/**
* Find intersections of hyperbolic arm with a line.
*
* @param s0 : first point on line
* @param s1 : second point on line
* @param ipts : intersection points returned here
*/
public DArray findLineIntersect(FPoint2 s0, FPoint2 s1, DArray ipts) {
if (ipts == null) ipts = new DArray();
ipts.clear();
// transform both line points to curve space
FPoint2 c0 = toCurveSpace(s0, null), c1 = toCurveSpace(s1, null);
double a = c0.x, b = c0.y, c = c1.x, d = c1.y;
double e = d - b;
double f = c - a;
double D = f * f - B * e * e;
double E = 2 * a * f - 2 * b * B * e;
double F = a * a - A - B * b * b;
Polyn q = new Polyn(D, E, F);
DArray roots = new DArray();
q.solve(roots);
for (int i = 0; i < roots.size(); i++) {
double k = roots.getDouble(i);
FPoint2 pt =
// ipts.add(
new FPoint2(s0.x + (s1.x - s0.x) * k, s0.y + (s1.y - s0.y) * k);
// );
// Make sure this point is actually on the arm.
FPoint2 cpt = toCurveSpace(pt, null);
if (cpt.x < 0) {
continue;
}
ipts.add(pt);
}
return ipts;
}
/**
* 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));
}
}
/**
* Find intersections between two hyperbolas
*
* @param a Hyperbola
* @param b Hyperbola
* @param iPts where to store intersection points; null to construct
*/
public static DArray findIntersections(Hyperbola a, Hyperbola b, DArray iPts) {
final boolean db = false;
if (iPts == null) iPts = new DArray();
iPts.clear();
final DArray jPts = new DArray();
// a.initClipIfNec();
// b.initClipIfNec();
if (db) {
System.out.println(
"finding intersections between:\n" + a.toString(true) + "\n" + b.toString(true));
}
PlaneCurve.findIntersect(a.getCurve(), b.getCurve(), jPts);
// filter out false intersections
if (db) {
System.out.println("prefilter # intersections= " + jPts.size());
}
FPoint2 ptc = new FPoint2();
for (int i = 0; i < jPts.size(); i++) {
FPoint2 pt = jPts.getFPoint2(i);
// make sure calculated intersect point is actually on both arms
{
FPoint2 data = a.calcParameterAndDistance(pt);
if (data.y > .001) continue;
data = b.calcParameterAndDistance(pt);
if (data.y > .001) continue;
}
if (!a.isLine()) {
// put in curve space to verify it's to the right of the y axis
a.toCurveSpace(pt, ptc);
if (db) {
System.out.println("Filter " + i + " in curveA= " + ptc);
}
if (ptc.x <= 0) {
if (db) {
System.out.println(" < 0");
}
continue;
}
}
if (!b.isLine()) {
b.toCurveSpace(pt, ptc);
if (db) {
System.out.println(" in curveB= " + ptc);
}
if (ptc.x <= 0) {
if (db) {
System.out.println(" < 0");
}
continue;
}
}
if (db) {
System.out.println(" adding " + pt);
}
iPts.add(pt);
}
return iPts;
}