/*
* 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 "GrBatchFlushState.h"
#include "GrBatchTest.h"
#include "GrDefaultGeoProcFactory.h"
#include "GrPathUtils.h"
#include "GrVertices.h"
#include "GrResourceCache.h"
#include "GrResourceProvider.h"
#include "SkGeometry.h"
#include "SkChunkAlloc.h"
#include "batches/GrVertexBatch.h"
#include <stdio.h>
/*
* There are six stages to the 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()).
*
* 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, which 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 three 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 splitting the neighbour edge on the
* intersected vertex (cleanup_active_edges()).
* C) Shortening an edge may cause an active edge to become inactive or an inactive edge
* to become active. This is handled by removing or inserting the edge in the active
* edge list (fix_active_state()).
*
* 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
#define ALLOC_NEW(Type, args, alloc) new (alloc.allocThrow(sizeof(Type))) Type args
namespace {
struct Vertex;
struct Edge;
struct Poly;
template <class T, T* T::*Prev, T* T::*Next>
void 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 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)
: fPoint(point), fPrev(nullptr), fNext(nullptr)
, fFirstEdgeAbove(nullptr), fLastEdgeAbove(nullptr)
, fFirstEdgeBelow(nullptr), fLastEdgeBelow(nullptr)
, fProcessed(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; // "
bool fProcessed; // Has this vertex been seen in simplify()?
#if LOGGING_ENABLED
float fID; // Identifier used for logging.
#endif
};
/***************************************************************************************/
typedef bool (*CompareFunc)(const SkPoint& a, const SkPoint& b);
struct Comparator {
CompareFunc sweep_lt;
CompareFunc sweep_gt;
};
bool sweep_lt_horiz(const SkPoint& a, const SkPoint& b) {
return a.fX == b.fX ? a.fY > b.fY : a.fX < b.fX;
}
bool sweep_lt_vert(const SkPoint& a, const SkPoint& b) {
return a.fY == b.fY ? a.fX < b.fX : a.fY < b.fY;
}
bool sweep_gt_horiz(const SkPoint& a, const SkPoint& b) {
return a.fX == b.fX ? a.fY < b.fY : a.fX > b.fX;
}
bool sweep_gt_vert(const SkPoint& a, const SkPoint& b) {
return a.fY == b.fY ? a.fX > b.fX : a.fY > b.fY;
}
inline SkPoint* emit_vertex(Vertex* v, SkPoint* data) {
*data++ = v->fPoint;
return data;
}
SkPoint* emit_triangle(Vertex* v0, Vertex* v1, Vertex* v2, SkPoint* data) {
#if WIREFRAME
data = emit_vertex(v0, data);
data = emit_vertex(v1, data);
data = emit_vertex(v1, data);
data = emit_vertex(v2, data);
data = emit_vertex(v2, data);
data = emit_vertex(v0, data);
#else
data = emit_vertex(v0, data);
data = emit_vertex(v1, data);
data = emit_vertex(v2, data);
#endif
return data;
}
struct EdgeList {
EdgeList() : fHead(nullptr), fTail(nullptr) {}
Edge* fHead;
Edge* fTail;
};
/**
* 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 which require it (e.g.,
* cleanup_active_edges()). 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 {
Edge(Vertex* top, Vertex* bottom, int winding)
: fWinding(winding)
, fTop(top)
, fBottom(bottom)
, fLeft(nullptr)
, fRight(nullptr)
, fPrevEdgeAbove(nullptr)
, fNextEdgeAbove(nullptr)
, fPrevEdgeBelow(nullptr)
, fNextEdgeBelow(nullptr)
, fLeftPoly(nullptr)
, fRightPoly(nullptr) {
recompute();
}
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.
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.
double fDX; // The line equation for this edge, in implicit form.
double fDY; // fDY * x + fDX * y + fC = 0, for point (x, y) on the line.
