如何知道物体是向上移动还是向下移动? [英] How to know if the object is moving upward or downward?

问题描述

我有一个游戏对象，我想确定该对象是向上移动(正向)还是向下移动(负向).我该怎么做?

解决方案

假定对象具有刚体，则可以在附着到GameObject的MonoBehavior的更新方法(或任何与此相关的方法)中使用它.

Rigidbody rb = GetComponent<Rigidbody>();
float verticalVelocity = rb.velocity.y;

如果要沿任何轴移动速度，可以使用点积:

Rigidbody rb = GetComponent<Rigidbody>();
Vector3 someAxisInWorldSpace = transform.forward;
float velocityAlongAxis = Vector3.Dot(rb.velocity, someAxisInWorldSpace); 

上面的代码将为您提供沿GameObject的向前轴的速度(向前速度).

如果对象没有刚体，则可以将其旧位置保存在变量中，然后将其与更新循环中的当前位置进行比较.

Vector3 oldPosition;

private void Start() {
    oldPosition = transform.position;
}

private void Update() {
    Vector3 velocity = transform.position - oldPosition;
    float verticalVelocity = velocity.y / Time.deltaTime; // Divide by dt to get m/s
    oldPosition = transform.position;
}

I have a gameobject and I would like to find out if the object is moving upward (positive) or downward (negative). How do I get to do this?

解决方案

Assuming that the object has a rigidbody, you can use this in the update method (or anywhere for that matter) of a MonoBehavior attached to your GameObject.

Rigidbody rb = GetComponent<Rigidbody>();
float verticalVelocity = rb.velocity.y;

If you want the velocity along any axis, you can use the dot product:

Rigidbody rb = GetComponent<Rigidbody>();
Vector3 someAxisInWorldSpace = transform.forward;
float velocityAlongAxis = Vector3.Dot(rb.velocity, someAxisInWorldSpace); 

The above code would give you the velocity along the GameObject's forward axis (the forward velocity).

If the object doesn't have a rigidbody, you can save its old position in a variable and then compare it to the current position in the update loop.

Vector3 oldPosition;

private void Start() {
    oldPosition = transform.position;
}

private void Update() {
    Vector3 velocity = transform.position - oldPosition;
    float verticalVelocity = velocity.y / Time.deltaTime; // Divide by dt to get m/s
    oldPosition = transform.position;
}

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