//SAT intersection test. http://www.metanetsoftware.com/technique/tutorialA.html
    //returns true on intersection, and sets the least intersecting axis in overlap
    static final PointF overlap = new PointF(0,0); //Q&D PointF pool for collision detection. Assumes single threading.
    @SuppressWarnings("UnusedReturnValue")
    static boolean getOverlap(final Entity a, final Entity b, final PointF overlap) {
        overlap.x = 0.0f;
        overlap.y = 0.0f;
        final float centerDeltaX = a.centerX() - b.centerX();
        final float halfWidths = (a.width() + b.width()) * 0.5f;
        float dx = Math.abs(centerDeltaX);//cache the abs, we need it twice

        if (dx > halfWidths) return false; //no overlap on x == no collision

        final float centerDeltaY = a.centerY() - b.centerY();
        final float halfHeights = (a.height() + b.height()) * 0.5f;
        float dy = Math.abs(centerDeltaY);

        if (dy > halfHeights) return false; //no overlap on y == no collision

        dx = halfWidths - dx; //overlap on x
        dy = halfHeights - dy; //overlap on y
        if (dy < dx) {
            overlap.y = (centerDeltaY < 0) ? -dy : dy;
        } else if (dy > dx) {
            overlap.x = (centerDeltaX < 0) ? -dx : dx;
        } else {
            overlap.x = (centerDeltaX < 0) ? -dx : dx;
            overlap.y = (centerDeltaY < 0) ? -dy : dy;
        }
        return true;
    }