From 5045de33e75455e6e149548f3e35bdec87d01086 Mon Sep 17 00:00:00 2001 From: Chris Dalton Date: Thu, 7 Jan 2021 19:09:01 -0700 Subject: [PATCH] Move GrTriangulator nested struct defs into the .h file This makes them reusable for the AA triangulator when it gets its own file. Bug: skia:10419 Change-Id: Ibf77b9a77aabc57898c0526b3a6c02ab9c46e2cc Reviewed-on: https://skia-review.googlesource.com/c/skia/+/351876 Commit-Queue: Chris Dalton Reviewed-by: Jim Van Verth --- src/gpu/GrTriangulator.cpp | 614 +++++++++++-------------------------- src/gpu/GrTriangulator.h | 249 +++++++++++++++ 2 files changed, 429 insertions(+), 434 deletions(-) diff --git a/src/gpu/GrTriangulator.cpp b/src/gpu/GrTriangulator.cpp index 913dd9f944..d0ed4d3692 100644 --- a/src/gpu/GrTriangulator.cpp +++ b/src/gpu/GrTriangulator.cpp @@ -21,9 +21,7 @@ #include -#define LOGGING_ENABLED 0 - -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING #define TESS_LOG printf #else #define TESS_LOG(...) @@ -74,49 +72,6 @@ static void list_remove(T* t, T** head, T** tail) { 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 GrTriangulator::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) - , fSynthetic(false) -#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; - bool fSynthetic; // Is this a synthetic vertex? -#if LOGGING_ENABLED - float fID; // Identifier used for logging. -#endif -}; - -/***************************************************************************************/ - typedef bool (*CompareFunc)(const SkPoint& a, const SkPoint& b); static bool sweep_lt_horiz(const SkPoint& a, const SkPoint& b) { @@ -127,14 +82,9 @@ static bool sweep_lt_vert(const SkPoint& a, const SkPoint& b) { return a.fY < b.fY || (a.fY == b.fY && a.fX < b.fX); } -struct GrTriangulator::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; -}; +bool GrTriangulator::Comparator::sweep_lt(const SkPoint& a, const SkPoint& b) const { + return fDirection == Direction::kHorizontal ? sweep_lt_horiz(a, b) : sweep_lt_vert(a, b); +} static inline void* emit_vertex(Vertex* v, bool emitCoverage, void* data) { GrVertexWriter verts{data}; @@ -166,42 +116,13 @@ static void* emit_triangle(Vertex* v0, Vertex* v1, Vertex* v2, bool emitCoverage return data; } -struct GrTriangulator::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(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(v, &fHead, &fTail); - } - void close() { - if (fHead && fTail) { - fTail->fNext = fHead; - fHead->fPrev = fTail; - } - } -}; +void GrTriangulator::VertexList::insert(Vertex* v, Vertex* prev, Vertex* next) { + list_insert(v, prev, next, &fHead, &fTail); +} + +void GrTriangulator::VertexList::remove(Vertex* v) { + list_remove(v, &fHead, &fTail); +} // Round to nearest quarter-pixel. This is used for screenspace tessellation. @@ -214,163 +135,56 @@ static inline SkScalar double_to_clamped_scalar(double d) { return SkDoubleToScalar(std::min((double) SK_ScalarMax, std::max(d, (double) -SK_ScalarMax))); } -// A line equation in implicit form. fA * x + fB * y + fC = 0, for all points (x, y) on the line. -struct GrTriangulator::Line { - Line(double a, double b, double c) : fA(a), fB(b), fC(c) {} - Line(Vertex* p, Vertex* q) : Line(p->fPoint, q->fPoint) {} - Line(const SkPoint& p, const SkPoint& q) - : fA(static_cast(q.fY) - p.fY) // a = dY - , fB(static_cast(p.fX) - q.fX) // b = -dX - , fC(static_cast(p.fY) * q.fX - // c = cross(q, p) - static_cast(p.fX) * q.fY) {} - double dist(const SkPoint& p) const { - return fA * p.fX + fB * p.fY + fC; - } - Line operator*(double v) const { - return Line(fA * v, fB * v, fC * v); - } - double magSq() const { - return fA * fA + fB * fB; - } - void normalize() { - double len = sqrt(this->magSq()); - if (len == 0.0) { - return; - } - double scale = 1.0f / len; - fA *= scale; - fB *= scale; - fC *= scale; - } - bool nearParallel(const Line& o) const { - return fabs(o.fA - fA) < 0.00001 && fabs(o.fB - fB) < 0.00001; +bool GrTriangulator::Line::intersect(const Line& other, SkPoint* point) const { + double denom = fA * other.fB - fB * other.fA; + if (denom == 