Unity3D的几种坐标系

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。

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。

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~）

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）。

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：



原文地址：http://www.cnblogs.com/martianzone/p/3371789.html