// 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 srcPos, float speed, Vector2f dstPos, Vector2f dstVel) {
        Vector2f t = new Vector2f(dstPos.x - srcPos.x, dstPos.y - srcPos.y);
        Vector2f tv = new Vector2f(dstVel);

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

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

        Vector2f sol = null;
        if (ts != null) {
            float ti = Math.min(ts.x, ts.y);
            if (ti < 0) {
                ti = Math.max(ts.x, ts.y);
            }
            if (ti > 0) {
                sol = new Vector2f(dstPos.x + dstVel.x * ti, dstPos.y + dstVel.y * ti);
            }
        }

        return sol;
    }

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