Oval collision detection not working properly

Question

So I\'m trying to implement a test where a oval can connect with a circle, but it\'s not working.

edist = (float) Math.sqrt(
    Math.pow((px + ((pwidth/2) )) -          


        

Answer 1

Finding the intersection is harder than you think. Your col() method is a bit off, but that approach will at best be able to tell you if a single point is within the circle. It won't be able to really detect intersections.

I Googled up some code for computing the actual intersections. I found one in JavaScript that's really interesting and really complicated. Take a look at the source.

If you wanted something a bit simpler (but less accurate), you could check a few points around the ellipse to see if they're within the circle.

private boolean isInCircle(float x, float y) {
    float r = bsize / 2;
    float center_x = bx + r;
    float center_y = by + r;
    float dist = (float) Math.sqrt(Math.pow(x - center_x, 2) + Math.pow(y - center_y, 2));

    return dist < r;
}

public boolean col() {
    return 
        isInCircle(px + pwidth / 2, py              ) || // top
        isInCircle(px + pwidth    , py + pheight / 2) || // right
        isInCircle(px + pwidth / 2, py + pheight    ) || // bottom
        isInCircle(px             , py + pheight / 2);   // left
}