/**
* Find intersections of hyperbolic arm with an axes-aligned line segment. Arm must intersect
* segment, not its underlying (infinite) line. The intersection points are sorted into increasing
* parameter values w.r.t. the arm.
*
* @param s0 : start of line segment
* @param s1 : end of line segment
* @param ipts : intersection points returned here
* @param reverseOrder : if true, points are sorted by decreasing parameter values
* @param dbFlag : true to print debug information
*/
public void findOrthogonalIntersect(
FPoint2 s0, FPoint2 s1, DArray ipts, boolean reverseOrder, boolean dbFlag) {
final boolean db = true && dbFlag;
if (db) {
System.out.println(
"findOrthogonalIntersect " + s0 + " -> " + s1 + " rev:" + Tools.f(reverseOrder));
}
// Determine whether this is a vertical or horizontal line segment.
boolean vert = (Math.abs(s1.y - s0.y) > Math.abs(s1.x - s0.x));
if (db) {
System.out.println(" vert=" + Tools.f(vert));
}
// Find the quadratic to solve.
Polyn p;
PlaneCurve cv = getCurve();
if (vert) {
p = cv.solveForX(s0.x);
} else {
p = cv.solveForY(s0.y);
}
DArray lst = new DArray();
p.solve(lst);
if (db) {
System.out.println(" curve=" + cv.toString(true));
System.out.println(" polyn=" + p.toString(true));
System.out.println(" roots=" + Tools.d(lst));
}
// Sort points, discarding those not on line segment,
// and those not on the correct arm.
ipts.clear();
for (int i = 0; i < lst.size(); i++) {
double ta = lst.getDouble(i);
FPoint2 pt;
if (vert) {
pt = new FPoint2(s0.x, ta);
} else {
pt = new FPoint2(ta, s0.y);
}
if (db) {
System.out.println(" position on arm for ta=" + ta + " is " + pt);
}
double t = MyMath.positionOnSegment(pt, s0, s1);
if (db) {
System.out.println(" pt=" + pt + " t=" + t);
}
if (t < 0 || t > 1) {
if (db) {
System.out.println(" not on segment, skipping");
}
continue;
}
FPoint2 cpt = toCurveSpace(pt, null);
if (db) {
System.out.println(" curveSpace=" + cpt);
}
if (cpt.x < 0) {
if (db) {
System.out.println(" skipping...");
}
continue;
}
double t1 = calcParameter(pt);
int j = 0;
while (true) {
if (j == ipts.size()) {
break;
}
double t2 = calcParameter(ipts.getFPoint2(j));
if (!reverseOrder) {
if (t1 < t2) {
break;
}
} else if (t1 > t2) {
break;
}
j++;
}
ipts.add(j, pt);
}
if (db) {
System.out.println(" ipts=" + Tools.d(ipts));
}
}
