public void drag() {
// If we are draging the ball, we calculate the angle between the
// pendulum origin and mouse location
// we assign that angle to the pendulum
if (dragging) {
Vector3D diff =
Vector3D.sub(origin, new Vector3D(mouseX, mouseY)); // Difference between 2 points
theta = atan2(-1 * diff.y, diff.x) - radians(90); // Angle relative to vertical axis
}
}
// a method that calculates a steering vector towards a target
// takes a second argument, if true, it slows down as it approaches the target
Vector3D steer(Vector3D target, boolean slowdown) {
Vector3D steer; // the steering vector
Vector3D desired =
Vector3D.sub(target, loc); // a vector pointing from the location to the target
float d = desired.magnitude(); // distance from the target is the magnitude of the vector
// if the distance is greater than 0, calc steering (otherwise return zero vector)
if (d > 0) {
// normalize desired
desired.normalize();
// two options for magnitude (1 -- based on distance, 2 -- maxspeed)
if ((slowdown) && (d < 100.0f)) desired.mult(maxspeed * (d / 100.0f));
else desired.mult(maxspeed);
// STEERING VECTOR IS DESIREDVECTOR MINUS VELOCITY
steer = Vector3D.sub(desired, vel);
steer.limit(maxforce); // limit to maximum steering force
} else {
steer = new Vector3D(0, 0);
}
return steer;
}
