Unity3D的几种坐标系

1. World Space（世界坐标）：我们在场景中添加物体（如：Cube），他们都是以世界坐标显示在场景中的。transform.position可以获得该位置坐标。            

2. Screen Space（屏幕坐标，鼠标坐标）:以像素来定义的，以屏幕的左下角为（0，0）点，右上角为（Screen.width，Screen.height），Z的位置是以相机的世界单位来衡量的。注：鼠标位置坐标属于屏幕坐标，Input.mousePosition可以获得该位置坐标，手指触摸屏幕也为屏幕坐标，Input.GetTouch(0).position可以获得单个手指触摸屏幕坐标。

3. ViewPort Space（视口坐标）:视口坐标是标准的和相对于相机的。相机的左下角为（0，0）点，右上角为（1，1）点，Z的位置是以相机的世界单位来衡量的。（用的不多，反正我暂时没有用到~呵呵~）

4. 绘制GUI界面的坐标系：这个坐标系与屏幕坐标系相似，不同的是该坐标系以屏幕的左上角为（0，0）点，右下角为（Screen.width，Screen.height）。

5. LineRender坐标：以屏幕中心为原点，向上向右增加。

• 世界坐标→屏幕坐标：camera.WorldToScreenPoint(transform.position);这样可以将世界坐标转换为屏幕坐标。其中camera为场景中的camera对象。

• 屏幕坐标→视口坐标：camera.ScreenToViewportPoint(Input.GetTouch(0).position);这样可以将屏幕坐标转换为视口坐标。其中camera为场景中的camera对象。

• 视口坐标→屏幕坐标：camera.ViewportToScreenPoint();

• 视口坐标→世界坐标：camera.ViewportToWorldPoint();

案例1——在鼠标点击的位置上绘制一张图片出来（关于绘制GUI界面坐标系与屏幕坐标系之间的关系）。

using UnityEngine;
using System.Collections;

public class ScreenToGUI : MonoBehaviour {

    // Use this for initialization
    void Start () {
    
    }
    
    // Update is called once per frame
    void Update () {
    
    }
  
      //图片  
    public Texture img;    
     //储存鼠标的位置坐标    
    private Vector2 pos;
    void OnGUI()
    {
        //鼠标左击，获取当前鼠标的位置       
        if (Input.GetMouseButton(0))
        {
            pos = Input.mousePosition; //屏幕坐标
        }
        //绘制图片，屏幕坐标和GUI界面坐标只在Y轴上方向相反，只要被Screen.height减就可以互相转换。      
        GUI.DrawTexture(new Rect(pos.x, Screen.height - pos.y, 100, 100), img);
    }

}

案例2——角色头顶的名字（世界坐标转GUI界面坐标）

先世界坐标转屏幕坐标，再屏幕坐标转GUI界面坐标

代码如下：

using UnityEngine;
using System.Collections;

public class Blood : MonoBehaviour {
    public static float ScaleWidht = 0f;
    public static float ScaleHeight = 0f;
    private Rect _drawRect = new Rect();
    public float Width = 0f;
    public float Height = 10f;
    public const float DesignStageWidth = 800;
    public const float DesignStageHeight = 480;

    public Vector2 pos2;
    public float size_z;
    // Use this for initialization
    void Start () {
        ScaleWidht = Screen.width / DesignStageWidth;
        ScaleHeight = Screen.height / DesignStageHeight;
        Height = 2f;

        size_z = transform.gameObject.collider.bounds.size.z;
    }


    // Update is called once per frame
    void Update () {
        //世界坐标转换到屏幕坐标
        print(transform.forward);
        pos2 = Camera.main.WorldToScreenPoint(transform.position + transform.forward * (size_z / 2)); 
        //计算角色头顶坐标
        pos2 = new Vector2(pos2.x, Screen.height  - pos2.y - Height); 



        //Vector3 worldPosition = new Vector3(transform.position.x, transform.position.y + Height, transform.position.z);
        //worldPosition = Camera.mainCamera.WorldToScreenPoint(worldPosition);
        //_drawRect = new Rect((worldPosition.x - 100 * ScaleWidht) / ScaleWidht, (Screen.height - worldPosition.y - 50 * ScaleHeight) / ScaleHeight, 200, 50);
    }

    void OnGUI()
    {
        //GUILayout.BeginArea(_drawRect);
        //    GUILayout.Label("======哈哈======");
        //GUILayout.EndArea();