double fC;
double dist(const SkPoint& p) const {
return fDY * p.fX - fDX * p.fY + fC;
}
bool isRightOf(Vertex* v) const {
return dist(v->fPoint) < 0.0;
}
bool isLeftOf(Vertex* v) const {
return dist(v->fPoint) > 0.0;
}
void recompute() {
fDX = static_cast<double>(fBottom->fPoint.fX) - fTop->fPoint.fX;
fDY = static_cast<double>(fBottom->fPoint.fY) - fTop->fPoint.fY;
fC = static_cast<double>(fTop->fPoint.fY) * fBottom->fPoint.fX -
static_cast<double>(fTop->fPoint.fX) * fBottom->fPoint.fY;
}
bool intersect(const Edge& other, SkPoint* p) {
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 = fDX * other.fDY - fDY * other.fDX;
if (denom == 0.0) {
return false;
}
double dx = static_cast<double>(fTop->fPoint.fX) - other.fTop->fPoint.fX;
double dy = static_cast<double>(fTop->fPoint.fY) - other.fTop->fPoint.fY;
double sNumer = dy * other.fDX - dx * other.fDY;
double tNumer = dy * fDX - dx * fDY;
// 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 * fDX);
p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fDY);
return true;
}
bool isActive(EdgeList* activeEdges) const {
return activeEdges && (fLeft || fRight || activeEdges->fHead == this);
}
};
/***************************************************************************************/
struct Poly {
Poly(int winding)
: fWinding(winding)
, fHead(nullptr)
, fTail(nullptr)
, fActive(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 { kNeither_Side, kLeft_Side, kRight_Side } Side;
struct MonotonePoly {
MonotonePoly()
: fSide(kNeither_Side)
, fHead(nullptr)
, fTail(nullptr)
, fPrev(nullptr)
, fNext(nullptr) {}
Side fSide;
Vertex* fHead;
Vertex* fTail;
MonotonePoly* fPrev;
MonotonePoly* fNext;
bool addVertex(Vertex* v, Side side, SkChunkAlloc& alloc) {
Vertex* newV = ALLOC_NEW(Vertex, (v->fPoint), alloc);
bool done = false;
if (fSide == kNeither_Side) {
fSide = side;
} else {
done = side != fSide;
}
if (fHead == nullptr) {
fHead = fTail = newV;
} else if (fSide == kRight_Side) {
newV->fPrev = fTail;
fTail->fNext = newV;
fTail = newV;
} else {
newV->fNext = fHead;
fHead->fPrev = newV;
fHead = newV;
}
return done;
}
SkPoint* emit(SkPoint* data) {
Vertex* first = fHead;
Vertex* v = first->fNext;
while (v != fTail) {
SkASSERT(v && v->fPrev && v->fNext);
Vertex* prev = v->fPrev;
Vertex* curr = v;
Vertex* next = v->fNext;
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, data);
v->fPrev->fNext = v->fNext;
v->fNext->fPrev = v->fPrev;
if (v->fPrev == first) {
v = v->fNext;
} else {
v = v->fPrev;
}
} else {
v = v->fNext;
}
}
return data;
}
};
Poly* addVertex(Vertex* v, Side side, SkChunkAlloc& alloc) {
LOG("addVertex() to %d at %g (%g, %g), %s side\n", fID, v->fID, v->fPoint.fX, v->fPoint.fY,
side == kLeft_Side ? "left" : side == kRight_Side ? "right" : "neither");
Poly* partner = fPartner;
Poly* poly = this;
if (partner) {
fPartner = partner->fPartner = nullptr;
}
if (!fActive) {
fActive = ALLOC_NEW(MonotonePoly, (), alloc);
}
if (fActive->addVertex(v, side, alloc)) {
if (fTail) {
fActive->fPrev = fTail;
fTail->fNext = fActive;
fTail = fActive;
} else {
fHead = fTail = fActive;
}
if (partner) {
partner->addVertex(v, side, alloc);
poly = partner;
} else {
Vertex* prev = fActive->fSide == Poly::kLeft_Side ?
fActive->fHead->fNext : fActive->fTail->fPrev;
fActive = ALLOC_NEW(MonotonePoly, , alloc);
fActive->addVertex(prev, Poly::kNeither_Side, alloc);
fActive->addVertex(v, side, alloc);
}
}
fCount++;
return poly;
}
void end(Vertex* v, SkChunkAlloc& alloc) {
LOG("end() %d at %g, %g\n", fID, v->fPoint.fX, v->fPoint.fY);
if (fPartner) {
fPartner = fPartner->fPartner = nullptr;
}
addVertex(v, fActive->fSide == kLeft_Side ? kRight_Side : kLeft_Side, alloc);
}
SkPoint* emit(SkPoint *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(data);
}
return data;
}
int fWinding;
MonotonePoly* fHead;
MonotonePoly* fTail;
MonotonePoly* fActive;
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, SkChunkAlloc& alloc) {
Poly* poly = ALLOC_NEW(Poly, (winding), alloc);
poly->addVertex(v, Poly::kNeither_Side, alloc);
poly->fNext = *head;
*head = poly;
return poly;
}
Vertex* append_point_to_contour(const SkPoint& p, Vertex* prev, Vertex** head,
