GameObject' 不包含 'AddForce' 的定义 || Unity3D

Question

I have an error:

'GameObject' does not contain a definition for 'AddForce' and no accessible extension method
'AddForce' accepting a first argument of type 'GameObject' could be found (are you missing a using directive or an assembly reference?)

Code:

public float power = 500.0f;
GameObject var;

void OnCollisionEnter(Collision myCollision) {
if (myCollision.gameObject.name == "Cube") {
    var = GameObject.Find("Cube");
    var.AddForce(new Vector3(0.0f, 0.0f, power));
  }
}

I want change coords of current object, in a collision with other objects.

Answer 1

From what you are trying to, I am assuming that you are trying to add a force to the object that it has collided with.

First of all, you did:

if (myCollision.gameObject.name == "Cube")
  {
    var = GameObject.Find("Cube");
    var.AddForce(new Vector3(0.0f, 0.0f, power));
  }

Try to avoid GameObject.Find(string) method, as it is an expensive call.
In fact, you don't even need to do that, since you actually have the game object you are colliding with already, that is what the myCollision for.

You can do this instead:

if (myCollision.gameObject.name == "Cube")
  {
    var = myCollision.gameObject; // Aka the gameobject you have collided with.
    var.AddForce(new Vector3(0.0f, 0.0f, power));
  }

Going back to the question , what you were trying to do is to add force to a rigidbody, but however var is of type GameObject , not RigidBody .

What you need to do is to get the component of the RigidBody from the GameObject , like so:

var.GetComponent<Rigidbody>().AddForce(...

Note that a null reference exception occurs if the GameObject does not have a Rigidbody component attached to it.
Make sure the cube you are colliding with has a RigidBody component in the Unity's Inspector.

Also, you might want to note that repeated GetComponent() calls can be expensive. You can consider caching it if possible.