public void applyForce() {
// force is proportional to the diff between restLen and current idst
// a vector from A --> B
Vector diff = new Vector(endA.pos, endB.pos);
// compute the current distance
float dist = diff.getMagnitude();
// compute dx, which is what the force depends on
float dx = Math.abs(dist - restLen);
// a vector containing just the direction component of A --> B
Vector dir = diff.copy().normalize();
Vector force = dir.copy().scale(-K * dx, -K * dx);
if (restLen < getDistance()) {
// forces go INWARDS
endB.addForce(force);
endA.addForce(force.reverse());
} else {
// forces go OUTWARDS
endA.addForce(force);
endB.addForce(force.reverse());
}
}
public void updatePosition(float dt) {
if (fixed) {
netForce.reset(); // Shouldn't accumulate forces if fixed
return;
}
updateAcceleration(dt);
updateVelocity(dt);
Point prev = new Point(pos.x, pos.y);
pos.add(vel.copy().scale(dt, dt));
ensureInBounds();
}
// f = m * a --> a = f / m
private void updateAcceleration(float dt) {
// println("node = " + id + ", netforce = " + netForce);
Vector prev = acc;
Float f1 = new Float(netForce.x);
Float f2 = new Float(netForce.y);
if (f1.isNaN(f1) || f2.isNaN(f2)) {
netForce = new Vector();
}
float scale = 1.0f / mass;
this.acc = netForce.copy().scale(scale, scale);
if (id.equals("*.1.0-10")) {
// println("NewAcc = " + acc);
// System.exit(1);
}
// reset netForce for next time
netForce.reset();
}
private void updateVelocity(float dt) {
Vector prev = vel.copy();
vel.add(acc.scale(dt, dt));
}