1.15 获取两个矩形的交集

 // 判断矩形是否重叠
    private bool IsRectOverlap(Rect r1, Rect r2)
    {
        if (r1.x + r1.width > r2.x && r2.x + r2.width > r1.x
            && r1.y + r1.height > r2.y && r2.y + r2.height > r1.y)
            return true;
        else
            return false;
    }

    // 获取矩形的交集
    private Rect ComputeJoinRect(Rect r1, Rect r2)
    {
        if (r1.Equals(r2))
            return r1;
        if (!IsRectOverlap(r1, r2))
        {
            //Debug.Log("IsRectOverlap False." + r1.ToString() + ", " + r2.ToString());
            return r1;
        }
        Rect joinRect = new Rect();
        Vector2 p1, p2;
        // 左下角 和 右上角
        p1.x = r1.x >= r2.x ? r1.x : r2.x;
        p1.y = r1.y >= r2.y ? r1.y : r2.y;

        p2.x = r1.x + r1.width <= r2.x + r2.width ? r1.x + r1.width : r2.x + r2.width;
        p2.y = r1.y + r1.height <= r2.y + r2.height ? r1.y + r1.height : r2.y + r2.height;

        if (p2.x > p1.x && p2.y > p1.y)
        {
            joinRect = new Rect(p1.x, p1.y, p2.x - p1.x, p2.y - p1.y);
        }
        //Debug.Log("JoinRect: " + joinRect.ToString());

        return joinRect;
    }