SkChunkAlloc& alloc) {
Vertex* v = ALLOC_NEW(Vertex, (p), alloc);
#if LOGGING_ENABLED
static float gID = 0.0f;
v->fID = gID++;
#endif
if (prev) {
prev->fNext = v;
v->fPrev = prev;
} else {
*head = v;
}
return v;
}
Vertex* generate_quadratic_points(const SkPoint& p0,
const SkPoint& p1,
const SkPoint& p2,
SkScalar tolSqd,
Vertex* prev,
Vertex** head,
int pointsLeft,
SkChunkAlloc& alloc) {
SkScalar d = p1.distanceToLineSegmentBetweenSqd(p0, p2);
if (pointsLeft < 2 || d < tolSqd || !SkScalarIsFinite(d)) {
return append_point_to_contour(p2, prev, head, alloc);
}
const SkPoint q[] = {
{ SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) },
{ SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) },
};
const SkPoint r = { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) };
pointsLeft >>= 1;
prev = generate_quadratic_points(p0, q[0], r, tolSqd, prev, head, pointsLeft, alloc);
prev = generate_quadratic_points(r, q[1], p2, tolSqd, prev, head, pointsLeft, alloc);
return prev;
}
Vertex* generate_cubic_points(const SkPoint& p0,
const SkPoint& p1,
const SkPoint& p2,
const SkPoint& p3,
SkScalar tolSqd,
Vertex* prev,
Vertex** head,
int pointsLeft,
SkChunkAlloc& alloc) {
SkScalar d1 = p1.distanceToLineSegmentBetweenSqd(p0, p3);
SkScalar d2 = p2.distanceToLineSegmentBetweenSqd(p0, p3);
if (pointsLeft < 2 || (d1 < tolSqd && d2 < tolSqd) ||
!SkScalarIsFinite(d1) || !SkScalarIsFinite(d2)) {
return append_point_to_contour(p3, prev, head, alloc);
}
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;
prev = generate_cubic_points(p0, q[0], r[0], s, tolSqd, prev, head, pointsLeft, alloc);
prev = generate_cubic_points(s, r[1], q[2], p3, tolSqd, prev, head, pointsLeft, alloc);
return prev;
}
// 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,
Vertex** contours, SkChunkAlloc& alloc, bool *isLinear) {
SkScalar toleranceSqd = tolerance * tolerance;
SkPoint pts[4];
bool done = false;
*isLinear = true;
SkPath::Iter iter(path, false);
Vertex* prev = nullptr;
Vertex* head = nullptr;
if (path.isInverseFillType()) {
SkPoint quad[4];
clipBounds.toQuad(quad);
for (int i = 3; i >= 0; i--) {
prev = append_point_to_contour(quad[i], prev, &head, alloc);
}
head->fPrev = prev;
prev->fNext = head;
*contours++ = head;
head = prev = nullptr;
}
SkAutoConicToQuads converter;
while (!done) {
SkPath::Verb verb = iter.next(pts);
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) {
int pointsLeft = GrPathUtils::quadraticPointCount(quadPts, tolerance);
prev = generate_quadratic_points(quadPts[0], quadPts[1], quadPts[2],
toleranceSqd, prev, &head, pointsLeft, alloc);
quadPts += 2;
}
*isLinear = false;
break;
}
case SkPath::kMove_Verb:
if (head) {
head->fPrev = prev;
prev->fNext = head;
*contours++ = head;
}
head = prev = nullptr;
prev = append_point_to_contour(pts[0], prev, &head, alloc);
break;
case SkPath::kLine_Verb: {
prev = append_point_to_contour(pts[1], prev, &head, alloc);
break;
}
case SkPath::kQuad_Verb: {
int pointsLeft = GrPathUtils::quadraticPointCount(pts, tolerance);
prev = generate_quadratic_points(pts[0], pts[1], pts[2], toleranceSqd, prev,
&head, pointsLeft, alloc);
*isLinear = false;
break;
}
case SkPath::kCubic_Verb: {
int pointsLeft = GrPathUtils::cubicPointCount(pts, tolerance);
prev = generate_cubic_points(pts[0], pts[1], pts[2], pts[3],
toleranceSqd, prev, &head, pointsLeft, alloc);
*isLinear = false;
break;
}
case SkPath::kClose_Verb:
if (head) {
head->fPrev = prev;
prev->fNext = head;
*contours++ = head;
}
head = prev = nullptr;
break;
case SkPath::kDone_Verb:
if (head) {
head->fPrev = prev;
prev->fNext = head;
*contours++ = head;
}
done = true;
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;
}
}
Edge* new_edge(Vertex* prev, Vertex* next, SkChunkAlloc& alloc, Comparator& c) {
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_NEW(Edge, (top, bottom, winding), alloc);
}
void remove_edge(Edge* edge, EdgeList* edges) {
LOG("removing edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID);
SkASSERT(edge->isActive(edges));
remove<Edge, &Edge::fLeft, &Edge::fRight>(edge, &edges->fHead, &edges->fTail);
}
void insert_edge(Edge* edge, Edge* prev, EdgeList* edges) {