        GUI.Label(new Rect(pos2.x, pos2.y, 100, 50), "=BETTER=");
    }
}

 案例3——类似屏幕解锁功能的实现（屏幕坐标转换为世界坐标）

首先是创建LineRenderer。GameObject -> Create Empty ->更名为“LineRendererObj”，

给LineRendererObj添加“Line Renderer”组件，Component ->Effects ->Line Renderer;

将它的Positions 的size 设置为0

接下来是代码touch.CS：

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

public class touch : MonoBehaviour {
    private Event e;

    public Texture2D Point;
    public Color c1 = Color.yellow;
    public Color c2 = Color.red;
    public int lengthOfLineRenderer;
    public GameObject LineRendererPrefab;

    private LineRenderer lineRenderer;
    /// <summary>
    /// 保存创建的Line Renderer
    /// </summary>
    private List<LineRenderer> lineRendArray =new List<LineRenderer>();

    private Vector3 screenPoint;
    private Vector3 scanPos;

    private Color[] color;

    /// <summary>
    /// 记录宫格所在GUI位置
    /// </summary>
    public List<Rect> AreaRect = new List<Rect>();
    /// <summary>
    /// 记录宫格中心点
    /// </summary>
    public List<Vector2> CenterPointList = new List<Vector2>();
    /// <summary>
    /// 宫格标签
    /// </summary>
    public int RectFlag;
    /// <summary>
    /// 记录正确的滑动顺序
    /// </summary>
    public List<int> KeyOrder = new List<int>();
    /// <summary>
    /// 记录玩家滑动顺序
    /// </summary>
    public List<int> PlayerKeyOrder = new List<int>();

    /// <summary>
    /// 判断开始鼠标位置是否可画
    /// </summary>
    public bool CheckStartRect=false;

    /// <summary>
    /// 判断结束鼠标位置是否可画
    /// </summary>
    public bool CheckEndRect = false;

    /// <summary>
    /// 行数
    /// </summary>
    public int Row = 4;
    /// <summary>
    /// 列数
    /// </summary>
    public int Column = 4;

    void Start()
    {
        e = Event.current;

        scanPos = LineRendererPrefab.transform.position;
        lineRenderer = (LineRenderer)LineRendererPrefab.GetComponent("LineRenderer");
        lineRenderer.material = new Material(Shader.Find("Particles/Additive"));
        lengthOfLineRenderer = 0;
        lineRenderer.SetColors(c1, c2);
        lineRenderer.SetWidth(0.7F, 0.7F);
        lineRenderer.SetVertexCount(0);

        color = new Color[8];
        color[0] = Color.yellow;
        color[1] = Color.blue;
        color[2] = Color.cyan;
        color[3] = Color.gray;
        color[4] = Color.green;
        color[5] = Color.grey;
        color[6] = Color.magenta;
        color[7] = Color.red;

        for (int RowCount = 0; RowCount < Row; RowCount++)
        {
            for (int columnCount = 0; columnCount < Column; columnCount++)
            {
                Rect IconRect = new Rect(columnCount * Screen.width / Column + Screen.width / Column / 2 - Point.width / 2, RowCount * Screen.height / Row + Screen.height / Row / 2 - Point.height / 2, Point.width, Point.height);
                AreaRect.Add(IconRect);

                Vector2 CenterP = IconRect.center;//得到每个的中心点
                CenterPointList.Add(CenterP);
            }
        }
    }

    void OnGUI()
    {
        e = Event.current;
        for (int RowCount = 0; RowCount < Row; RowCount++)
        {
            for (int columnCount = 0; columnCount < Column; columnCount++)
            {
                Rect IconRect = new Rect(columnCount * Screen.width / Column + Screen.width / Column / 2 - Point.width / 2, RowCount * Screen.height / Row + Screen.height / Row / 2 - Point.height / 2, Point.width, Point.height);
                GUI.Label(IconRect, Point);
            }
        }
    }

    void Update()
    {
        if (e != null)
        {
            if (e.type == EventType.MouseDown)
            {
                for (int i = 0; i < AreaRect.Count; i++)
                {
                    if (AreaRect[i].Contains(new Vector3(Input.mousePosition.x, Screen.height - Input.mousePosition.y, Input.mousePosition.z)))
                    {
                        CheckStartRect = true;
                        print("Contains");
                        PlayerKeyOrder.Add(i);
                        RectFlag = i;
                        break;
                    }
                    else
                    {
                        CheckStartRect = false;
                    }
                }

                if (CheckStartRect)
                {
                    print("MouseDown_____");

