| void remove_edge_above(Edge* edge) { |
| LOG("removing edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, |
| edge->fBottom->fID); |
| list_remove<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( |
| edge, &edge->fBottom->fFirstEdgeAbove, &edge->fBottom->fLastEdgeAbove); |
| } |
| |
| void remove_edge_below(Edge* edge) { |
| LOG("removing edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, |
| edge->fTop->fID); |
| list_remove<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( |
| edge, &edge->fTop->fFirstEdgeBelow, &edge->fTop->fLastEdgeBelow); |
| } |
| |
| void disconnect(Edge* edge) |
| { |
| remove_edge_above(edge); |
| remove_edge_below(edge); |
| } |
| |
| void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Vertex** current, Comparator& c); |
| |
| void rewind(EdgeList* activeEdges, Vertex** current, Vertex* dst, Comparator& c) { |
| if (!current || *current == dst || c.sweep_lt((*current)->fPoint, dst->fPoint)) { |
| return; |
| } |
| Vertex* v = *current; |
| LOG("rewinding active edges from vertex %g to vertex %g\n", v->fID, dst->fID); |
| while (v != dst) { |
| v = v->fPrev; |
| for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { |
| remove_edge(e, activeEdges); |
| } |
| Edge* leftEdge = v->fLeftEnclosingEdge; |
| for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { |
| insert_edge(e, leftEdge, activeEdges); |
| leftEdge = e; |
| } |
| } |
| *current = v; |
| } |
| |
| void rewind_if_necessary(Edge* edge, EdgeList* activeEdges, Vertex** current, Comparator& c) { |
| if (!activeEdges || !current) { |
| return; |
| } |
| Vertex* top = edge->fTop; |
| Vertex* bottom = edge->fBottom; |
| if (edge->fLeft) { |
| Vertex* leftTop = edge->fLeft->fTop; |
| Vertex* leftBottom = edge->fLeft->fBottom; |
| if (c.sweep_lt(leftTop->fPoint, top->fPoint) && !edge->fLeft->isLeftOf(top)) { |
| rewind(activeEdges, current, leftTop, c); |
| } else if (c.sweep_lt(top->fPoint, leftTop->fPoint) && !edge->isRightOf(leftTop)) { |
| rewind(activeEdges, current, top, c); |
| } else if (c.sweep_lt(bottom->fPoint, leftBottom->fPoint) && |
| !edge->fLeft->isLeftOf(bottom)) { |
| rewind(activeEdges, current, leftTop, c); |
| } else if (c.sweep_lt(leftBottom->fPoint, bottom->fPoint) && !edge->isRightOf(leftBottom)) { |
| rewind(activeEdges, current, top, c); |
| } |
| } |
| if (edge->fRight) { |
| Vertex* rightTop = edge->fRight->fTop; |
| Vertex* rightBottom = edge->fRight->fBottom; |
| if (c.sweep_lt(rightTop->fPoint, top->fPoint) && !edge->fRight->isRightOf(top)) { |
| rewind(activeEdges, current, rightTop, c); |
| } else if (c.sweep_lt(top->fPoint, rightTop->fPoint) && !edge->isLeftOf(rightTop)) { |
| rewind(activeEdges, current, top, c); |
| } else if (c.sweep_lt(bottom->fPoint, rightBottom->fPoint) && |
| !edge->fRight->isRightOf(bottom)) { |
| rewind(activeEdges, current, rightTop, c); |
| } else if (c.sweep_lt(rightBottom->fPoint, bottom->fPoint) && |
| !edge->isLeftOf(rightBottom)) { |
| rewind(activeEdges, current, top, c); |
| } |
| } |
| } |
| |
| void set_top(Edge* edge, Vertex* v, EdgeList* activeEdges, Vertex** current, Comparator& c) { |
| remove_edge_below(edge); |
| edge->fTop = v; |
| edge->recompute(); |
| insert_edge_below(edge, v, c); |
| rewind_if_necessary(edge, activeEdges, current, c); |
| merge_collinear_edges(edge, activeEdges, current, c); |
| } |
| |
| void set_bottom(Edge* edge, Vertex* v, EdgeList* activeEdges, Vertex** current, Comparator& c) { |
| remove_edge_above(edge); |
| edge->fBottom = v; |
| edge->recompute(); |
| insert_edge_above(edge, v, c); |
| rewind_if_necessary(edge, activeEdges, current, c); |
| merge_collinear_edges(edge, activeEdges, current, c); |
| } |
| |
| void merge_edges_above(Edge* edge, Edge* other, EdgeList* activeEdges, Vertex** current, |
| Comparator& c) { |
| if (coincident(edge->fTop->fPoint, other->fTop->fPoint)) { |
| LOG("merging coincident above edges (%g, %g) -> (%g, %g)\n", |
| edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, |
| edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); |
| rewind(activeEdges, current, edge->fTop, c); |
| other->fWinding += edge->fWinding; |
| disconnect(edge); |
| } else if (c.sweep_lt(edge->fTop->fPoint, other->fTop->fPoint)) { |
| rewind(activeEdges, current, edge->fTop, c); |
| other->fWinding += edge->fWinding; |
| set_bottom(edge, other->fTop, activeEdges, current, c); |
| } else { |
| rewind(activeEdges, current, other->fTop, c); |
| edge->fWinding += other->fWinding; |
| set_bottom(other, edge->fTop, activeEdges, current, c); |
| } |
| } |
| |
| void merge_edges_below(Edge* edge, Edge* other, EdgeList* activeEdges, Vertex** current, |
| Comparator& c) { |
| if (coincident(edge->fBottom->fPoint, other->fBottom->fPoint)) { |