LOG("inserting edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID);
SkASSERT(!edge->isActive(edges));
Edge* next = prev ? prev->fRight : edges->fHead;
insert<Edge, &Edge::fLeft, &Edge::fRight>(edge, prev, next, &edges->fHead, &edges->fTail);
}
void find_enclosing_edges(Vertex* v, EdgeList* edges, Edge** left, Edge** right) {
if (v->fFirstEdgeAbove) {
*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;
return;
}
void find_enclosing_edges(Edge* edge, EdgeList* edges, Comparator& c, Edge** left, Edge** right) {
Edge* prev = nullptr;
Edge* next;
for (next = edges->fHead; next != nullptr; next = next->fRight) {
if ((c.sweep_gt(edge->fTop->fPoint, next->fTop->fPoint) && next->isRightOf(edge->fTop)) ||
(c.sweep_gt(next->fTop->fPoint, edge->fTop->fPoint) && edge->isLeftOf(next->fTop)) ||
(c.sweep_lt(edge->fBottom->fPoint, next->fBottom->fPoint) &&
next->isRightOf(edge->fBottom)) ||
(c.sweep_lt(next->fBottom->fPoint, edge->fBottom->fPoint) &&
edge->isLeftOf(next->fBottom))) {
break;
}
prev = next;
}
*left = prev;
*right = next;
return;
}
void fix_active_state(Edge* edge, EdgeList* activeEdges, Comparator& c) {
if (edge->isActive(activeEdges)) {
if (edge->fBottom->fProcessed || !edge->fTop->fProcessed) {
remove_edge(edge, activeEdges);
}
} else if (edge->fTop->fProcessed && !edge->fBottom->fProcessed) {
Edge* left;
Edge* right;
find_enclosing_edges(edge, activeEdges, c, &left, &right);
insert_edge(edge, left, activeEdges);
}
}
void insert_edge_above(Edge* edge, Vertex* v, Comparator& c) {
if (edge->fTop->fPoint == edge->fBottom->fPoint ||
c.sweep_gt(edge->fTop->fPoint, edge->fBottom->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;
}
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_gt(edge->fTop->fPoint, edge->fBottom->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;
}
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);
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);
remove<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>(
edge, &edge->fTop->fFirstEdgeBelow, &edge->fTop->fLastEdgeBelow);
}
void erase_edge_if_zero_winding(Edge* edge, EdgeList* edges) {
if (edge->fWinding != 0) {
return;
}
LOG("erasing edge (%g -> %g)\n", edge->fTop->fID, edge->fBottom->fID);
remove_edge_above(edge);
remove_edge_below(edge);
if (edge->isActive(edges)) {
remove_edge(edge, edges);
}
}
void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c);
void set_top(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) {
remove_edge_below(edge);
edge->fTop = v;
edge->recompute();
insert_edge_below(edge, v, c);
fix_active_state(edge, activeEdges, c);
merge_collinear_edges(edge, activeEdges, c);
}
void set_bottom(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) {
remove_edge_above(edge);
edge->fBottom = v;
edge->recompute();
insert_edge_above(edge, v, c);
fix_active_state(edge, activeEdges, c);
merge_collinear_edges(edge, activeEdges, c);
}
void merge_edges_above(Edge* edge, Edge* other, EdgeList* activeEdges, 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);
other->fWinding += edge->fWinding;
erase_edge_if_zero_winding(other, activeEdges);
edge->fWinding = 0;
erase_edge_if_zero_winding(edge, activeEdges);
} else if (c.sweep_lt(edge->fTop->fPoint, other->fTop->fPoint)) {
other->fWinding += edge->fWinding;
erase_edge_if_zero_winding(other, activeEdges);
set_bottom(edge, other->fTop, activeEdges, c);
} else {
edge->fWinding += other->fWinding;
erase_edge_if_zero_winding(edge, activeEdges);
set_bottom(other, edge->fTop, activeEdges, c);
}
}
void merge_edges_below(Edge* edge, Edge* other, EdgeList* activeEdges, 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);
other->fWinding += edge->fWinding;
erase_edge_if_zero_winding(other, activeEdges);
edge->fWinding = 0;
erase_edge_if_zero_winding(edge, activeEdges);
} else if (c.sweep_lt(edge->fBottom->fPoint, other->fBottom->fPoint)) {
edge->fWinding += other->fWinding;
erase_edge_if_zero_winding(edge, activeEdges);
set_top(other, edge->fBottom, activeEdges, c);
} else {
other->fWinding += edge->fWinding;
erase_edge_if_zero_winding(other, activeEdges);
set_top(edge, other->fBottom, activeEdges, c);
}
}
