/** Returns a new CircleArc2D. t0 and t1 are position on circle. */
public CircleArc2D subCurve(double t0, double t1) {
double startAngle, extent;
if (this.direct) {
startAngle = t0;
extent = Angle2D.formatAngle(t1 - t0);
} else {
extent = -Angle2D.formatAngle(t1 - t0);
startAngle = Angle2D.formatAngle(-t0);
}
return new CircleArc2D(this, startAngle, extent);
}
public double position(Point2D point) {
double angle = Angle2D.horizontalAngle(xc, yc, point.x(), point.y());
if (direct) return Angle2D.formatAngle(angle - theta);
else return Angle2D.formatAngle(theta - angle);
}