| LOG("merging coincident below edges (%g, %g) -> (%g, %g)\n", |
| edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, |
| edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); |
| rewind(activeEdges, current, edge->fTop, c); |
| other->fWinding += edge->fWinding; |
| disconnect(edge); |
| } else if (c.sweep_lt(edge->fBottom->fPoint, other->fBottom->fPoint)) { |
| rewind(activeEdges, current, other->fTop, c); |
| edge->fWinding += other->fWinding; |
| set_top(other, edge->fBottom, activeEdges, current, c); |
| } else { |
| rewind(activeEdges, current, edge->fTop, c); |
| other->fWinding += edge->fWinding; |
| set_top(edge, other->fBottom, activeEdges, current, c); |
| } |
| } |
| |
| void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Vertex** current, Comparator& c) { |
| for (;;) { |
| if (edge->fPrevEdgeAbove && (edge->fTop == edge->fPrevEdgeAbove->fTop || |
| !edge->fPrevEdgeAbove->isLeftOf(edge->fTop))) { |
| merge_edges_above(edge, edge->fPrevEdgeAbove, activeEdges, current, c); |
| } else if (edge->fNextEdgeAbove && (edge->fTop == edge->fNextEdgeAbove->fTop || |
| !edge->isLeftOf(edge->fNextEdgeAbove->fTop))) { |
| merge_edges_above(edge, edge->fNextEdgeAbove, activeEdges, current, c); |
| } else if (edge->fPrevEdgeBelow && (edge->fBottom == edge->fPrevEdgeBelow->fBottom || |
| !edge->fPrevEdgeBelow->isLeftOf(edge->fBottom))) { |
| merge_edges_below(edge, edge->fPrevEdgeBelow, activeEdges, current, c); |
| } else if (edge->fNextEdgeBelow && (edge->fBottom == edge->fNextEdgeBelow->fBottom || |
| !edge->isLeftOf(edge->fNextEdgeBelow->fBottom))) { |
| merge_edges_below(edge, edge->fNextEdgeBelow, activeEdges, current, c); |
| } else { |
| break; |
| } |
| } |
| SkASSERT(!edge->fPrevEdgeAbove || edge->fPrevEdgeAbove->isLeftOf(edge->fTop)); |
| SkASSERT(!edge->fPrevEdgeBelow || edge->fPrevEdgeBelow->isLeftOf(edge->fBottom)); |
| SkASSERT(!edge->fNextEdgeAbove || edge->fNextEdgeAbove->isRightOf(edge->fTop)); |
| SkASSERT(!edge->fNextEdgeBelow || edge->fNextEdgeBelow->isRightOf(edge->fBottom)); |
| } |
| |
| void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Vertex** current, Comparator& c, |
| SkArenaAlloc& alloc) { |
| if (v == edge->fTop || v == edge->fBottom) { |
| return; |
| } |
| LOG("splitting edge (%g -> %g) at vertex %g (%g, %g)\n", |
| edge->fTop->fID, edge->fBottom->fID, |
| v->fID, v->fPoint.fX, v->fPoint.fY); |
| Vertex* top; |
| Vertex* bottom; |
| if (c.sweep_lt(v->fPoint, edge->fTop->fPoint)) { |
| top = v; |
| bottom = edge->fTop; |
| set_top(edge, v, activeEdges, current, c); |
| } else if (c.sweep_lt(edge->fBottom->fPoint, v->fPoint)) { |
| top = edge->fBottom; |
| bottom = v; |
| set_bottom(edge, v, activeEdges, current, c); |
| } else { |
| top = v; |
| bottom = edge->fBottom; |
| set_bottom(edge, v, activeEdges, current, c); |
| } |
| Edge* newEdge = alloc.make<Edge>(top, bottom, edge->fWinding, edge->fType); |
| insert_edge_below(newEdge, top, c); |
| insert_edge_above(newEdge, bottom, c); |
| merge_collinear_edges(newEdge, activeEdges, current, c); |
| } |
| |
| Edge* connect(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkArenaAlloc& alloc, |
| int winding_scale = 1) { |
| Edge* edge = new_edge(prev, next, type, c, alloc); |
| insert_edge_below(edge, edge->fTop, c); |
| insert_edge_above(edge, edge->fBottom, c); |
| edge->fWinding *= winding_scale; |
| merge_collinear_edges(edge, nullptr, nullptr, c); |
| return edge; |
| } |
| |
| void merge_vertices(Vertex* src, Vertex* dst, VertexList* mesh, Comparator& c, |
| SkArenaAlloc& alloc) { |
| LOG("found coincident verts at %g, %g; merging %g into %g\n", src->fPoint.fX, src->fPoint.fY, |
| src->fID, dst->fID); |
| dst->fAlpha = SkTMax(src->fAlpha, dst->fAlpha); |
| if (src->fPartner) { |
| src->fPartner->fPartner = dst; |
| } |
| for (Edge* edge = src->fFirstEdgeAbove; edge;) { |
| Edge* next = edge->fNextEdgeAbove; |
| set_bottom(edge, dst, nullptr, nullptr, c); |
| edge = next; |
| } |
| for (Edge* edge = src->fFirstEdgeBelow; edge;) { |
| Edge* next = edge->fNextEdgeBelow; |
| set_top(edge, dst, nullptr, nullptr, c); |
| edge = next; |
| } |
| mesh->remove(src); |
| } |
| |
| uint8_t max_edge_alpha(Edge* a, Edge* b) { |
| if (a->fType == Edge::Type::kInner || b->fType == Edge::Type::kInner) { |
| return 255; |
| } else if (a->fType == Edge::Type::kOuter && b->fType == Edge::Type::kOuter) { |
| return 0; |
| } else { |
| return SkTMax(SkTMax(a->fTop->fAlpha, a->fBottom->fAlpha), |
| SkTMax(b->fTop->fAlpha, b->fBottom->fAlpha)); |
| } |
| } |
| |
| bool check_for_intersection(Edge* edge, Edge* other, EdgeList* activeEdges, Vertex** current, |
| VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { |
| if (!edge || !other) { |
| return false; |