void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c) {
if (edge->fPrevEdgeAbove && (edge->fTop == edge->fPrevEdgeAbove->fTop ||
!edge->fPrevEdgeAbove->isLeftOf(edge->fTop))) {
merge_edges_above(edge, edge->fPrevEdgeAbove, activeEdges, c);
} else if (edge->fNextEdgeAbove && (edge->fTop == edge->fNextEdgeAbove->fTop ||
!edge->isLeftOf(edge->fNextEdgeAbove->fTop))) {
merge_edges_above(edge, edge->fNextEdgeAbove, activeEdges, c);
}
if (edge->fPrevEdgeBelow && (edge->fBottom == edge->fPrevEdgeBelow->fBottom ||
!edge->fPrevEdgeBelow->isLeftOf(edge->fBottom))) {
merge_edges_below(edge, edge->fPrevEdgeBelow, activeEdges, c);
} else if (edge->fNextEdgeBelow && (edge->fBottom == edge->fNextEdgeBelow->fBottom ||
!edge->isLeftOf(edge->fNextEdgeBelow->fBottom))) {
merge_edges_below(edge, edge->fNextEdgeBelow, activeEdges, c);
}
}
void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc);
void cleanup_active_edges(Edge* edge, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc) {
Vertex* top = edge->fTop;
Vertex* bottom = edge->fBottom;
if (edge->fLeft) {
Vertex* leftTop = edge->fLeft->fTop;
Vertex* leftBottom = edge->fLeft->fBottom;
if (c.sweep_gt(top->fPoint, leftTop->fPoint) && !edge->fLeft->isLeftOf(top)) {
split_edge(edge->fLeft, edge->fTop, activeEdges, c, alloc);
} else if (c.sweep_gt(leftTop->fPoint, top->fPoint) && !edge->isRightOf(leftTop)) {
split_edge(edge, leftTop, activeEdges, c, alloc);
} else if (c.sweep_lt(bottom->fPoint, leftBottom->fPoint) &&
!edge->fLeft->isLeftOf(bottom)) {
split_edge(edge->fLeft, bottom, activeEdges, c, alloc);
} else if (c.sweep_lt(leftBottom->fPoint, bottom->fPoint) && !edge->isRightOf(leftBottom)) {
split_edge(edge, leftBottom, activeEdges, c, alloc);
}
}
if (edge->fRight) {
Vertex* rightTop = edge->fRight->fTop;
Vertex* rightBottom = edge->fRight->fBottom;
if (c.sweep_gt(top->fPoint, rightTop->fPoint) && !edge->fRight->isRightOf(top)) {
split_edge(edge->fRight, top, activeEdges, c, alloc);
} else if (c.sweep_gt(rightTop->fPoint, top->fPoint) && !edge->isLeftOf(rightTop)) {
split_edge(edge, rightTop, activeEdges, c, alloc);
} else if (c.sweep_lt(bottom->fPoint, rightBottom->fPoint) &&
!edge->fRight->isRightOf(bottom)) {
split_edge(edge->fRight, bottom, activeEdges, c, alloc);
} else if (c.sweep_lt(rightBottom->fPoint, bottom->fPoint) &&
!edge->isLeftOf(rightBottom)) {
split_edge(edge, rightBottom, activeEdges, c, alloc);
}
}
}
void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc) {
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);
if (c.sweep_lt(v->fPoint, edge->fTop->fPoint)) {
set_top(edge, v, activeEdges, c);
} else if (c.sweep_gt(v->fPoint, edge->fBottom->fPoint)) {
set_bottom(edge, v, activeEdges, c);
} else {
Edge* newEdge = ALLOC_NEW(Edge, (v, edge->fBottom, edge->fWinding), alloc);
insert_edge_below(newEdge, v, c);
insert_edge_above(newEdge, edge->fBottom, c);
set_bottom(edge, v, activeEdges, c);
cleanup_active_edges(edge, activeEdges, c, alloc);
fix_active_state(newEdge, activeEdges, c);
merge_collinear_edges(newEdge, activeEdges, c);
}
}
void merge_vertices(Vertex* src, Vertex* dst, Vertex** head, Comparator& c, SkChunkAlloc& alloc) {
LOG("found coincident verts at %g, %g; merging %g into %g\n", src->fPoint.fX, src->fPoint.fY,
src->fID, dst->fID);
for (Edge* edge = src->fFirstEdgeAbove; edge;) {
Edge* next = edge->fNextEdgeAbove;
set_bottom(edge, dst, nullptr, c);
edge = next;
}
for (Edge* edge = src->fFirstEdgeBelow; edge;) {
Edge* next = edge->fNextEdgeBelow;
set_top(edge, dst, nullptr, c);
edge = next;
}
remove<Vertex, &Vertex::fPrev, &Vertex::fNext>(src, head, nullptr);
}
Vertex* check_for_intersection(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c,
SkChunkAlloc& alloc) {
SkPoint p;
if (!edge || !other) {
return nullptr;
}
if (edge->intersect(*other, &p)) {
Vertex* v;
LOG("found intersection, pt is %g, %g\n", p.fX, p.fY);
if (p == edge->fTop->fPoint || c.sweep_lt(p, edge->fTop->fPoint)) {
split_edge(other, edge->fTop, activeEdges, c, alloc);
v = edge->fTop;
} else if (p == edge->fBottom->fPoint || c.sweep_gt(p, edge->fBottom->fPoint)) {
split_edge(other, edge->fBottom, activeEdges, c, alloc);
