// Do line segments (r1p1.x, r1p1.y)--(r1p2.x, r1p2.y) and (r2p1.x, r2p1.y)--(r2p2.x, r2p2.y) intersect?
// from: http://ptspts.blogspot.com/2010/06/how-to-determine-if-two-line-segments.html
bool doLineSegmentsIntersect(glm::vec2 r1p1, glm::vec2 r1p2, glm::vec2 r2p1, glm::vec2 r2p2) {
int d1 = computeDirection(r2p1.x, r2p1.y, r2p2.x, r2p2.y, r1p1.x, r1p1.y);
int d2 = computeDirection(r2p1.x, r2p1.y, r2p2.x, r2p2.y, r1p2.x, r1p2.y);
int d3 = computeDirection(r1p1.x, r1p1.y, r1p2.x, r1p2.y, r2p1.x, r2p1.y);
int d4 = computeDirection(r1p1.x, r1p1.y, r1p2.x, r1p2.y, r2p2.x, r2p2.y);
return (((d1 > 0 && d2 < 0) || (d1 < 0 && d2 > 0)) &&
((d3 > 0 && d4 < 0) || (d3 < 0 && d4 > 0))) ||
(d1 == 0 && isOnSegment(r2p1.x, r2p1.y, r2p2.x, r2p2.y, r1p1.x, r1p1.y)) ||
(d2 == 0 && isOnSegment(r2p1.x, r2p1.y, r2p2.x, r2p2.y, r1p2.x, r1p2.y)) ||
(d3 == 0 && isOnSegment(r1p1.x, r1p1.y, r1p2.x, r1p2.y, r2p1.x, r2p1.y)) ||
(d4 == 0 && isOnSegment(r1p1.x, r1p1.y, r1p2.x, r1p2.y, r2p2.x, r2p2.y));
}
bool Branch::doLineSegmentsIntersect(QLineF line1, QLineF line2)
{
char d1 = computeDirection(line2.p1().x(), line2.p1().y(), line2.p2().x(), line2.p2().y(), line1.p1().x(), line1.p1().y());
char d2 = computeDirection(line2.p1().x(), line2.p1().y(), line2.p2().x(), line2.p2().y(), line1.p2().x(), line1.p2().y());
char d3 = computeDirection(line1.p1().x(), line1.p1().y(), line1.p2().x(), line1.p2().y(), line2.p1().x(), line2.p1().y());
char d4 = computeDirection(line1.p1().x(), line1.p1().y(), line1.p2().x(), line1.p2().y(), line2.p2().x(), line2.p2().y());
return (((d1 > 0 && d2 < 0) || (d1 < 0 && d2 > 0)) &&
((d3 > 0 && d4 < 0) || (d3 < 0 && d4 > 0))) ||
(d1 == 0 && isOnSegment(line2.p1().x(), line2.p1().y(), line2.p2().x(), line2.p2().y(), line1.p1().x(), line1.p1().y())) ||
(d2 == 0 && isOnSegment(line2.p1().x(), line2.p1().y(), line2.p2().x(), line2.p2().y(), line1.p2().x(), line1.p2().y())) ||
(d3 == 0 && isOnSegment(line1.p1().x(), line1.p1().y(), line1.p2().x(), line1.p2().y(), line2.p1().x(), line2.p1().y())) ||
(d4 == 0 && isOnSegment(line1.p1().x(), line1.p1().y(), line1.p2().x(), line1.p2().y(), line2.p2().x(), line2.p2().y()));
}
/*
* return -1 iff point is outside ring pts
* return 1 iff point is inside ring pts
* return 0 iff point is on ring pts
*/
int point_in_ring_rtree(RTREE_NODE *root, POINT2D *point)
{
int wn = 0;
int i;
double side;
POINT2D seg1;
POINT2D seg2;
LWMLINE *lines;
POSTGIS_DEBUG(2, "point_in_ring called.");
lines = findLineSegments(root, point->y);
if (!lines)
return -1;
for (i=0; i<lines->ngeoms; i++)
{
getPoint2d_p(lines->geoms[i]->points, 0, &seg1);
getPoint2d_p(lines->geoms[i]->points, 1, &seg2);
side = determineSide(&seg1, &seg2, point);
POSTGIS_DEBUGF(3, "segment: (%.8f, %.8f),(%.8f, %.8f)", seg1.x, seg1.y, seg2.x, seg2.y);
POSTGIS_DEBUGF(3, "side result: %.8f", side);
POSTGIS_DEBUGF(3, "counterclockwise wrap %d, clockwise wrap %d", FP_CONTAINS_BOTTOM(seg1.y,point->y,seg2.y), FP_CONTAINS_BOTTOM(seg2.y,point->y,seg1.y));
/* zero length segments are ignored. */
if (((seg2.x-seg1.x)*(seg2.x-seg1.x)+(seg2.y-seg1.y)*(seg2.y-seg1.y)) < 1e-12*1e-12)
{
POSTGIS_DEBUG(3, "segment is zero length... ignoring.");
continue;
}
/* a point on the boundary of a ring is not contained. */
if (fabs(side) < 1e-12)
{
if (isOnSegment(&seg1, &seg2, point) == 1)
{
POSTGIS_DEBUGF(3, "point on ring boundary between points %d, %d", i, i+1);
return 0;
}
}
/*
* If the point is to the left of the line, and it's rising,
* then the line is to the right of the point and
* circling counter-clockwise, so incremement.
*/
if (FP_CONTAINS_BOTTOM(seg1.y,point->y,seg2.y) && side>0)
{
POSTGIS_DEBUG(3, "incrementing winding number.");
++wn;
}
/*
* If the point is to the right of the line, and it's falling,
* then the line is to the right of the point and circling
* clockwise, so decrement.
*/
else if (FP_CONTAINS_BOTTOM(seg2.y,point->y,seg1.y) && side<0)
{
POSTGIS_DEBUG(3, "decrementing winding number.");
--wn;
}
}
POSTGIS_DEBUGF(3, "winding number %d", wn);
if (wn == 0)
return -1;
return 1;
}