| } |
| SkPoint p; |
| uint8_t alpha; |
| if (edge->intersect(*other, &p, &alpha) && p.isFinite()) { |
| Vertex* v; |
| LOG("found intersection, pt is %g, %g\n", p.fX, p.fY); |
| Vertex* top = *current; |
| // If the intersection point is above the current vertex, rewind to the vertex above the |
| // intersection. |
| while (top && c.sweep_lt(p, top->fPoint)) { |
| top = top->fPrev; |
| } |
| if (p == edge->fTop->fPoint) { |
| v = edge->fTop; |
| } else if (p == edge->fBottom->fPoint) { |
| v = edge->fBottom; |
| } else if (p == other->fTop->fPoint) { |
| v = other->fTop; |
| } else if (p == other->fBottom->fPoint) { |
| v = other->fBottom; |
| } else { |
| Vertex* prevV = top; |
| Vertex* nextV = top ? top->fNext : mesh->fHead; |
| while (nextV && c.sweep_lt(nextV->fPoint, p)) { |
| prevV = nextV; |
| nextV = nextV->fNext; |
| } |
| if (prevV && coincident(prevV->fPoint, p)) { |
| v = prevV; |
| } else if (nextV && coincident(nextV->fPoint, p)) { |
| v = nextV; |
| } else { |
| v = alloc.make<Vertex>(p, alpha); |
| #if LOGGING_ENABLED |
| if (!prevV) { |
| v->fID = mesh->fHead->fID - 1.0f; |
| } else if (!nextV) { |
| v->fID = mesh->fTail->fID + 1.0f; |
| } else { |
| v->fID = (prevV->fID + nextV->fID) * 0.5f; |
| } |
| #endif |
| mesh->insert(v, prevV, nextV); |
| } |
| } |
| rewind(activeEdges, current, top ? top : v, c); |
| split_edge(edge, v, activeEdges, current, c, alloc); |
| split_edge(other, v, activeEdges, current, c, alloc); |
| v->fAlpha = SkTMax(v->fAlpha, alpha); |
| return true; |
| } |
| return false; |
| } |
| |
| void sanitize_contours(VertexList* contours, int contourCnt, bool approximate) { |
| for (VertexList* contour = contours; contourCnt > 0; --contourCnt, ++contour) { |
| SkASSERT(contour->fHead); |
| Vertex* prev = contour->fTail; |
| if (approximate) { |
| round(&prev->fPoint); |
| } |
| for (Vertex* v = contour->fHead; v;) { |
| if (approximate) { |
| round(&v->fPoint); |
| } |
| Vertex* next = v->fNext; |
| if (coincident(prev->fPoint, v->fPoint)) { |
| LOG("vertex %g,%g coincident; removing\n", v->fPoint.fX, v->fPoint.fY); |
| contour->remove(v); |
| } |
| prev = v; |
| v = next; |
| } |
| } |
| } |
| |
| void merge_coincident_vertices(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { |
| if (!mesh->fHead) { |
| return; |
| } |
| for (Vertex* v = mesh->fHead->fNext; v != nullptr; v = v->fNext) { |
| if (c.sweep_lt(v->fPoint, v->fPrev->fPoint)) { |
| v->fPoint = v->fPrev->fPoint; |
| } |
| if (coincident(v->fPrev->fPoint, v->fPoint)) { |
| merge_vertices(v->fPrev, v, mesh, c, alloc); |
| } |
| } |
| } |
| |
| // Stage 2: convert the contours to a mesh of edges connecting the vertices. |
| |
| void build_edges(VertexList* contours, int contourCnt, VertexList* mesh, Comparator& c, |
| SkArenaAlloc& alloc) { |
| for (VertexList* contour = contours; contourCnt > 0; --contourCnt, ++contour) { |
| Vertex* prev = contour->fTail; |
| for (Vertex* v = contour->fHead; v;) { |
| Vertex* next = v->fNext; |
| connect(prev, v, Edge::Type::kInner, c, alloc); |
| mesh->append(v); |
| prev = v; |
| v = next; |
| } |
| } |
| } |
| |
| void connect_partners(VertexList* outerVertices, Comparator& c, SkArenaAlloc& alloc) { |
| for (Vertex* outer = outerVertices->fHead; outer; outer = outer->fNext) { |
| if (Vertex* inner = outer->fPartner) { |
| // Connector edges get zero winding, since they're only structural (i.e., to ensure |
| // no 0-0-0 alpha triangles are produced), and shouldn't affect the poly winding number. |
| connect(outer, inner, Edge::Type::kConnector, c, alloc, 0); |
| inner->fPartner = outer->fPartner = nullptr; |
| } |
| } |
| } |
| |
| template <CompareFunc sweep_lt> |
| void sorted_merge(VertexList* front, VertexList* back, VertexList* result) { |
| Vertex* a = front->fHead; |
| Vertex* b = back->fHead; |
| while (a && b) { |
| if (sweep_lt(a->fPoint, b->fPoint)) { |
| front->remove(a); |
| result->append(a); |
| a = front->fHead; |
| } else { |
| back->remove(b); |
| result->append(b); |
| b = back->fHead; |
| } |
| } |
| result->append(*front); |
| result->append(*back); |
| } |
| |
| void sorted_merge(VertexList* front, VertexList* back, VertexList* result, Comparator& c) { |
| if (c.fDirection == Comparator::Direction::kHorizontal) { |
| sorted_merge<sweep_lt_horiz>(front, back, result); |
| } else { |
| sorted_merge<sweep_lt_vert>(front, back, result); |
| } |
| #if LOGGING_ENABLED |
| float id = 0.0f; |
| for (Vertex* v = result->fHead; v; v = v->fNext) { |
| v->fID = id++; |
| } |
| #endif |
| } |
| |
| // Stage 3: sort the vertices by increasing sweep direction. |
| |
| template <CompareFunc sweep_lt> |
| void merge_sort(VertexList* vertices) { |
| Vertex* slow = vertices->fHead; |
| if (!slow) { |
