ConvexHull findConvexHull(PointSet *pointSet) {
int pointCount = pointSet->getSize();
pointSet->sortPointsByAngle();
if (pointCount <= 3) { // The points are already a convex hull
ConvexHull hull;
for (int i = 0; i < pointCount; ++i) {
hull.addPoint(*pointSet->getPoint(i));
}
if (pointCount > 0) {
hull.addPoint(*pointSet->getPoint(0));
}
return hull;
}
std::stack<const Point *> candiates;
const Point *prev;
const Point *now;
candiates.push(pointSet->getLastPoint());
candiates.push(pointSet->getReferencePoint()); // Is always the first (idx 0)
// element in the point set
for (int i = 1; i < pointCount;) {
const Point *point = pointSet->getPoint(i);
now = candiates.top();
candiates.pop();
prev = candiates.top();
candiates.push(now);
if (isCCW(prev->pos(), now->pos(), point->pos())) {
if (point->pos() == now->pos() && USE_CUSTOM_ALGO_FIX) {
std::cout << "I saved your algorithm" << std::endl;
} else {
candiates.push(point);
}
++i;
} else {
candiates.pop();
}
}
ConvexHull hull(candiates);
return hull;
}
static size_t computeEdgesAndIntersect(const GrMatrix& matrix,
const GrMatrix& inverse,
GrPoint* vertices,
size_t numVertices,
GrEdgeArray* edges,
float sign) {
if (numVertices < 3) {
return 0;
}
matrix.mapPoints(vertices, numVertices);
if (sign == 0.0f) {
sign = isCCW(vertices, numVertices) ? -1.0f : 1.0f;
}
GrPoint p = sanitizePoint(vertices[numVertices - 1]);
for (size_t i = 0; i < numVertices; ++i) {
GrPoint q = sanitizePoint(vertices[i]);
if (p == q) {
continue;
}
GrDrawState::Edge edge = computeEdge(p, q, sign);
edge.fZ += 0.5f; // Offset by half a pixel along the tangent.
*edges->append() = edge;
p = q;
}
int count = edges->count();
if (count == 0) {
return 0;
}
GrDrawState::Edge prev_edge = edges->at(0);
for (int i = 0; i < count; ++i) {
GrDrawState::Edge edge = edges->at(i < count - 1 ? i + 1 : 0);
if (parallel(edge, prev_edge)) {
// 3 points are collinear; offset by half the tangent instead
vertices[i].fX -= edge.fX * 0.5f;
vertices[i].fY -= edge.fY * 0.5f;
} else {
vertices[i] = prev_edge.intersect(edge);
}
inverse.mapPoints(&vertices[i], 1);
prev_edge = edge;
}
return edges->count();
}
HullState findConvexHullStep(PointSet *pointSet, int simulateUntilStep) {
int step = 0;
int pointCount = pointSet->getSize();
pointSet->sortPointsByAngle();
//++step;
if (step++ == simulateUntilStep) // sort done -> update numbers
{
return HullState::SortDone(step);
}
if (pointCount <= 3) { // The points are already a convex hull
ConvexHull hull;
for (int i = 0; i < pointCount; ++i) {
hull.addPoint(*pointSet->getPoint(i));
}
if (pointCount > 0) {
hull.addPoint(*pointSet->getPoint(0));
}
return HullState::HullFound(hull);
}
std::stack<const Point *> candiates;
const Point *prev;
const Point *now;
candiates.push(pointSet->getLastPoint());
candiates.push(pointSet->getReferencePoint()); // Is always the first (idx 0)
// element in the point set
//++step;
if (step++ == simulateUntilStep) // break print candidates
{
return HullState::CandidateAdded(candiates, step);
}
for (int i = 1; i < pointCount;) {
const Point *point = pointSet->getPoint(i);
now = candiates.top();
candiates.pop();
prev = candiates.top();
candiates.push(now);
if (isCCW(prev->pos(), now->pos(), point->pos())) {
candiates.push(point);
// std::cout << "adding " << i << std::endl;
++i;
//++step;
if (step++ == simulateUntilStep) // break print candidates
{
return HullState::CandidateAdded(candiates, step);
}
} else {
//++step;
if (step++ == simulateUntilStep) // break print candidates
{
return HullState::CandidatePoped(candiates, point, step);
}
// std::cout << "pop" << std::endl;
candiates.pop();
}
}
ConvexHull hull(candiates);
return HullState::HullFound(hull);
}