v = edge->fBottom;
} else if (p == other->fTop->fPoint || c.sweep_lt(p, other->fTop->fPoint)) {
split_edge(edge, other->fTop, activeEdges, c, alloc);
v = other->fTop;
} else if (p == other->fBottom->fPoint || c.sweep_gt(p, other->fBottom->fPoint)) {
split_edge(edge, other->fBottom, activeEdges, c, alloc);
v = other->fBottom;
} else {
Vertex* nextV = edge->fTop;
while (c.sweep_lt(p, nextV->fPoint)) {
nextV = nextV->fPrev;
}
while (c.sweep_lt(nextV->fPoint, p)) {
nextV = nextV->fNext;
}
Vertex* prevV = nextV->fPrev;
if (coincident(prevV->fPoint, p)) {
v = prevV;
} else if (coincident(nextV->fPoint, p)) {
v = nextV;
} else {
v = ALLOC_NEW(Vertex, (p), alloc);
LOG("inserting between %g (%g, %g) and %g (%g, %g)\n",
prevV->fID, prevV->fPoint.fX, prevV->fPoint.fY,
nextV->fID, nextV->fPoint.fX, nextV->fPoint.fY);
#if LOGGING_ENABLED
v->fID = (nextV->fID + prevV->fID) * 0.5f;
#endif
v->fPrev = prevV;
v->fNext = nextV;
prevV->fNext = v;
nextV->fPrev = v;
}
split_edge(edge, v, activeEdges, c, alloc);
split_edge(other, v, activeEdges, c, alloc);
}
return v;
}
return nullptr;
}
void sanitize_contours(Vertex** contours, int contourCnt) {
for (int i = 0; i < contourCnt; ++i) {
SkASSERT(contours[i]);
for (Vertex* v = contours[i];;) {
if (coincident(v->fPrev->fPoint, v->fPoint)) {
LOG("vertex %g,%g coincident; removing\n", v->fPoint.fX, v->fPoint.fY);
if (v->fPrev == v) {
contours[i] = nullptr;
break;
}
v->fPrev->fNext = v->fNext;
v->fNext->fPrev = v->fPrev;
if (contours[i] == v) {
contours[i] = v->fNext;
}
v = v->fPrev;
} else {
v = v->fNext;
if (v == contours[i]) break;
}
}
}
}
void merge_coincident_vertices(Vertex** vertices, Comparator& c, SkChunkAlloc& alloc) {
for (Vertex* v = (*vertices)->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, vertices, c, alloc);
}
}
}
// Stage 2: convert the contours to a mesh of edges connecting the vertices.
Vertex* build_edges(Vertex** contours, int contourCnt, Comparator& c, SkChunkAlloc& alloc) {
Vertex* vertices = nullptr;
Vertex* prev = nullptr;
for (int i = 0; i < contourCnt; ++i) {
for (Vertex* v = contours[i]; v != nullptr;) {
Vertex* vNext = v->fNext;
Edge* edge = new_edge(v->fPrev, v, alloc, c);
if (edge->fWinding > 0) {
insert_edge_below(edge, v->fPrev, c);
insert_edge_above(edge, v, c);
} else {
insert_edge_below(edge, v, c);
insert_edge_above(edge, v->fPrev, c);
}
merge_collinear_edges(edge, nullptr, c);
if (prev) {
prev->fNext = v;
v->fPrev = prev;
} else {
vertices = v;
}
prev = v;
v = vNext;
if (v == contours[i]) break;
}
}
if (prev) {
prev->fNext = vertices->fPrev = nullptr;
}
return vertices;
}
// Stage 3: sort the vertices by increasing sweep direction.
Vertex* sorted_merge(Vertex* a, Vertex* b, Comparator& c);
void front_back_split(Vertex* v, Vertex** pFront, Vertex** pBack) {
Vertex* fast;
Vertex* slow;
if (!v || !v->fNext) {
*pFront = v;
*pBack = nullptr;
} else {
slow = v;
fast = v->fNext;
while (fast != nullptr) {
fast = fast->fNext;
if (fast != nullptr) {
slow = slow->fNext;
fast = fast->fNext;
}
}
*pFront = v;
*pBack = slow->fNext;
slow->fNext->fPrev = nullptr;
slow->fNext = nullptr;
}
}
void merge_sort(Vertex** head, Comparator& c) {
if (!*head || !(*head)->fNext) {
return;
}
Vertex* a;
Vertex* b;
front_back_split(*head, &a, &b);
merge_sort(&a, c);
merge_sort(&b, c);
*head = sorted_merge(a, b, c);
}
inline void append_vertex(Vertex* v, Vertex** head, Vertex** tail) {
insert<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, *tail, nullptr, head, tail);
}
inline void append_vertex_list(Vertex* v, Vertex** head, Vertex** tail) {
insert<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, *tail, v->fNext, head, tail);
}
Vertex* sorted_merge(Vertex* a, Vertex* b, Comparator& c) {
Vertex* head = nullptr;
Vertex* tail = nullptr;
while (a && b) {
if (c.sweep_lt(a->fPoint, b->fPoint)) {
Vertex* next = a->fNext;
append_vertex(a, &head, &tail);
a = next;
} else {
Vertex* next = b->fNext;
append_vertex(b, &head, &tail);
b = next;
}
}
if (a) {
append_vertex_list(a, &head, &tail);
}
if (b) {
append_vertex_list(b, &head, &tail);
}
return head;
}
// Stage 4: Simplify the mesh by inserting new vertices at intersecting edges.
