// Algorithm by broofa @ stackoverflow.com
    // Returns position of where the projectile should head towards to hit the target
    // Returns null if the projectile can never hit the target
    public static Vector2f intercept(Vector2f point, float speed, Vector2f target, Vector2f targetVel) {
        Vector2f difference = new Vector2f(target.x - point.x, target.y - point.y);

        float a = targetVel.x * targetVel.x + targetVel.y * targetVel.y - speed * speed;
        float b = 2 * (targetVel.x * difference.x + targetVel.y * difference.y);
        float c = difference.x * difference.x + difference.y * difference.y;

        Vector2f solutionSet = quad(a, b, c);

        Vector2f intercept = null;
        if (solutionSet != null) {
            float bestFit = Math.min(solutionSet.x, solutionSet.y);
            if (bestFit < 0) {
                bestFit = Math.max(solutionSet.x, solutionSet.y);
            }
            if (bestFit > 0) {
                intercept = new Vector2f(target.x + targetVel.x * bestFit, target.y + targetVel.y * bestFit);
            }
        }

        return intercept;
    }

    public static Vector2f quad(float a, float b, float c) {
        Vector2f solution = null;
        if (Float.compare(Math.abs(a), 0) == 0) {
            if (Float.compare(Math.abs(b), 0) == 0) {
                solution = (Float.compare(Math.abs(c), 0) == 0) ? new Vector2f(0, 0) : null;
            } else {
                solution = new Vector2f(-c / b, -c / b);
            }
        } else {
            float d = b * b - 4 * a * c;
            if (d >= 0) {
                d = (float) Math.sqrt(d);
                a = 2 * a;
                solution = new Vector2f((-b - d) / a, (-b + d) / a);
            }
        }
        return solution;
    }