| return; |
| } |
| Vertex* fast = slow->fNext; |
| if (!fast) { |
| return; |
| } |
| do { |
| fast = fast->fNext; |
| if (fast) { |
| fast = fast->fNext; |
| slow = slow->fNext; |
| } |
| } while (fast); |
| VertexList front(vertices->fHead, slow); |
| VertexList back(slow->fNext, vertices->fTail); |
| front.fTail->fNext = back.fHead->fPrev = nullptr; |
| |
| merge_sort<sweep_lt>(&front); |
| merge_sort<sweep_lt>(&back); |
| |
| vertices->fHead = vertices->fTail = nullptr; |
| sorted_merge<sweep_lt>(&front, &back, vertices); |
| } |
| |
| // Stage 4: Simplify the mesh by inserting new vertices at intersecting edges. |
| |
| void simplify(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { |
| LOG("simplifying complex polygons\n"); |
| EdgeList activeEdges; |
| for (Vertex* v = mesh->fHead; v != nullptr; v = v->fNext) { |
| if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { |
| continue; |
| } |
| Edge* leftEnclosingEdge; |
| Edge* rightEnclosingEdge; |
| bool restartChecks; |
| do { |
| LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); |
| restartChecks = false; |
| find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); |
| if (rightEnclosingEdge && !rightEnclosingEdge->isRightOf(v)) { |
| split_edge(rightEnclosingEdge, v, &activeEdges, &v, c, alloc); |
| restartChecks = true; |
| continue; |
| } |
| SkASSERT(!rightEnclosingEdge || rightEnclosingEdge->isRightOf(v)); |
| v->fLeftEnclosingEdge = leftEnclosingEdge; |
| v->fRightEnclosingEdge = rightEnclosingEdge; |
| if (v->fFirstEdgeBelow) { |
| for (Edge* edge = v->fFirstEdgeBelow; edge; edge = edge->fNextEdgeBelow) { |
| if (check_for_intersection(edge, leftEnclosingEdge, &activeEdges, &v, mesh, c, |
| alloc)) { |
| restartChecks = true; |
| break; |
| } |
| if (check_for_intersection(edge, rightEnclosingEdge, &activeEdges, &v, mesh, c, |
| alloc)) { |
| restartChecks = true; |
| break; |
| } |
| } |
| } else { |
| if (check_for_intersection(leftEnclosingEdge, rightEnclosingEdge, |
| &activeEdges, &v, mesh, c, alloc)) { |
| restartChecks = true; |
| } |
| |
| } |
| } while (restartChecks); |
| if (v->fAlpha == 0) { |
| if ((leftEnclosingEdge && leftEnclosingEdge->fWinding < 0) && |
| (rightEnclosingEdge && rightEnclosingEdge->fWinding > 0)) { |
| v->fAlpha = max_edge_alpha(leftEnclosingEdge, rightEnclosingEdge); |
| } |
| } |
| for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { |
| remove_edge(e, &activeEdges); |
| } |
| Edge* leftEdge = leftEnclosingEdge; |
| for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { |
| insert_edge(e, leftEdge, &activeEdges); |
| leftEdge = e; |
| } |
| } |
| } |
| |
| // This is a stripped-down version of simplify() (the Bentley-Ottmann algorithm) that |
| // early-returns true on the first found intersection, false if none. |
| bool is_complex(const VertexList& vertices) { |
| LOG("testing polygon complexity\n"); |
| EdgeList activeEdges; |
| for (Vertex* v = vertices.fHead; v != nullptr; v = v->fNext) { |
| if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { |
| continue; |
| } |
| Edge* leftEnclosingEdge; |
| Edge* rightEnclosingEdge; |
| find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); |
| SkPoint dummy; |
| if (v->fFirstEdgeBelow) { |
| for (Edge* edge = v->fFirstEdgeBelow; edge; edge = edge->fNextEdgeBelow) { |
| if (edge && leftEnclosingEdge && edge->intersect(*leftEnclosingEdge, &dummy)) { |
| activeEdges.removeAll(); |
| return true; |
| } |
| if (edge && rightEnclosingEdge && edge->intersect(*rightEnclosingEdge, &dummy)) { |
| activeEdges.removeAll(); |
| return true; |
| } |
| } |
| } else if (leftEnclosingEdge && rightEnclosingEdge && |
| leftEnclosingEdge->intersect(*rightEnclosingEdge, &dummy)) { |
| activeEdges.removeAll(); |
| return true; |
| } |
| for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { |
| remove_edge(e, &activeEdges); |
| } |
| Edge* leftEdge = leftEnclosingEdge; |
| for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { |
| insert_edge(e, leftEdge, &activeEdges); |
| leftEdge = e; |
| } |
| } |
| activeEdges.removeAll(); |
| return false; |
| } |
| |
| // Stage 5: Tessellate the simplified mesh into monotone polygons. |
| |
| Poly* tessellate(const VertexList& vertices, SkArenaAlloc& alloc) { |
| LOG("tessellating simple polygons\n"); |
| EdgeList activeEdges; |
| Poly* polys = nullptr; |
| for (Vertex* v = vertices.fHead; v != nullptr; v = v->fNext) { |
| if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { |
| continue; |
| } |
| #if LOGGING_ENABLED |
| LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); |
| #endif |
| Edge* leftEnclosingEdge; |
| Edge* rightEnclosingEdge; |
| find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); |
| Poly* leftPoly; |