void simplify(Vertex* vertices, Comparator& c, SkChunkAlloc& alloc) {
LOG("simplifying complex polygons\n");
EdgeList activeEdges;
for (Vertex* v = vertices; v != nullptr; v = v->fNext) {
if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) {
continue;
}
#if LOGGING_ENABLED
LOG("\nvertex %g: (%g,%g)\n", v->fID, v->fPoint.fX, v->fPoint.fY);
#endif
Edge* leftEnclosingEdge = nullptr;
Edge* rightEnclosingEdge = nullptr;
bool restartChecks;
do {
restartChecks = false;
find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge);
if (v->fFirstEdgeBelow) {
for (Edge* edge = v->fFirstEdgeBelow; edge != nullptr; edge = edge->fNextEdgeBelow) {
if (check_for_intersection(edge, leftEnclosingEdge, &activeEdges, c, alloc)) {
restartChecks = true;
break;
}
if (check_for_intersection(edge, rightEnclosingEdge, &activeEdges, c, alloc)) {
restartChecks = true;
break;
}
}
} else {
if (Vertex* pv = check_for_intersection(leftEnclosingEdge, rightEnclosingEdge,
&activeEdges, c, alloc)) {
if (c.sweep_lt(pv->fPoint, v->fPoint)) {
v = pv;
}
restartChecks = true;
}
}
} while (restartChecks);
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;
}
v->fProcessed = true;
}
}
// Stage 5: Tessellate the simplified mesh into monotone polygons.
Poly* tessellate(Vertex* vertices, SkChunkAlloc& alloc) {
LOG("tessellating simple polygons\n");
EdgeList activeEdges;
Poly* polys = nullptr;
for (Vertex* v = vertices; v != nullptr; v = v->fNext) {
if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) {
continue;
}
#if LOGGING_ENABLED
LOG("\nvertex %g: (%g,%g)\n", v->fID, v->fPoint.fX, v->fPoint.fY);
#endif
Edge* leftEnclosingEdge = nullptr;
Edge* rightEnclosingEdge = nullptr;
find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge);
Poly* leftPoly = nullptr;
Poly* rightPoly = nullptr;
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->addVertex(v, Poly::kRight_Side, alloc);
}
if (rightPoly) {
rightPoly = rightPoly->addVertex(v, Poly::kLeft_Side, alloc);
}
for (Edge* e = v->fFirstEdgeAbove; e != v->fLastEdgeAbove; e = e->fNextEdgeAbove) {
Edge* leftEdge = e;
Edge* rightEdge = e->fNextEdgeAbove;
SkASSERT(rightEdge->isRightOf(leftEdge->fTop));
remove_edge(leftEdge, &activeEdges);
if (leftEdge->fRightPoly) {
leftEdge->fRightPoly->end(v, alloc);
}
if (rightEdge->fLeftPoly && rightEdge->fLeftPoly != leftEdge->fRightPoly) {
rightEdge->fLeftPoly->end(v, 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 && leftPoly == rightPoly) {
// Split the poly.
if (leftPoly->fActive->fSide == Poly::kLeft_Side) {
leftPoly = new_poly(&polys, leftEnclosingEdge->fTop, leftPoly->fWinding,
alloc);
leftPoly->addVertex(v, Poly::kRight_Side, alloc);
rightPoly->addVertex(v, Poly::kLeft_Side, alloc);
leftEnclosingEdge->fRightPoly = leftPoly;
} else {
rightPoly = new_poly(&polys, rightEnclosingEdge->fTop, rightPoly->fWinding,
alloc);
rightPoly->addVertex(v, Poly::kLeft_Side, alloc);
leftPoly->addVertex(v, Poly::kRight_Side, alloc);
rightEnclosingEdge->fLeftPoly = rightPoly;
}
} else {
if (leftPoly) {
leftPoly = leftPoly->addVertex(v, Poly::kRight_Side, alloc);
}
if (rightPoly) {
rightPoly = rightPoly->addVertex(v, 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;
}
// This is a driver function which calls stages 2-5 in turn.