                    //Vector3 curPosition = mousePToLineRendererP(); 
                    Vector3 curPosition = centerPToLineRendererP(RectFlag);
                    GameObject newObj;
                    newObj = (GameObject)Instantiate(LineRendererPrefab, LineRendererPrefab.transform.position, LineRendererPrefab.transform.rotation);
                    lineRenderer = (LineRenderer)newObj.GetComponent("LineRenderer");

                    int n = Random.Range(1, 8);
                    c1 = color[n - 1];
                    n = Random.Range(1, 8);
                    c2 = color[n - 1];
                    lineRenderer.SetColors(c1, c2);

                    lineRenderer.SetVertexCount(1);
                    lineRenderer.SetWidth(0.7F, 0.7F);
                    lineRenderer.SetPosition(0, curPosition);
                    lineRendArray.Add(lineRenderer);
                    lengthOfLineRenderer++;
                }
            }

            if (e.type == EventType.MouseDrag&&CheckStartRect)
            {
                print("MouseDrag_____");
                Vector3 curPosition = mousePToLineRendererP(); 
                DrawRenderLine(lineRendArray[lengthOfLineRenderer - 1], curPosition);
            }

            if (e.type == EventType.MouseUp && CheckStartRect)
            {
                for (int i = 0; i < AreaRect.Count; i++)
                {
                    if (AreaRect[i].Contains(new Vector3(Input.mousePosition.x, Screen.height - Input.mousePosition.y, Input.mousePosition.z)))
                    {
                        CheckEndRect = true;
                        PlayerKeyOrder.Add(i);
                        RectFlag = i;
                        print("EndContains");
                        break;
                    }
                    else
                    {
                        CheckEndRect = false;
                    }
                }

                if (CheckEndRect)
                {
                    Vector3 curPosition = centerPToLineRendererP(RectFlag);
                    DrawRenderLine(lineRendArray[lengthOfLineRenderer - 1], curPosition);
                }
                else
                {
                    PlayerKeyOrder.RemoveAt(PlayerKeyOrder.Count - 1);
                    Destroy(lineRendArray[lengthOfLineRenderer - 1].gameObject);
                    //lengthOfLineRenderer--;
                }

            }
        }        
    }

    void DrawRenderLine(LineRenderer line, Vector3 vect3)
    {
        Vector3 newPos = vect3;
        line.SetVertexCount(2);

        line.SetPosition(1, newPos);
        print("new point: " + newPos);
    }

    //public Vector2 RectCenterPoint(Rect AreaRect)       //计算一个Rect的中心点
    //{
    //    Vector2 CenterPoint=Vector2.zero;
    //    print("Rect:"+AreaRect);
    //    CenterPoint.x=AreaRect.xMin+AreaRect.width/2;
        
    //    CenterPoint.y=AreaRect.yMin+AreaRect.height/2;
    //    print("CenterPoint:"+CenterPoint);
    //    return CenterPoint;
    //}

    /// <summary>
    /// 鼠标所在位置转换为LineRenderer的位置
    /// </summary>
    /// <returns></returns>
    public Vector3 mousePToLineRendererP()      
    {
        screenPoint = Camera.main.WorldToScreenPoint(scanPos);
        Vector3 curScreenPoint = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z);
        Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint);
        print("curScreenPoint: " + curScreenPoint);
        print("curPosition: " + curPosition);
        return curPosition;
    }

    /// <summary>
    /// 鼠标所在区域的中心点转换为LineRenderer的位置
    /// </summary>
    /// <returns></returns>
    public Vector3 centerPToLineRendererP(int Flag)
    {
        screenPoint = Camera.main.WorldToScreenPoint(scanPos);
        Vector3 curScreenPoint = new Vector3(CenterPointList[Flag].x,Screen.height-CenterPointList[Flag].y,screenPoint.z);
        Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint);
        print("curScreenPoint: " + curScreenPoint);
        print("curPosition: " + curPosition);
        return curPosition;
    }
}

把touch.CS绑定在Camera上，设置如下：

 运行后可以任意点间连线，如图：