| Poly* rightPoly; |
| if (v->fFirstEdgeAbove) { |
| leftPoly = v->fFirstEdgeAbove->fLeftPoly; |
| rightPoly = v->fLastEdgeAbove->fRightPoly; |
| } else { |
| leftPoly = leftEnclosingEdge ? leftEnclosingEdge->fRightPoly : nullptr; |
| rightPoly = rightEnclosingEdge ? rightEnclosingEdge->fLeftPoly : nullptr; |
| } |
| #if LOGGING_ENABLED |
| LOG("edges above:\n"); |
| for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { |
| LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, |
| e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); |
| } |
| LOG("edges below:\n"); |
| for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { |
| LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, |
| e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); |
| } |
| #endif |
| if (v->fFirstEdgeAbove) { |
| if (leftPoly) { |
| leftPoly = leftPoly->addEdge(v->fFirstEdgeAbove, Poly::kRight_Side, alloc); |
| } |
| if (rightPoly) { |
| rightPoly = rightPoly->addEdge(v->fLastEdgeAbove, Poly::kLeft_Side, alloc); |
| } |
| for (Edge* e = v->fFirstEdgeAbove; e != v->fLastEdgeAbove; e = e->fNextEdgeAbove) { |
| Edge* rightEdge = e->fNextEdgeAbove; |
| remove_edge(e, &activeEdges); |
| if (e->fRightPoly) { |
| e->fRightPoly->addEdge(e, Poly::kLeft_Side, alloc); |
| } |
| if (rightEdge->fLeftPoly && rightEdge->fLeftPoly != e->fRightPoly) { |
| rightEdge->fLeftPoly->addEdge(e, Poly::kRight_Side, alloc); |
| } |
| } |
| remove_edge(v->fLastEdgeAbove, &activeEdges); |
| if (!v->fFirstEdgeBelow) { |
| if (leftPoly && rightPoly && leftPoly != rightPoly) { |
| SkASSERT(leftPoly->fPartner == nullptr && rightPoly->fPartner == nullptr); |
| rightPoly->fPartner = leftPoly; |
| leftPoly->fPartner = rightPoly; |
| } |
| } |
| } |
| if (v->fFirstEdgeBelow) { |
| if (!v->fFirstEdgeAbove) { |
| if (leftPoly && rightPoly) { |
| if (leftPoly == rightPoly) { |
| if (leftPoly->fTail && leftPoly->fTail->fSide == Poly::kLeft_Side) { |
| leftPoly = new_poly(&polys, leftPoly->lastVertex(), |
| leftPoly->fWinding, alloc); |
| leftEnclosingEdge->fRightPoly = leftPoly; |
| } else { |
| rightPoly = new_poly(&polys, rightPoly->lastVertex(), |
| rightPoly->fWinding, alloc); |
| rightEnclosingEdge->fLeftPoly = rightPoly; |
| } |
| } |
| Edge* join = alloc.make<Edge>(leftPoly->lastVertex(), v, 1, Edge::Type::kInner); |
| leftPoly = leftPoly->addEdge(join, Poly::kRight_Side, alloc); |
| rightPoly = rightPoly->addEdge(join, Poly::kLeft_Side, alloc); |
| } |
| } |
| Edge* leftEdge = v->fFirstEdgeBelow; |
| leftEdge->fLeftPoly = leftPoly; |
| insert_edge(leftEdge, leftEnclosingEdge, &activeEdges); |
| for (Edge* rightEdge = leftEdge->fNextEdgeBelow; rightEdge; |
| rightEdge = rightEdge->fNextEdgeBelow) { |
| insert_edge(rightEdge, leftEdge, &activeEdges); |
| int winding = leftEdge->fLeftPoly ? leftEdge->fLeftPoly->fWinding : 0; |
| winding += leftEdge->fWinding; |
| if (winding != 0) { |
| Poly* poly = new_poly(&polys, v, winding, alloc); |
| leftEdge->fRightPoly = rightEdge->fLeftPoly = poly; |
| } |
| leftEdge = rightEdge; |
| } |
| v->fLastEdgeBelow->fRightPoly = rightPoly; |
| } |
| #if LOGGING_ENABLED |
| LOG("\nactive edges:\n"); |
| for (Edge* e = activeEdges.fHead; e != nullptr; e = e->fRight) { |
| LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, |
| e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); |
| } |
| #endif |
| } |
| return polys; |
| } |
| |
| void remove_non_boundary_edges(const VertexList& mesh, SkPath::FillType fillType, |
| SkArenaAlloc& alloc) { |
| LOG("removing non-boundary edges\n"); |
| EdgeList activeEdges; |
| for (Vertex* v = mesh.fHead; v != nullptr; v = v->fNext) { |
| if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { |
| continue; |
| } |
| Edge* leftEnclosingEdge; |
| Edge* rightEnclosingEdge; |
| find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); |
| bool prevFilled = leftEnclosingEdge && |
| apply_fill_type(fillType, leftEnclosingEdge->fWinding); |
| for (Edge* e = v->fFirstEdgeAbove; e;) { |
| Edge* next = e->fNextEdgeAbove; |
| remove_edge(e, &activeEdges); |
| bool filled = apply_fill_type(fillType, e->fWinding); |
| if (filled == prevFilled) { |
| disconnect(e); |
| } |
| prevFilled = filled; |
| e = next; |
| } |
| Edge* prev = leftEnclosingEdge; |
| for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { |
| if (prev) { |
| e->fWinding += prev->fWinding; |
| } |
| insert_edge(e, prev, &activeEdges); |
| prev = e; |
| } |
| } |
| } |
| |
| // Note: this is the normal to the edge, but not necessarily unit length. |
| void get_edge_normal(const Edge* e, SkVector* normal) { |
| normal->set(SkDoubleToScalar(e->fLine.fA) * e->fWinding, |
| SkDoubleToScalar(e->fLine.fB) * e->fWinding); |
| } |
| |
