Unity3D Physical Rigidbody无法检测到碰撞

Question

I am building a simple game in unity that involves two players that punch each other. Players can move around the stage and click a button to punch in front of them, the goal being to knock the other player off the stage.

I got a punching script from this link , but the way it's written is that the punch doesn't interact with other Rigidbodies during the punch animation, collisions are only detected when the punch function is not active. It was proposed that work with other Rigidbodies that I use Rigidbody.MovePosition() . I tried to implement it with MovePosition() but ended up removing the punch animation and putting me farther away from a solution.

Here is the punch script

IEnumerator Punch(float time, float distance, Vector3 direction)
{
    punching = true;
    var timer = 0.0f;
    var orgPos = transform.position;
    direction.Normalize();
    while (timer <= time) {
        transform.position = orgPos + (Mathf.Sin(timer / time * Mathf.PI) + 1.0f) * direction;
        yield return null;
        timer += Time.deltaTime;
    }
    transform.position = orgPos;
    punching = false;
}

and with MovePosition()

IEnumerator Punch(float time, float distance, Vector3 direction)
{
    punching = true;
    var timer = 0.0f;
    var orgPos = transform.position;
    direction.Normalize();
    rb.MovePosition(orgPos + direction);
    yield return null;
    rb.MovePosition(orgPos);
    punching = false;
}

I am 100% certain that I have the player's physics components set up correctly, the only issue is that there is no collision detection when players punch each other.

Any help is greatly appreciated!

Answer 1

TL;DR : Take the first script and change the transform.position = ...; to rigidbody.MovePosition (...); .

There are two possibilities here: either a) your rigidbody and the target are not configured correctly (for example, one object is a static body), or b) your rigid bodies are never actually intersecting.

Ensuring Physics is Actually Properly Set Up

In case you (or another reader) should need to verify that their physics Rigidbodies are properly configured, check:

1. That the colliding game objects are also NOT marked Static at the top right in the inspector, and
2. That the RigidBody Component is not marked Kinematic.
3. Finally, verify that the GameObject has a properly configured Collider (Box Collider, Sphere Collider, or Capsule Collider, typically).

Determining if Rigid Bodies are Actually Intersecting

The second issue is just dependent on the objects' transform positions within space. Of course, if you're simulating rigidbody objects with physics, you shouldn't be directly specifying these positions, but using the methods of Rigidbody instead, which is why there was the suggestion of using Rigidbody.MovePosition () .

Backing up a little and to make sure any future readers are on the same page, these Punch scripts really have nothing to do with collision detection for rigidbodies, per se, and are really just for changing the position of the GameObject relative to its parent. In other words, the first iteration of the script is just thrusting the fist forward and back over a short time period. The issue here is that it directly modifies the transform, which is ill-advised for non-kinematic Rigidbodies.

The issue with the second script, which attempts to rectify direct assignment of the position using the transform, is that it instantly pushes the hand forward (up to point in the first yield return null ), and then retracts the object on the following frame that the coroutine runs.

Instead, take the first script and change it from using Transform.position = ...; to rigidbody.MovePosition (...); . Doing so should bring back the animated movement of the fist. Also if you haven't already, in void Awake () , you should get a reference to the rigid body, and then store it in a member variable for use here.

Finally, be aware that MovePosition only interpolates movement if the interpolation property is set to true, and by default, interpolation is false except for character controllers. Even so, your second coroutine does not allow enough time for interpolation to occur.

The final script might look something like this:

using UnityEngine;

[RequiresComponent (typeof(Rigidbody))]
public class Puncher : MonoBehaviour {
  Rigidbody _rb;
  bool _isPunching;

  void Awake () {
    _rb = GetComponent<Rigidbody> ()
  }

  void Update () {
    if (!_isPunching && Input.GetKeyDown(KeyCode.Space)) {
      StartCoroutine(Punch(0.5f, 1.25f, transform.forward));
    }
  }

  IEnumerator Punch(float time, float distance, Vector3 direction) {
    _isPunching = true;
    var timer = 0.0f;
    var orgPos = transform.position;
    direction.Normalize();
    while (timer <= time) {
      _rb.MovePosition (orgPos + (Mathf.Sin(timer / time * Mathf.PI) + 1.0f) * direction);
      yield return null;
      timer += Time.deltaTime;
    }
    transform.position = orgPos;
    _isPunching = false;
  }
}