Unity坐标系

坐标系

World Space

Local Space

Screen Space

Viewport Space

坐标转换

Local Space --> World Space

注意三者的区别

World Space --> Local Space

World Space <–> Screen Space

World Space <–> Viewport Space

练习：判断物体的屏幕坐标

1.如果超过屏幕左侧或右侧，停止运动
2.上进下出，下进上出。
注意：此处使用屏幕坐标限制条件判断是由于Game面板的屏幕宽高比有多种形式，而若使用世界坐标，每次修改屏幕宽高比，限制条件都需要改变。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

/// <summary>
///
/// </summary>
public class PlayerController : MonoBehaviour 
{
    public float moveSpeed = 10;
    private Camera mainCamera;
    private void Start()
    {
        mainCamera =  Camera.main;
    }
    private void Update()
    {
        float hor = Input.GetAxis("Horizontal");
        float ver = Input.GetAxis("Vertical");
        if (hor != 0 || ver != 0)
            Movement(hor, ver);


    }

    private void Movement(float hor, float ver)
    {
        hor *= moveSpeed * Time.deltaTime;
        ver *= moveSpeed * Time.deltaTime;
        //世界坐标转换为屏幕坐标
        Vector3 ScreenPoint = Camera.main.WorldToScreenPoint(this.transform.position);
        //（1）如果超过屏幕左侧或右侧，停止运动
        //如果到了最左边，并且还想向左移动或者到了最右边，还想向右移动。
        if (ScreenPoint.x <= 0 && hor < 0|| ScreenPoint.x >= Screen.width && hor > 0)
        {
            hor = 0;
        }
        //（2）下进上出，上进下出
        if (ScreenPoint.y < 0)
            ScreenPoint.y = Screen.height;
        if (ScreenPoint.y > Screen.height)
            ScreenPoint.y = 0;
        //屏幕坐标转为世界坐标
        this.transform.position = mainCamera.ScreenToWorldPoint(ScreenPoint);

        transform.Translate(hor, 0, ver);
    }
}