| // Stage 5c: detect and remove "pointy" vertices whose edge normals point in opposite directions |
| // and whose adjacent vertices are less than a quarter pixel from an edge. These are guaranteed to |
| // invert on stroking. |
| |
| void simplify_boundary(EdgeList* boundary, Comparator& c, SkArenaAlloc& alloc) { |
| Edge* prevEdge = boundary->fTail; |
| SkVector prevNormal; |
| get_edge_normal(prevEdge, &prevNormal); |
| for (Edge* e = boundary->fHead; e != nullptr;) { |
| Vertex* prev = prevEdge->fWinding == 1 ? prevEdge->fTop : prevEdge->fBottom; |
| Vertex* next = e->fWinding == 1 ? e->fBottom : e->fTop; |
| double dist = e->dist(prev->fPoint); |
| SkVector normal; |
| get_edge_normal(e, &normal); |
| double denom = 0.0625f * e->fLine.magSq(); |
| if (prevNormal.dot(normal) < 0.0 && (dist * dist) <= denom) { |
| Edge* join = new_edge(prev, next, Edge::Type::kInner, c, alloc); |
| insert_edge(join, e, boundary); |
| remove_edge(prevEdge, boundary); |
| remove_edge(e, boundary); |
| if (join->fLeft && join->fRight) { |
| prevEdge = join->fLeft; |
| e = join; |
| } else { |
| prevEdge = boundary->fTail; |
| e = boundary->fHead; // join->fLeft ? join->fLeft : join; |
| } |
| get_edge_normal(prevEdge, &prevNormal); |
| } else { |
| prevEdge = e; |
| prevNormal = normal; |
| e = e->fRight; |
| } |
| } |
| } |
| |
| void fix_inversions(Vertex* prev, Vertex* next, Edge* prevBisector, Edge* nextBisector, |
| Edge* prevEdge, Comparator& c) { |
| if (!prev || !next) { |
| return; |
| } |
| int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; |
| SkPoint p; |
| uint8_t alpha; |
| if (winding != prevEdge->fWinding && prevBisector->intersect(*nextBisector, &p, &alpha)) { |
| prev->fPoint = next->fPoint = p; |
| prev->fAlpha = next->fAlpha = alpha; |
| } |
| } |
| |
| // Stage 5d: Displace edges by half a pixel inward and outward along their normals. Intersect to |
| // find new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a |
| // new antialiased mesh from those vertices. |
| |
| void stroke_boundary(EdgeList* boundary, VertexList* innerMesh, VertexList* outerMesh, |
| Comparator& c, SkArenaAlloc& alloc) { |
| // A boundary with fewer than 3 edges is degenerate. |
| if (!boundary->fHead || !boundary->fHead->fRight || !boundary->fHead->fRight->fRight) { |
| return; |
| } |
| Edge* prevEdge = boundary->fTail; |
| float radius = 0.5f; |
| double offset = radius * sqrt(prevEdge->fLine.magSq()) * prevEdge->fWinding; |
| Line prevInner(prevEdge->fLine); |
| prevInner.fC -= offset; |
| Line prevOuter(prevEdge->fLine); |
| prevOuter.fC += offset; |
| VertexList innerVertices; |
| VertexList outerVertices; |
| Edge* prevBisector = nullptr; |
| for (Edge* e = boundary->fHead; e != nullptr; e = e->fRight) { |
| double offset = radius * sqrt(e->fLine.magSq()) * e->fWinding; |
| Line inner(e->fLine); |
| inner.fC -= offset; |
| Line outer(e->fLine); |
| outer.fC += offset; |
| SkPoint innerPoint, outerPoint; |
| if (prevInner.intersect(inner, &innerPoint) && |
| prevOuter.intersect(outer, &outerPoint)) { |
| Vertex* innerVertex = alloc.make<Vertex>(innerPoint, 255); |
| Vertex* outerVertex = alloc.make<Vertex>(outerPoint, 0); |
| Edge* bisector = new_edge(outerVertex, innerVertex, Edge::Type::kConnector, c, alloc); |
| fix_inversions(innerVertices.fTail, innerVertex, prevBisector, bisector, prevEdge, c); |
| fix_inversions(outerVertices.fTail, outerVertex, prevBisector, bisector, prevEdge, c); |
| innerVertex->fPartner = outerVertex; |
| outerVertex->fPartner = innerVertex; |
| innerVertices.append(innerVertex); |
| outerVertices.append(outerVertex); |
| prevBisector = bisector; |
| } |
| prevInner = inner; |
| prevOuter = outer; |
| prevEdge = e; |
| } |
| |
| Vertex* innerVertex = innerVertices.fHead; |
| Vertex* outerVertex = outerVertices.fHead; |
| if (!innerVertex || !outerVertex) { |
| return; |
| } |
| Edge* bisector = new_edge(outerVertices.fHead, innerVertices.fHead, Edge::Type::kConnector, c, |
| alloc); |
| fix_inversions(innerVertices.fTail, innerVertices.fHead, prevBisector, bisector, prevEdge, c); |
| fix_inversions(outerVertices.fTail, outerVertices.fHead, prevBisector, bisector, prevEdge, c); |
| Vertex* prevInnerVertex = innerVertices.fTail; |
| Vertex* prevOuterVertex = outerVertices.fTail; |
| while (innerVertex && outerVertex) { |
| // Connect vertices into a quad mesh. Outer edges get default (1) winding. |
| // Inner edges get -2 winding. This ensures that the interior is always filled |
| // (-1 winding number for normal cases, 3 for thin features where the interior inverts). |
| connect(prevOuterVertex, outerVertex, Edge::Type::kOuter, c, alloc); |
| connect(prevInnerVertex, innerVertex, Edge::Type::kInner, c, alloc, -2); |
| prevInnerVertex = innerVertex; |
