public void calcAcceleration(QTreeNode node, Point p, double scale, double theta, double G) {
double xD;
double yD;
double d;
double f;
if (node.getNW() == null
&& node.getPoint() != null
&& node.getPoint() != p) { // we cant go deeper. calculating for this node
xD = node.getMassCenterX() - p.getX();
yD = node.getMassCenterY() - p.getY();
d = Math.sqrt(xD * xD + yD * yD) / scale;
if (d
< p.getR()
+ node.getPoint()
.getR()) { // if the distance is smaler than (r + p.r) the the force is
// proportional to the distance
d = p.getR() + node.getPoint().getR();
f =
((d / (p.getR() + node.getPoint().getR())) * G * node.getPoint().getM())
/ Math.pow(d, 3);
} else f = (G * node.getM()) / Math.pow(d, 3);
p.setXA(p.getXA() + f * xD);
p.setYA(p.getYA() + f * yD);
} else if (node.getNW() != null) { // we can go deeper so lets chack width to distance ratio
xD = node.getMassCenterX() - p.getX();
yD = node.getMassCenterY() - p.getY();
d = Math.sqrt(xD * xD + yD * yD) / scale;
if (node.getW() / d < theta) { // area is sufficient far away
f = node.getM() / Math.pow(d, 3);
p.setXA(p.getXA() + f * xD);
p.setYA(p.getYA() + f * yD);
} else { // area is to close. Go one level deeper
calcAcceleration(node.getNW(), p, scale, theta, G);
calcAcceleration(node.getNE(), p, scale, theta, G);
calcAcceleration(node.getSW(), p, scale, theta, G);
calcAcceleration(node.getSE(), p, scale, theta, G);
}
}
}
@Override
public void CalculateAcceleration(
ArrayList<Point> pointList,
ArrayList<Point> pointList2,
double minX,
double minY,
double maxX,
double maxY,
double theta,
double G) {
QTree qTree = new QTree(minX, minY, maxX, maxY);
for (Point p2 : pointList2) {
qTree.insertPoint(qTree.getRoot(), p2);
}
for (Point p : pointList) {
p.setXA(0);
p.setYA(0);
this.calcAcceleration(qTree.getRoot(), p, World.scale, theta, G);
}
}