/* Do two rects intersect ?
* For each edge in r1, does the edge intersect with any edge in r2 ?
* FIXME: Should add first check for non-intersection of
* bounding boxes of rects (?)
*/
int intersect(LRect r1, LRect r2)
{
int result = 0;
if (edgesIntersect(r1.x1, r1.x2, r1.y1, r1.y2, r2) ||
edgesIntersect(r1.x2, r1.x3, r1.y2, r1.y3, r2) ||
edgesIntersect(r1.x3, r1.x4, r1.y3, r1.y4, r2) ||
edgesIntersect(r1.x4, r1.x1, r1.y4, r1.y1, r2))
result = 1;
return result;
}
int polyOverlap(Point p, Poly * pp, Point q, Poly * qp)
{
Point op, cp;
Point oq, cq;
/* translate bounding boxes */
addpt(&op, p, pp->origin);
addpt(&cp, p, pp->corner);
addpt(&oq, q, qp->origin);
addpt(&cq, q, qp->corner);
/* If bounding boxes don't overlap, done */
if (!pintersect(op, cp, oq, cq))
return 0;
if (ISBOX(pp) && ISBOX(qp))
return 1;
if (ISCIRCLE(pp) && ISCIRCLE(qp)) {
double d =
(pp->corner.x - pp->origin.x + qp->corner.x - qp->origin.x);
double dx = p.x - q.x;
double dy = p.y - q.y;
if ((dx * dx + dy * dy) > (d * d) / 4.0)
return 0;
else
return 1;
}
if (tp1 == NULL) {
tp1 = N_GNEW(maxcnt, Point);
tp2 = N_GNEW(maxcnt, Point);
}
transCopy(pp->verts, pp->nverts, p, tp1);
transCopy(qp->verts, qp->nverts, q, tp2);
return (edgesIntersect(tp1, tp2, pp->nverts, qp->nverts) ||
(inBox(*tp1, oq, cq) && inPoly(tp2, qp->nverts, *tp1)) ||
(inBox(*tp2, op, cp) && inPoly(tp1, pp->nverts, *tp2)));
}