| prevOuterVertex = outerVertex; |
| innerVertex = innerVertex->fNext; |
| outerVertex = outerVertex->fNext; |
| } |
| innerMesh->append(innerVertices); |
| outerMesh->append(outerVertices); |
| } |
| |
| void extract_boundary(EdgeList* boundary, Edge* e, SkPath::FillType fillType, SkArenaAlloc& alloc) { |
| bool down = apply_fill_type(fillType, e->fWinding); |
| while (e) { |
| e->fWinding = down ? 1 : -1; |
| Edge* next; |
| boundary->append(e); |
| if (down) { |
| // Find outgoing edge, in clockwise order. |
| if ((next = e->fNextEdgeAbove)) { |
| down = false; |
| } else if ((next = e->fBottom->fLastEdgeBelow)) { |
| down = true; |
| } else if ((next = e->fPrevEdgeAbove)) { |
| down = false; |
| } |
| } else { |
| // Find outgoing edge, in counter-clockwise order. |
| if ((next = e->fPrevEdgeBelow)) { |
| down = true; |
| } else if ((next = e->fTop->fFirstEdgeAbove)) { |
| down = false; |
| } else if ((next = e->fNextEdgeBelow)) { |
| down = true; |
| } |
| } |
| disconnect(e); |
| e = next; |
| } |
| } |
| |
| // Stage 5b: Extract boundaries from mesh, simplify and stroke them into a new mesh. |
| |
| void extract_boundaries(const VertexList& inMesh, VertexList* innerVertices, |
| VertexList* outerVertices, SkPath::FillType fillType, |
| Comparator& c, SkArenaAlloc& alloc) { |
| remove_non_boundary_edges(inMesh, fillType, alloc); |
| for (Vertex* v = inMesh.fHead; v; v = v->fNext) { |
| while (v->fFirstEdgeBelow) { |
| EdgeList boundary; |
| extract_boundary(&boundary, v->fFirstEdgeBelow, fillType, alloc); |
| simplify_boundary(&boundary, c, alloc); |
| stroke_boundary(&boundary, innerVertices, outerVertices, c, alloc); |
| } |
| } |
| } |
| |
| // This is a driver function that calls stages 2-5 in turn. |
| |
| void contours_to_mesh(VertexList* contours, int contourCnt, bool antialias, |
| VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { |
| #if LOGGING_ENABLED |
| for (int i = 0; i < contourCnt; ++i) { |
| Vertex* v = contours[i].fHead; |
| SkASSERT(v); |
| LOG("path.moveTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); |
| for (v = v->fNext; v; v = v->fNext) { |
| LOG("path.lineTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); |
| } |
| } |
| #endif |
| sanitize_contours(contours, contourCnt, antialias); |
| build_edges(contours, contourCnt, mesh, c, alloc); |
| } |
| |
| void sort_mesh(VertexList* vertices, Comparator& c, SkArenaAlloc& alloc) { |
| if (!vertices || !vertices->fHead) { |
| return; |
| } |
| |
| // Sort vertices in Y (secondarily in X). |
| if (c.fDirection == Comparator::Direction::kHorizontal) { |
| merge_sort<sweep_lt_horiz>(vertices); |
| } else { |
| merge_sort<sweep_lt_vert>(vertices); |
| } |
| #if LOGGING_ENABLED |
| for (Vertex* v = vertices->fHead; v != nullptr; v = v->fNext) { |
| static float gID = 0.0f; |
| v->fID = gID++; |
| } |
| #endif |
| } |
| |
| Poly* contours_to_polys(VertexList* contours, int contourCnt, SkPath::FillType fillType, |
| const SkRect& pathBounds, bool antialias, VertexList* outerMesh, |
| SkArenaAlloc& alloc) { |
| Comparator c(pathBounds.width() > pathBounds.height() ? Comparator::Direction::kHorizontal |
| : Comparator::Direction::kVertical); |
| VertexList mesh; |
| contours_to_mesh(contours, contourCnt, antialias, &mesh, c, alloc); |
| sort_mesh(&mesh, c, alloc); |
| merge_coincident_vertices(&mesh, c, alloc); |
| simplify(&mesh, c, alloc); |
| if (antialias) { |
| VertexList innerMesh; |
| extract_boundaries(mesh, &innerMesh, outerMesh, fillType, c, alloc); |
| sort_mesh(&innerMesh, c, alloc); |
| sort_mesh(outerMesh, c, alloc); |
| if (is_complex(innerMesh) || is_complex(*outerMesh)) { |
| LOG("found complex mesh; taking slow path\n"); |
| VertexList aaMesh; |
| connect_partners(outerMesh, c, alloc); |
| sorted_merge(&innerMesh, outerMesh, &aaMesh, c); |
| merge_coincident_vertices(&aaMesh, c, alloc); |
| simplify(&aaMesh, c, alloc); |
| outerMesh->fHead = outerMesh->fTail = nullptr; |
| return tessellate(aaMesh, alloc); |
| } else { |
| LOG("no complex polygons; taking fast path\n"); |
| merge_coincident_vertices(&innerMesh, c, alloc); |
| return tessellate(innerMesh, alloc); |
| } |
| } else { |
| return tessellate(mesh, alloc); |
| } |
| } |
| |
| // Stage 6: Triangulate the monotone polygons into a vertex buffer. |
| void* polys_to_triangles(Poly* polys, SkPath::FillType fillType, const AAParams* aaParams, |
| void* data) { |
| for (Poly* poly = polys; poly; poly = poly->fNext) { |
| if (apply_fill_type(fillType, poly)) { |
| data = poly->emit(aaParams, data); |
| } |
| } |
| return data; |
| } |
| |
| Poly* path_to_polys(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, |
| int contourCnt, SkArenaAlloc& alloc, bool antialias, bool* isLinear, |
| VertexList* outerMesh) { |
