bool intersect(const Quadratic& q1, const Quadratic& q2, Intersections& i) {
if (implicit_matches(q1, q2)) {
// FIXME: compute T values
// compute the intersections of the ends to find the coincident span
bool useVertical = fabs(q1[0].x - q1[2].x) < fabs(q1[0].y - q1[2].y);
double t;
if ((t = axialIntersect(q1, q2[0], useVertical)) >= 0) {
i.addCoincident(t, 0);
}
if ((t = axialIntersect(q1, q2[2], useVertical)) >= 0) {
i.addCoincident(t, 1);
}
useVertical = fabs(q2[0].x - q2[2].x) < fabs(q2[0].y - q2[2].y);
if ((t = axialIntersect(q2, q1[0], useVertical)) >= 0) {
i.addCoincident(0, t);
}
if ((t = axialIntersect(q2, q1[2], useVertical)) >= 0) {
i.addCoincident(1, t);
}
assert(i.fCoincidentUsed <= 2);
return i.fCoincidentUsed > 0;
}
QuadraticIntersections q(q1, q2, i);
bool result = q.intersect();
// FIXME: partial coincidence detection is currently poor. For now, try
// to fix up the data after the fact. In the future, revisit the error
// term to try to avoid this kind of result in the first place.
if (i.fUsed && i.fCoincidentUsed) {
hackToFixPartialCoincidence(q1, q2, i);
}
return result;
}
