c# - 难以理解沿着局部和全局空间的统一运动

Question

CharacterController _charController;

// ...

moveInputX = Input.GetAxis("Horizontal") * speed;
moveInputZ = Input.GetAxis("Vertical") * speed;
Vector3 movement = new Vector3(moveInputX, 0, moveInputZ);
movement = Vector3.ClampMagnitude(movement, speed);

movement.y = -9.81f;

movement *= Time.deltaTime;
movement = transform.TransformDirection(movement);
_charController.Move(movement);

我有一个旋转的玩家，我想让他向本地方向移动，但我不明白何时从其移动的代码中删除 movement = transform.TransformDirection(movement);到全局方向，这没有任何意义，因为这行代码将方向从局部空间转换为全局空间。

Answer 1

这是因为 CharacterController.Move 需要世界空间中的向量。遗憾的是，相关文档从未明确说明这一点。

当您在此处计算运动时:

Vector3 movement = new Vector3(moveInputX, 0, moveInputZ);

您可以看到它没有考虑角色变换的旋转。为了做到这一点，您需要找到该向量在世界空间中被解释为在角色的本地空间中时的样子。这正是这一行的作用:

movement = transform.TransformDirection(movement);

它将运动从本地空间转换为世界空间。

2018.1 CharacterController.Move documentation实际上在其示例中使用了 transform.TransformDirection:

using UnityEngine;
using System.Collections;

// The GameObject is made to bounce using the space key.
// Also the GameOject can be moved forward/backward and left/right.
// Add a Quad to the scene so this GameObject can collider with a floor.

public class ExampleScript : MonoBehaviour
{
    public float speed = 6.0f;
    public float jumpSpeed = 8.0f;
    public float gravity = 20.0f;

    private Vector3 moveDirection = Vector3.zero;
    private CharacterController controller;

    void Start()
    {
        controller = GetComponent<CharacterController>();

        // let the gameObject fall down
        gameObject.transform.position = new Vector3(0, 5, 0);
    }

    void Update()
    {
        if (controller.isGrounded)
        {
            // We are grounded, so recalculate
            // move direction directly from axes

            moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0.0f, Input.GetAxis("Vertical"));
            moveDirection = transform.TransformDirection(moveDirection);
            moveDirection = moveDirection * speed;

            if (Input.GetButton("Jump"))
            {
                moveDirection.y = jumpSpeed;
            }
        }

        // Apply gravity
        moveDirection.y = moveDirection.y - (gravity * Time.deltaTime);

        // Move the controller
        controller.Move(moveDirection * Time.deltaTime);
    }
}