| SkPath::FillType fillType = path.getFillType(); |
| if (SkPath::IsInverseFillType(fillType)) { |
| contourCnt++; |
| } |
| std::unique_ptr<VertexList[]> contours(new VertexList[contourCnt]); |
| |
| path_to_contours(path, tolerance, clipBounds, contours.get(), alloc, isLinear); |
| return contours_to_polys(contours.get(), contourCnt, path.getFillType(), path.getBounds(), |
| antialias, outerMesh, alloc); |
| } |
| |
| int get_contour_count(const SkPath& path, SkScalar tolerance) { |
| int contourCnt; |
| int maxPts = GrPathUtils::worstCasePointCount(path, &contourCnt, tolerance); |
| if (maxPts <= 0) { |
| return 0; |
| } |
| if (maxPts > ((int)SK_MaxU16 + 1)) { |
| SkDebugf("Path not rendered, too many verts (%d)\n", maxPts); |
| return 0; |
| } |
| return contourCnt; |
| } |
| |
| int count_points(Poly* polys, SkPath::FillType fillType) { |
| int count = 0; |
| for (Poly* poly = polys; poly; poly = poly->fNext) { |
| if (apply_fill_type(fillType, poly) && poly->fCount >= 3) { |
| count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3); |
| } |
| } |
| return count; |
| } |
| |
| int count_outer_mesh_points(const VertexList& outerMesh) { |
| int count = 0; |
| for (Vertex* v = outerMesh.fHead; v; v = v->fNext) { |
| for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { |
| count += TESSELLATOR_WIREFRAME ? 12 : 6; |
| } |
| } |
| return count; |
| } |
| |
| void* outer_mesh_to_triangles(const VertexList& outerMesh, const AAParams* aaParams, void* data) { |
| for (Vertex* v = outerMesh.fHead; v; v = v->fNext) { |
| for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { |
| Vertex* v0 = e->fTop; |
| Vertex* v1 = e->fBottom; |
| Vertex* v2 = e->fBottom->fPartner; |
| Vertex* v3 = e->fTop->fPartner; |
| data = emit_triangle(v0, v1, v2, aaParams, data); |
| data = emit_triangle(v0, v2, v3, aaParams, data); |
| } |
| } |
| return data; |
| } |
| |
| } // namespace |
| |
| namespace GrTessellator { |
| |
| // Stage 6: Triangulate the monotone polygons into a vertex buffer. |
| |
| int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, |
| VertexAllocator* vertexAllocator, bool antialias, const GrColor& color, |
| bool canTweakAlphaForCoverage, bool* isLinear) { |
| int contourCnt = get_contour_count(path, tolerance); |
| if (contourCnt <= 0) { |
| *isLinear = true; |
| return 0; |
| } |
| SkArenaAlloc alloc(kArenaChunkSize); |
| VertexList outerMesh; |
| Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, antialias, |
| isLinear, &outerMesh); |
| SkPath::FillType fillType = antialias ? SkPath::kWinding_FillType : path.getFillType(); |
| int count = count_points(polys, fillType); |
| if (antialias) { |
| count += count_outer_mesh_points(outerMesh); |
| } |
| if (0 == count) { |
| return 0; |
| } |
| |
| void* verts = vertexAllocator->lock(count); |
| if (!verts) { |
| SkDebugf("Could not allocate vertices\n"); |
| return 0; |
| } |
| |
| LOG("emitting %d verts\n", count); |
| AAParams aaParams; |
| aaParams.fTweakAlpha = canTweakAlphaForCoverage; |
| aaParams.fColor = color; |
| |
| void* end = polys_to_triangles(polys, fillType, antialias ? &aaParams : nullptr, verts); |
| end = outer_mesh_to_triangles(outerMesh, &aaParams, end); |
| int actualCount = static_cast<int>((static_cast<uint8_t*>(end) - static_cast<uint8_t*>(verts)) |
| / vertexAllocator->stride()); |
| SkASSERT(actualCount <= count); |
| vertexAllocator->unlock(actualCount); |
| return actualCount; |
| } |
| |
| int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, |
| GrTessellator::WindingVertex** verts) { |
| int contourCnt = get_contour_count(path, tolerance); |
| if (contourCnt <= 0) { |
| return 0; |
| } |
| SkArenaAlloc alloc(kArenaChunkSize); |
| bool isLinear; |
| Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, false, &isLinear, |
| nullptr); |
| SkPath::FillType fillType = path.getFillType(); |
| int count = count_points(polys, fillType); |
| if (0 == count) { |
| *verts = nullptr; |
| return 0; |
| } |
| |
| *verts = new GrTessellator::WindingVertex[count]; |
| GrTessellator::WindingVertex* vertsEnd = *verts; |
| SkPoint* points = new SkPoint[count]; |
| SkPoint* pointsEnd = points; |
| for (Poly* poly = polys; poly; poly = poly->fNext) { |
| if (apply_fill_type(fillType, poly)) { |
| SkPoint* start = pointsEnd; |
| pointsEnd = static_cast<SkPoint*>(poly->emit(nullptr, pointsEnd)); |
| while (start != pointsEnd) { |
| vertsEnd->fPos = *start; |
| vertsEnd->fWinding = poly->fWinding; |
| ++start; |
| ++vertsEnd; |
| } |
| } |
| } |
| int actualCount = static_cast<int>(vertsEnd - *verts); |
| SkASSERT(actualCount <= count); |
| SkASSERT(pointsEnd - points == actualCount); |
| delete[] points; |
| return actualCount; |
| } |
| |
| } // namespace |