0.0) { + return false; } + double scale = 1.0 / denom; + point->fX = double_to_clamped_scalar((fB * other.fC - other.fB * fC) * scale); + point->fY = double_to_clamped_scalar((other.fA * fC - fA * other.fC) * scale); + round(point); + return point->isFinite(); +} - // Compute the intersection of two (infinite) Lines. - bool intersect(const Line& other, SkPoint* point) const { - double denom = fA * other.fB - fB * other.fA; - if (denom == 0.0) { - return false; - } - double scale = 1.0 / denom; - point->fX = double_to_clamped_scalar((fB * other.fC - other.fB * fC) * scale); - point->fY = double_to_clamped_scalar((other.fA * fC - fA * other.fC) * scale); - round(point); - return point->isFinite(); +bool GrTriangulator::Edge::intersect(const Edge& other, SkPoint* p, uint8_t* alpha) const { + TESS_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 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 GrTriangulator::Edge { - Edge(Vertex* top, Vertex* bottom, int winding, EdgeType 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. - EdgeType 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); + double denom = fLine.fA * other.fLine.fB - fLine.fB * other.fLine.fA; + if (denom == 0.0) { + return false; } - bool isRightOf(Vertex* v) const { - return fLine.dist(v->fPoint) < 0.0; + double dx = static_cast(other.fTop->fPoint.fX) - fTop->fPoint.fX; + double dy = static_cast(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; } - bool isLeftOf(Vertex* v) const { - return fLine.dist(v->fPoint) > 0.0; + 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 == EdgeType::kConnector) { + *alpha = (1.0 - s) * fTop->fAlpha + s * fBottom->fAlpha; + } else if (other.fType == EdgeType::kConnector) { + double t = tNumer / denom; + *alpha = (1.0 - t) * other.fTop->fAlpha + t * other.fBottom->fAlpha; + } else if (fType == EdgeType::kOuter && other.fType == EdgeType::kOuter) { + *alpha = 0; + } else { + *alpha = 255; + } } - void recompute() { - fLine = Line(fTop, fBottom); - } - bool intersect(const Edge& other, SkPoint* p, uint8_t* alpha = nullptr) const { - TESS_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(other.fTop->fPoint.fX) - fTop->fPoint.fX; - double dy = static_cast(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 == EdgeType::kConnector) { - *alpha = (1.0 - s) * fTop->fAlpha + s * fBottom->fAlpha; - } else if (other.fType == EdgeType::kConnector) { - double t = tNumer / denom; - *alpha = (1.0 - t) * other.fTop->fAlpha + t * other.fBottom->fAlpha; - } else if (fType == EdgeType::kOuter && other.fType == EdgeType::kOuter) { - *alpha = 0; - } else { - *alpha = 255; - } - } - return true; - } -}; + return true; +} struct SSEdge; @@ -394,34 +208,12 @@ struct SSEdge { typedef std::unordered_map SSVertexMap; typedef std::vector SSEdgeList; -struct GrTriangulator::EdgeList { - EdgeList() : fHead(nullptr), fTail(nullptr) {} - Edge* fHead; - Edge* fTail; - void insert(Edge* edge, Edge* prev, Edge* next) { - list_insert(edge, prev, next, &fHead, &fTail); - } - void append(Edge* e) { - insert(e, fTail, nullptr); - } - void remove(Edge* edge) { - list_remove(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; - } -}; +void GrTriangulator::EdgeList::insert(Edge* edge, Edge* prev, Edge* next) { + list_insert(edge, prev, next, &fHead, &fTail); +} +void GrTriangulator::EdgeList::remove(Edge* edge) { + list_remove(edge, &fHead, &fTail); +} struct EventList; @@ -497,173 +289,127 @@ static void create_event(SSEdge* edge, Vertex* v, SSEdge* other, Vertex* dest, E } } -struct GrTriangulator::MonotonePoly { - MonotonePoly(Edge* edge, Side side, int winding) - : fSide(side) - , fFirstEdge(nullptr) - , fLastEdge(nullptr) - , fPrev(nullptr) - , fNext(nullptr) - , fWinding(winding) { - this->addEdge(edge); - } - Side fSide; - Edge* fFirstEdge; - Edge* fLastEdge; - MonotonePoly* fPrev; - MonotonePoly* fNext; - int fWinding; - void addEdge(Edge* edge) { - if (fSide == kRight_Side) { - SkASSERT(!edge->fUsedInRightPoly); - list_insert( - edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); - edge->fUsedInRightPoly = true; - } else { - SkASSERT(!edge->fUsedInLeftPoly); - list_insert( - edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); - edge->fUsedInLeftPoly = true; - } +void GrTriangulator::MonotonePoly::addEdge(Edge* edge) { + if (fSide == kRight_Side) { + SkASSERT(!edge->fUsedInRightPoly); + list_insert( + edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); + edge->fUsedInRightPoly = true; + } else { + SkASSERT(!edge->fUsedInLeftPoly); + list_insert( + edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); + edge->fUsedInLeftPoly = true; } +} - void* emit(bool emitCoverage, 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++; +void* GrTriangulator::MonotonePoly::emit(bool emitCoverage, 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; } - 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 this->emitTriangle(prev, curr, next, emitCoverage, data); - } - double ax = static_cast(curr->fPoint.fX) - prev->fPoint.fX; - double ay = static_cast(curr->fPoint.fY) - prev->fPoint.fY; - double bx = static_cast(next->fPoint.fX) - curr->fPoint.fX; - double by = static_cast(next->fPoint.fY) - curr->fPoint.fY; - if (ax * by - ay * bx >= 0.0) { - data = this->emitTriangle(prev, curr, next, emitCoverage, data); - v->fPrev->fNext = v->fNext; - v->fNext->fPrev = v->fPrev; - count--; - if (v->fPrev == first) { - v = v->fNext; - } else { - v = v->fPrev; - } - } else { + 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 this->emitTriangle(prev, curr, next, emitCoverage, data); + } + double ax = static_cast(curr->fPoint.fX) - prev->fPoint.fX; + double ay = static_cast(curr->fPoint.fY) - prev->fPoint.fY; + double bx = static_cast(next->fPoint.fX) - curr->fPoint.fX; + double by = static_cast(next->fPoint.fY) - curr->fPoint.fY; + if (ax * by - ay * bx >= 0.0) { + data = this->emitTriangle(prev, curr, next, emitCoverage, data); + v->fPrev->fNext = v->fNext; + v->fNext->fPrev = v->fPrev; + count--; + if (v->fPrev == first) { v = v->fNext; - } - } - return data; - } - void* emitTriangle(Vertex* prev, Vertex* curr, Vertex* next, bool emitCoverage, - void* data) const { - if (fWinding < 0) { - // Ensure our triangles always wind in the same direction as if the path had been - // triangulated as a simple fan (a la red book). - std::swap(prev, next); - } - return emit_triangle(next, curr, prev, emitCoverage, data); - } -}; - -struct GrTriangulator::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++; - TESS_LOG("*** created Poly %d\n", fID); -#endif - } - Poly* addEdge(Edge* e, Side side, SkArenaAlloc& alloc) { - TESS_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(e, side, fWinding); - fCount += 2; - } else if (e->fBottom == fTail->fLastEdge->fBottom) { - return poly; - } else if (side == fTail->fSide) { - fTail->addEdge(e); - fCount++; - } else { - e = alloc.make(fTail->fLastEdge->fBottom, e->fBottom, 1, EdgeType::kInner); - fTail->addEdge(e); - fCount++; - if (partner) { - partner->addEdge(e, side, alloc); - poly = partner; } else { - MonotonePoly* m = alloc.make(e, side, fWinding); - m->fPrev = fTail; - fTail->fNext = m; - fTail = m; + v = v->fPrev; } + } else { + v = v->fNext; } - return poly; } - void* emit(bool emitCoverage, void *data) { - if (fCount < 3) { - return data; + return data; +} + +void* GrTriangulator::MonotonePoly::emitTriangle(Vertex* prev, Vertex* curr, Vertex* next, + bool emitCoverage, void* data) const { + if (fWinding < 0) { + // Ensure our triangles always wind in the same direction as if the path had been + // triangulated as a simple fan (a la red book). + std::swap(prev, next); + } + return emit_triangle(next, curr, prev, emitCoverage, data); +} + +Poly* GrTriangulator::Poly::addEdge(Edge* e, Side side, SkArenaAlloc& alloc) { + TESS_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; } - TESS_LOG("emit() %d, size %d\n", fID, fCount); - for (MonotonePoly* m = fHead; m != nullptr; m = m->fNext) { - data = m->emit(emitCoverage, data); + } else { + if (e->fUsedInLeftPoly) { + return this; } + } + if (partner) { + fPartner = partner->fPartner = nullptr; + } + if (!fTail) { + fHead = fTail = alloc.make(e, side, fWinding); + fCount += 2; + } else if (e->fBottom == fTail->fLastEdge->fBottom) { + return poly; + } else if (side == fTail->fSide) { + fTail->addEdge(e); + fCount++; + } else { + e = alloc.make(fTail->fLastEdge->fBottom, e->fBottom, 1, EdgeType::kInner); + fTail->addEdge(e); + fCount++; + if (partner) { + partner->addEdge(e, side, alloc); + poly = partner; + } else { + MonotonePoly* m = alloc.make(e, side, fWinding); + m->fPrev = fTail; + fTail->fNext = m; + fTail = m; + } + } + return poly; +} +void* GrTriangulator::Poly::emit(bool emitCoverage, void *data) { + if (fCount < 3) { 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 -}; - -/***************************************************************************************/ + TESS_LOG("emit() %d, size %d\n", fID, fCount); + for (MonotonePoly* m = fHead; m != nullptr; m = m->fNext) { + data = m->emit(emitCoverage, data); + } + return data; +} static bool coincident(const SkPoint& a, const SkPoint& b) { return a == b; @@ -678,7 +424,7 @@ static Poly* new_poly(Poly** head, Vertex* v, int winding, SkArenaAlloc& alloc) void GrTriangulator::appendPointToContour(const SkPoint& p, VertexList* contour) { Vertex* v = fAlloc.make(p, 255); -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING static float gID = 0.0f; v->fID = gID++; #endif @@ -1212,7 +958,7 @@ static Vertex* create_sorted_vertex(const SkPoint& p, uint8_t alpha, VertexList* v = nextV; } else { v = alloc.make(p, alpha); -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING if (!prevV) { v->fID = mesh->fHead->fID - 1.0f; } else if (!nextV) { @@ -1416,7 +1162,7 @@ static void sorted_merge(VertexList* front, VertexList* back, VertexList* result } else { sorted_merge(front, back, result); } -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING float id = 0.0f; for (Vertex* v = result->fHead; v; v = v->fNext) { v->fID = id++; @@ -1455,7 +1201,7 @@ static void merge_sort(VertexList* vertices) { } static void dump_mesh(const VertexList& mesh) { -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING for (Vertex* v = mesh.fHead; v; v = v->fNext) { TESS_LOG("vertex %g (%g, %g) alpha %d", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); if (Vertex* p = v->fPartner) { @@ -1475,7 +1221,7 @@ static void dump_mesh(const VertexList& mesh) { } static void dump_skel(const SSEdgeList& ssEdges) { -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING for (SSEdge* edge : ssEdges) { if (edge->fEdge) { TESS_LOG("skel edge %g -> %g", @@ -1608,7 +1354,7 @@ Poly* GrTriangulator::tessellate(const VertexList& vertices) { if (!connected(v)) { continue; } -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING TESS_LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); #endif Edge* leftEnclosingEdge; @@ -1623,7 +1369,7 @@ Poly* GrTriangulator::tessellate(const VertexList& vertices) { leftPoly = leftEnclosingEdge ? leftEnclosingEdge->fRightPoly : nullptr; rightPoly = rightEnclosingEdge ? rightEnclosingEdge->fLeftPoly : nullptr; } -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING TESS_LOG("edges above:\n"); for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { TESS_LOG("%g -> %g, lpoly %d, rpoly %d\n", @@ -1704,7 +1450,7 @@ Poly* GrTriangulator::tessellate(const VertexList& vertices) { } v->fLastEdgeBelow->fRightPoly = rightPoly; } -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING TESS_LOG("\nactive edges:\n"); for (Edge* e = activeEdges.fHead; e != nullptr; e = e->fRight) { TESS_LOG("%g -> %g, lpoly %d, rpoly %d\n", @@ -2191,7 +1937,7 @@ static void extract_boundaries(const VertexList& inMesh, VertexList* innerVertic void GrTriangulator::contoursToMesh(VertexList* contours, int contourCnt, VertexList* mesh, const Comparator& c) { -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING for (int i = 0; i < contourCnt; ++i) { Vertex* v = contours[i].fHead; SkASSERT(v); @@ -2216,7 +1962,7 @@ void GrTriangulator::SortMesh(VertexList* vertices, const Comparator& c) { } else { merge_sort(vertices); } -#if LOGGING_ENABLED +#if TRIANGULATOR_LOGGING for (Vertex* v = vertices->fHead; v != nullptr; v = v->fNext) { static float gID = 0.0f; v->fID = gID++; diff --git a/src/gpu/GrTriangulator.h b/src/gpu/GrTriangulator.h index efdc6840a5..6227b352b2 100644 --- a/src/gpu/GrTriangulator.h +++ b/src/gpu/GrTriangulator.h @@ -17,6 +17,7 @@ class GrEagerVertexAllocator; struct SkRect; +#define TRIANGULATOR_LOGGING 0 #define TRIANGULATOR_WIREFRAME 0 /** @@ -200,4 +201,252 @@ private: bool fSimpleInnerPolygons = false; }; +/** + * 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 GrTriangulator::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) + , fSynthetic(false) +#if TRIANGULATOR_LOGGING + , 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; + bool fSynthetic; // Is this a synthetic vertex? +#if TRIANGULATOR_LOGGING + float fID; // Identifier used for logging. +#endif +}; + +struct GrTriangulator::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); + 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); + void close() { + if (fHead && fTail) { + fTail->fNext = fHead; + fHead->fPrev = fTail; + } + } +}; + +// A line equation in implicit form. fA * x + fB * y + fC = 0, for all points (x, y) on the line. +struct GrTriangulator::Line { + Line(double a, double b, double c) : fA(a), fB(b), fC(c) {} + Line(Vertex* p, Vertex* q) : Line(p->fPoint, q->fPoint) {} + Line(const SkPoint& p, const SkPoint& q) + : fA(static_cast(q.fY) - p.fY) // a = dY + , fB(static_cast(p.fX) - q.fX) // b = -dX + , fC(static_cast(p.fY) * q.fX - // c = cross(q, p) + static_cast(p.fX) * q.fY) {} + double dist(const SkPoint& p) const { return fA * p.fX + fB * p.fY + fC; } + Line operator*(double v) const { return Line(fA * v, fB * v, fC * v); } + double magSq() const { return fA * fA + fB * fB; } + void normalize() { + double len = sqrt(this->magSq()); + if (len == 0.0) { + return; + } + double scale = 1.0f / len; + fA *= scale; + fB *= scale; + fC *= scale; + } + bool nearParallel(const Line& o) const { + return fabs(o.fA - fA) < 0.00001 && fabs(o.fB - fB) < 0.00001; + } + + // Compute the intersection of two (infinite) Lines. + bool intersect(const Line& other, SkPoint* point) const; + 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 catastrophic + * 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 GrTriangulator::Edge { + Edge(Vertex* top, Vertex* bottom, int winding, EdgeType 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. + EdgeType 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) const; +}; + +struct GrTriangulator::EdgeList { + EdgeList() : fHead(nullptr), fTail(nullptr) {} + Edge* fHead; + Edge* fTail; + void insert(Edge* edge, Edge* prev, Edge* next); + void append(Edge* e) { insert(e, fTail, nullptr); } + void remove(Edge* edge); + 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 GrTriangulator::MonotonePoly { + MonotonePoly(Edge* edge, Side side, int winding) + : fSide(side) + , fFirstEdge(nullptr) + , fLastEdge(nullptr) + , fPrev(nullptr) + , fNext(nullptr) + , fWinding(winding) { + this->addEdge(edge); + } + Side fSide; + Edge* fFirstEdge; + Edge* fLastEdge; + MonotonePoly* fPrev; + MonotonePoly* fNext; + int fWinding; + void addEdge(Edge*); + void* emit(bool emitCoverage, void* data); + void* emitTriangle(Vertex* prev, Vertex* curr, Vertex* next, bool emitCoverage, + void* data) const; +}; + +struct GrTriangulator::Poly { + Poly(Vertex* v, int winding) + : fFirstVertex(v) + , fWinding(winding) + , fHead(nullptr) + , fTail(nullptr) + , fNext(nullptr) + , fPartner(nullptr) + , fCount(0) + { +#if TRIANGULATOR_LOGGING + static int gID = 0; + fID = gID++; + TESS_LOG("*** created Poly %d\n", fID); +#endif + } + Poly* addEdge(Edge* e, Side side, SkArenaAlloc& alloc); + void* emit(bool emitCoverage, void *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 TRIANGULATOR_LOGGING + int fID; +#endif +}; + +struct GrTriangulator::Comparator { + enum class Direction { kVertical, kHorizontal }; + Comparator(Direction direction) : fDirection(direction) {} + bool sweep_lt(const SkPoint& a, const SkPoint& b) const; + Direction fDirection; +}; + #endif