汽车的速度计一般用于测量车轮的转速。汽车可能不会直接向前移动(例如,可能侧向打滑),在此情况下,部分运动不在速度计可以测量的方向上。对象的 rigidbody.velocity 矢量的大小将给出整体运动方向上的速度,但是为了单独考虑向前的速度,应使用点积:
var fwdSpeed = Vector3.Dot(rigidbody.velocity, transform.forward);
当然,方向可以是您喜欢的任何方向,但为了进行此计算,必须对方向矢量进行归一化。这样,不仅结果比速度大小更准确,而且无需执行在查找大小时需要的缓慢的平方根运算。
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