/**
* Calculate dx, dy values for a point
*
* @param t : parameter
* @param delta : where to store dx, dy values
*/
private void calcTangentAt(double t, FPoint2 delta) {
final boolean db = false;
if (db) {
System.out.println("calcTangentAt " + t);
}
t = toInt(t);
if (db) {
System.out.println(" flipped=" + flipped() + " ti=" + t);
}
double a = toW2.get(0, 0), b = toW2.get(0, 1), c = toW2.get(0, 2);
double d = toW2.get(1, 0), e = toW2.get(1, 1), f = toW2.get(1, 2);
if (db) {
System.out.println(" a=" + a + " b=" + b + " c=" + c + "\n d=" + d + " e=" + e + " f=" + f);
}
double rt = Polyn.sqrt(A + B * t * t);
double dx = a * B * t / rt + b;
double dy = d * B * t / rt + e;
if (flipped()) {
dx = -dx;
dy = -dy;
}
if (db) {
System.out.println(" dx=" + dx + "\n dy=" + dy);
System.out.println(" ratio=" + (dy / dx));
}
delta.setLocation(dx, dy);
}
/**
* Calculate a point on the hyperbola
*
* @param t : parameter in internal space (after flipping has occurred)
* @param dest : where to store the calculated point
*/
private FPoint2 calcPointInternal(double t, FPoint2 dest) {
final boolean db = false;
if (!valid) throw new FPError("calcPoint of invalid hyperbola");
// Tools.ASSERT(valid, "calcPoint of invalid hyperbola");
// final FPoint2 work = new FPoint2();
//
// work.setLocation(Polyn.sqrt(A + t * t * B), t);
dest = toW2.apply(Polyn.sqrt(A + t * t * B), t, dest);
//
// if (dest == null)
// dest = new FPoint2();
// Matrix.apply(toW2, work, dest);
if (db) {
System.out.println(
"calcPoint t="
+ Tools.f(toExt(t)) // + " armsp=" + work
+ " world="
+ dest);
}
return dest;
}
/**
* Calculate a point on the hyperbola, leave in arm space
*
* @param t : parameter, after conversion to 'internal' value
* @return point in arm space
*/
private FPoint2 calcPointInArmSpace0(double t) {
return new FPoint2(Polyn.sqrt(A + t * t * B), t);
}
/**
* Constructor
*
* @param f1 FPoint2
* @param f2 FPoint2
* @param pt FPoint2, or null for bisector
*/
private void construct(FPoint2 f1, FPoint2 f2, FPoint2 pt) {
// userData[LEFT] = new DArray();
// userData[RIGHT] =new DArray();
final boolean db = false;
if (db) {
System.out.println("Hyperbola constructor\n f1=" + f1 + "\n f2=" + f2 + "\n pt=" + pt);
}
boolean bisector = (pt == null);
initializeVisibleSegments();
// if point on arm is closer to f2 than f1, swap f1 & f2.
if (!bisector && FPoint2.distanceSquared(f1, pt) > FPoint2.distanceSquared(f2, pt)) {
flipped = true;
}
this.foci[RIGHT] = new FPoint2(f1);
this.foci[LEFT] = new FPoint2(f2);
if (!bisector) {
this.pt = new FPoint2(pt);
}
double fociDist = FPoint2.distance(f1, f2);
if (fociDist == 0) {
throw new FPError("Hyperbola foci are same point");
}
c = fociDist * .5;
// calculate the translation of the hyperbola away from
// standard position.
FPoint2 rFocus = getFocus(0), lFocus = getFocus(1);
origin = new FPoint2(.5 * (rFocus.x + lFocus.x), .5 * (rFocus.y + lFocus.y));
// calculate the angle of rotation of the hyperbola away
// from the standard position.
double theta = Math.atan2(rFocus.y - lFocus.y, rFocus.x - lFocus.x);
Matrix fromCenterInW = Matrix.getTranslate(origin, true);
Matrix rotToE = Matrix.getRotate(-theta);
toE2 = rotToE;
Matrix.mult(toE2, fromCenterInW, toE2);
// calculate inverse
toW2 = toE2.invert(null);
// Matrix toCenterInW = Matrix.translationMatrix(origin, false);
// Matrix rotToW = Matrix.getRotate2D(theta);
//
// toW2 = toCenterInW;
// Matrix.mult(toW2, rotToW, toW2);
// Tools.warn("just invert matrix here");
//
if (bisector) {
valid = true;
} else {
// get the arm point in hyperbola space.
FPoint2 workPt = toE2.apply(pt, null);
double xs = workPt.x * workPt.x;
double cs = c * c;
Polyn q = new Polyn(1, -(cs + xs + workPt.y * workPt.y), cs * xs);
if (db) {
System.out.println("a2 quadratic:\n" + q);
}
final DArray qsoln = new DArray();
q.solve(qsoln);
if (db) {
Streams.out.println(qsoln);
}
double val = q.c(1) * -.5;
int ql = qsoln.size();
if (ql >= 1) {
val = qsoln.getDouble(0);
}
// choose the root that is less than c*c.
if (ql == 2) {
if (val > qsoln.getDouble(1)) {
val = qsoln.getDouble(1);
if (db) {
System.out.println(" two roots, choosing smaller.");
}
}
}
if (db) {
System.out.println(" root chosen=" + val);
}
a = Polyn.sqrt(val);
A = a * a;
B = A / (c * c - A);
}
valid = true;
if (db) {
System.out.println(" ==> " + this);
}
}
