Ceil(10.2f);//向上取整 11
Floor(10.2f);// 向下取整 10
Round(10.2f);// 四舍五入10，0.5时取决于前面的奇偶，偶下
sign(num);//取符号，正数返回1，负数返水-1
clamp(num,0,100);//限制num在0到100
clamp01(num);//限制num在0-1