使用RigidBody.AddRelativeForce改变方向时的奇怪行为 [英] Strange behavior when changing direction using RigidBody.AddRelativeForce

问题描述

(暂时)我的角色是一个立方体.多维数据集使用C#脚本和刚体组件进行映射.

My character is (temporally) a cube. The cube is mapped with a C# script and Rigid Body component.

我在Update()中使用以下代码来更改角色(是刚体)的方向:

I use the following code in Update() to change my character (which is a rigid body)'s direction:

void Update () {
  rigidbody.AddRelativeForce(transform.right * speed, ForceMode.Acceleration);
  if (Input.GetKeyDown(KeyCode.LeftArrow)) {
    gameObject.transform.Rotate(0, -90, 0);
    rigidbody.velocity = transform.right* rigidbody.velocity.magnitude;
  }
  if (Input.GetKeyDown(KeyCode.RightArrow)) {
    gameObject.transform.Rotate(0, 90, 0);
    rigidbody.velocity = transform.right* rigidbody.velocity.magnitude;
  }
}

该行为变为: http://youtu.be/NYPNgAulc-k

我希望角色可以左右旋转90度，并开始在新方向上准确加速.但是现在，它在转弯之后会加速弯曲.有关更多信息，请参见上面的视频.

I expect the character turns 90 degree left / right and start accelerating exactly in its new direction. But now, after it turns, it accelerates in curve. See the above video for more information.

我想念什么?

更新(1月30日)::将transform.right更改为transform.forward，并删除了速度变化线:

UPDATE (30 Jan): Changed transform.right to transform.forward and remove velocity changing lines:

void Update () {
  rigidbody.AddRelativeForce(transform.forward * speed, ForceMode.Acceleration);
  if (Input.GetKeyDown(KeyCode.LeftArrow)) {
    gameObject.transform.Rotate(0, -90, 0);
  }
  if (Input.GetKeyDown(KeyCode.RightArrow)) {
    gameObject.transform.Rotate(0, 90, 0);
  }
}

导致向另一个方向移动(因此我更改了相机指向向量)&当向左或向右箭头时，方向不变；只有Runner对象旋转.

which results in moving in another direction (thus I change the camera pointing vector) & not changing direction when Left or Right arrow; only the Runner object rotates.

演示视频: http://youtu.be/UVG6l14oyjw

更新(2月4日):在下面应用了@Roboto的答案，并进行了一些修改:

UPDATE (4 Feb): Applied @Roboto's answer below, with some modifications made:

void Update () {
     if (Input.GetKeyDown(KeyCode.LeftArrow)) {
       transform.Rotate(0, -90, 0);
       rigidbody.velocity = Vector3.zero;
       rigidbody.angularVelocity = Vector3.zero;
     }
     if (Input.GetKeyDown(KeyCode.RightArrow)) {
       transform.Rotate(0, 90, 0);
       rigidbody.velocity = Vector3.zero;
       rigidbody.angularVelocity = Vector3.zero;
     }
}

void FixedUpdate() {
    // Physics stuff should be done inside FixedUpdate :)
    rigidbody.AddForce(transform.forward * speed, ForceMode.Acceleration);
}

转弯终于可以了.我有一个额外的功能，可以使角色跳跃.在Update()中，我添加了:

Turning is finally okay. I have an extra function that makes the character jump. In Update(), I added:

if ((Input.GetButtonDown("Jump") || isTouched) && isOnGround) {
    isOnGround = false; 
    rigidbody.AddForce(jumpHeight, ForceMode.VelocityChange);
}

其中isOnGround是一个布尔值，当Runner对象接触地面时将其设置为true.但是，在离开地面之前，它会沿Z轴移动.当设备离开地面时，它会滑动到X-Z轴.已更新问题的这一部分是单独询问的:此处.

where isOnGround is a boolean, which sets to true when the Runner object touches the ground. However, before it leaves the ground, it moves along Z axis. When the unit leaves the ground, it slides to X-Z axis. This part of updated question is asked separately: here.

注意:假设Runner对象的质量为3.

Note: Given that the Runner object has mass of 3.

推荐答案

来自文档，Transform.forward:

The blue axis of the transform in world space.

世界空间，所以我们要使用AddForce而不是AddRelativeForce，因为AddRelativeForce将使用局部坐标系来添加力.

World space, so we want to use AddForce instead of AddRelativeForce, since AddRelativeForce would use the local coordinate system to add the force.

这可行:

void Update () {
     if (Input.GetKeyDown(KeyCode.LeftArrow)) {
       transform.Rotate(0, -90, 0);
     }
     if (Input.GetKeyDown(KeyCode.RightArrow)) {
       transform.Rotate(0, 90, 0);
     }
}

void FixedUpdate() {
    // Physics stuff should be done inside FixedUpdate :)
    rigidbody.AddForce(transform.forward * speed, ForceMode.Acceleration);
}

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