Poly* contours_to_polys(Vertex** contours, int contourCnt, const SkRect& pathBounds,
SkChunkAlloc& alloc) {
Comparator c;
if (pathBounds.width() > pathBounds.height()) {
c.sweep_lt = sweep_lt_horiz;
c.sweep_gt = sweep_gt_horiz;
} else {
c.sweep_lt = sweep_lt_vert;
c.sweep_gt = sweep_gt_vert;
}
#if LOGGING_ENABLED
for (int i = 0; i < contourCnt; ++i) {
Vertex* v = contours[i];
SkASSERT(v);
LOG("path.moveTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY);
for (v = v->fNext; v != contours[i]; v = v->fNext) {
LOG("path.lineTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY);
}
}
#endif
sanitize_contours(contours, contourCnt);
Vertex* vertices = build_edges(contours, contourCnt, c, alloc);
if (!vertices) {
return nullptr;
}
// Sort vertices in Y (secondarily in X).
merge_sort(&vertices, c);
merge_coincident_vertices(&vertices, c, alloc);
#if LOGGING_ENABLED
for (Vertex* v = vertices; v != nullptr; v = v->fNext) {
static float gID = 0.0f;
v->fID = gID++;
}
#endif
simplify(vertices, c, alloc);
return tessellate(vertices, alloc);
}
Poly* path_to_polys(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds,
int contourCnt, SkChunkAlloc& alloc, bool* isLinear) {
SkPath::FillType fillType = path.getFillType();
if (SkPath::IsInverseFillType(fillType)) {
contourCnt++;
}
SkAutoTDeleteArray<Vertex*> contours(new Vertex* [contourCnt]);
path_to_contours(path, tolerance, clipBounds, contours.get(), alloc, isLinear);
return contours_to_polys(contours.get(), contourCnt, path.getBounds(), alloc);
}
void get_contour_count_and_size_estimate(const SkPath& path, SkScalar tolerance, int* contourCnt,
int* sizeEstimate) {
int maxPts = GrPathUtils::worstCasePointCount(path, contourCnt, tolerance);
if (maxPts <= 0) {
*contourCnt = 0;
return;
}
if (maxPts > ((int)SK_MaxU16 + 1)) {
SkDebugf("Path not rendered, too many verts (%d)\n", maxPts);
*contourCnt = 0;
return;
}
// For the initial size of the chunk allocator, estimate based on the point count:
// one vertex per point for the initial passes, plus two for the vertices in the
// resulting Polys, since the same point may end up in two Polys. Assume minimal
// connectivity of one Edge per Vertex (will grow for intersections).
*sizeEstimate = maxPts * (3 * sizeof(Vertex) + sizeof(Edge));
}
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->fWinding) && poly->fCount >= 3) {
count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3);
}
}
return count;
}
} // namespace
namespace GrTessellator {
// Stage 6: Triangulate the monotone polygons into a vertex buffer.
int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds,
GrResourceProvider* resourceProvider,
SkAutoTUnref<GrVertexBuffer>& vertexBuffer, bool canMapVB, bool* isLinear) {
int contourCnt;
int sizeEstimate;
get_contour_count_and_size_estimate(path, tolerance, &contourCnt, &sizeEstimate);
if (contourCnt <= 0) {
*isLinear = true;
return 0;
}
SkChunkAlloc alloc(sizeEstimate);
Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, isLinear);
SkPath::FillType fillType = path.getFillType();
int count = count_points(polys, fillType);
if (0 == count) {
return 0;
}
size_t size = count * sizeof(SkPoint);
if (!vertexBuffer.get() || vertexBuffer->gpuMemorySize() < size) {
vertexBuffer.reset(resourceProvider->createVertexBuffer(
size, GrResourceProvider::kStatic_BufferUsage, 0));
}
if (!vertexBuffer.get()) {
SkDebugf("Could not allocate vertices\n");
return 0;
}
SkPoint* verts;
if (canMapVB) {
verts = static_cast<SkPoint*>(vertexBuffer->map());
} else {
verts = new SkPoint[count];
}
SkPoint* end = verts;
for (Poly* poly = polys; poly; poly = poly->fNext) {
if (apply_fill_type(fillType, poly->fWinding)) {
end = poly->emit(end);
}
}
int actualCount = static_cast<int>(end - verts);
LOG("actual count: %d\n", actualCount);
SkASSERT(actualCount <= count);
if (canMapVB) {
vertexBuffer->unmap();
} else {
vertexBuffer->updateData(verts, actualCount * sizeof(SkPoint));
delete[] verts;
}
return actualCount;
}
int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds,
GrTessellator::WindingVertex** verts) {
int contourCnt;
int sizeEstimate;
get_contour_count_and_size_estimate(path, tolerance, &contourCnt, &sizeEstimate);
if (contourCnt <= 0) {
return 0;
}
SkChunkAlloc alloc(sizeEstimate);
bool isLinear;
Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, &isLinear);
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->fWinding)) {
SkPoint* start = pointsEnd;
pointsEnd = poly->emit(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