Wanted to make an object bounce inside a circle, ended up making the object move along the rim of the circle

Question

Here\'s the code in question:

public void calculate() {
        // Center of circle is at (250, 250).
        //THIS ALGORITHM IS NOW PROVEN TO BE WORSE THAN         


        

Answer 1

Can you do bouncing off a straight wall of arbitrary angle? That should be the first step. (You may find that a polar representation of the velocity vector is easier to work with.)

Once you've got that working, it should be fairly straightforward: bouncing off a circle is like bouncing off a tangent of that circle that touches it at the point of contact.

You can calculate this tangent by observing that it's perpendicular to the radius vector in the point of contact (that is the vector that points from where the object is to the centre of the circle)