/**
* Calculates and returns an altitude of the triangle
*
* @return An altitude of the triangle
*/
public Line getAltitude() {
Line base = new Line(pointB, pointC);
double altitudeSlope = base.getPerpSlope();
// D is a point on BC such that AD perp BC
double ax = pointA.getX();
double bx = pointB.getX();
double cx = pointC.getX();
double ay = pointA.getY();
double by = pointB.getY();
double cy = pointC.getY();
// Vertical case:
if (Double.isInfinite(base.getSlope())) return new Line(pointA, new Point(ax, by));
// There has to be an easier way...
// This sorcery brought to you by Wolfram Alpha
double dx =
(ax * bx / (by - cy)
- ax * cx / (by - cy)
- ay * cy / (by - cy)
+ ay * by / (by - cy)
+ cx * (by - cy) / (bx - cx)
- cy)
/ ((by - cy) / (bx - cx) + bx / (by - cy) - cx / (by - cy));
double dy = base.getSlope() * (dx - cx) + cy;
return new Line(pointA, new Point(dx, dy));
}
public static Point getIntersetingPoint(Point start1, Point end1, Point start2, Point end2) {
Point intersection = null;
// Sort Points by occurence on X-Axis
if (start1.getX() > end1.getX()) {
swap(start1, end1);
}
if (start2.getX() > end2.getX()) {
swap(start2, end2);
}
if (start1.getX() > start2.getX()) {
swap(start1, start2);
swap(end1, end2);
}
// Create the Line Segments
Line l1 = new Line(start1, end1);
Line l2 = new Line(start2, end2);
// if slopes are same then it could be parallel lines
if (l1.getSlope() == l2.getSlope()) {
// if the intercepts are same and start2 is in between Start1 and end2, then start 2 is the
// intersecting point
if (l1.getyIntercept() == l2.getyIntercept() && isBetween(start1, start2, end2)) {
return start2;
}
return null;
}
// Else the line slopes are different
double x = (l2.getyIntercept() - l1.getyIntercept()) / (l1.getSlope() - l2.getSlope());
double y = x * l1.getSlope() + l1.getyIntercept();
intersection = new Point(x, y);
if (isBetween(start1, intersection, end1) && isBetween(start2, intersection, end2)) {
return intersection;
}
return null;
}
public boolean parallelTo(Line l2) {
if (this.getSlope() == l2.getSlope()) return true;
else return false;
}
public boolean perpendicularTo(Line l2) {
if (this.getSlope() == (-1 / l2.getSlope())) return true;
else return false;
}
public boolean equals(Line line2) {
if (this.getSlope() == line2.getSlope()
&& this.getC() / this.getB() == line2.getC() / line2.getB()) return true;
else return false;
}