Unity3D点击绘制二维模型线和三维模型线

下面是转载别人的，缺点是只能在xz平面上画线，可以添加一个地板来测试，鼠标点击地板进行画线

这两天在研究画线的东西。直到昨天才小有成效。拿出来和大家分享一下。先上图：

以前曾经尝试过用LineRender写画线的功能，但是在拐弯的时候会出现变形和扭曲。所以才决定用绘制Mesh的方法写一个画线的功能。

东西其实很简单，稍微有一点数学的知识，用到了三角函数。还有一些关于构造Mesh的相关代码。下面有草图一张：

黑色的线框代表画出来的模型线，PointA和PointB代表获取的起始点和终结点，A,B,C,D为Mesh的四个顶点。

已知起始点和终结点和线宽，就可以求出四个顶点的坐标。并根据这四个顶点绘制出Mesh.

至于具体的实现细节，大家看代码吧。

DrawMeshLine类：

[csharp]  view plain  copy

1. using UnityEngine;  
2. using System.Collections;  
3. using System.Collections.Generic;  
4.   
5. public class DrawMeshLine : MonoBehaviour   
6. {  
7.     //线容器  
8.     List<Vector3> LinePointContainer;  
9.     //线宽  
10.     public float LineWidth = 0.5f;  
11.     //地形层  
12.     public int Layer = 8;  
13.     //线物体父物体  
14.     GameObject LineObj;  
15.       
16.     void Start ()   
17.     {  
18.         LinePointContainer = new List<Vector3>();  
19.         LineObj = new GameObject("Lines");  
20.     }  
21.       
22.     void Update ()   
23.     {  
24.         if(Input.GetMouseButtonDown(0))  
25.         {  
26.             Ray ray = Camera.mainCamera.ScreenPointToRay(Input.mousePosition);  
27.             RaycastHit hit;  
28.             if(Physics.Raycast(ray,out hit))  
29.             {  
30.                 if(hit.transform.gameObject.layer != Layer)return;  
31.                 LinePointContainer.Add(hit.point);  
32.             }  
33.             if(LinePointContainer.Count == 1)  
34.             {  
35.                 //二维初始面片圆  
36. //              GameObject sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);  
37. //              sphere.transform.parent = LineObj.transform;  
38. //              sphere.transform.position = hit.point;  
39. //              sphere.transform.localScale = new Vector3(LineWidth * 2,0.01f,LineWidth * 2);  
40. //              sphere.renderer.material.shader = Shader.Find("GUI/Text Shader");  
41. //              sphere.renderer.material.SetColor("_Color",new Color(255,0,0,255) / 255);  
42.                   
43.                 //三维初始球  
44.                 GameObject sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);  
45.                 sphere.transform.parent = LineObj.transform;  
46.                 sphere.transform.position = new Vector3(hit.point.x,hit.point.y + LineWidth,hit.point.z);  
47.                 sphere.transform.localScale = new Vector3(LineWidth * Mathf.Sqrt(8.0f),LineWidth * Mathf.Sqrt(8.0f),LineWidth * Mathf.Sqrt(8.0f));  
48.             }  
49.             if(LinePointContainer.Count > 1)  
50.             {  
51.                 //画二维面片线  
52.                 //DrawLine2D(LinePointContainer[LinePointContainer.Count - 2],LinePointContainer[LinePointContainer.Count - 1]);  
53.                 //画三维立体线  
54.                 DrawLine3D(LinePointContainer[LinePointContainer.Count - 2],LinePointContainer[LinePointContainer.Count - 1]);                   //第一个参数是起点，第二个参数是终点
55.             }  
56.         }  
57.         if(Input.GetMouseButtonDown(1))  
58.         {  
59.             //清空线容器  
60.             if(LinePointContainer.Count < 3)return;  
61.             DrawLine3D(LinePointContainer[LinePointContainer.Count - 1],LinePointContainer[0]);  
62.             LinePointContainer.Clear();  
63.         }  
64.         if(Input.GetKeyDown(KeyCode.Escape))  
65.         {  
66.             //清除所有线物体  
67.             LinePointContainer.Clear();  
68.             ClearLineObjects();  
69.         }  
70.     }  
71.       
72.     /// <summary>  
73.     /// 二维线  
74.     /// </summary>  
75.     /// <param name='PointA'>  
76.     /// 初始点  
77.     /// </param>  
78.     /// <param name='PointB'>  
79.     /// 结束点  
80.     /// </param>  
81.     void DrawLine2D(Vector3 PointA,Vector3 PointB)  
82.     {  
83.         float HorDisABx = PointB.x - PointA.x;  
84.         float HorDisABz = PointB.z - PointA.z;  
85.         float HorDisAB = Mathf.Sqrt(Mathf.Pow(HorDisABx,2) + Mathf.Pow(HorDisABz,2));  
86.           
87.         float offsetX = HorDisABz * LineWidth / HorDisAB;  
88.         float offsetZ = HorDisABx * LineWidth / HorDisAB;  
89.           
90.         Vector3 Point1 = new Vector3(PointA.x - offsetX,PointA.y,PointA.z + offsetZ);  
91.         Vector3 Point2 = new Vector3(PointA.x + offsetX,PointA.y,PointA.z - offsetZ);  
92.         Vector3 Point3 = new Vector3(PointB.x + offsetX,PointB.y,PointB.z - offsetZ);  
93.         Vector3 Point4 = new Vector3(PointB.x - offsetX,PointB.y,PointB.z + offsetZ);  
94.           
95.  
96. 
    
97.           
98.         GameObject go = new GameObject((LinePointContainer.Count - 1).ToString());  
99.         go.transform.parent = LineObj.transform;  
100.         Mesh mesh = go.AddComponent<MeshFilter>().mesh;  
101.         go.AddComponent<MeshRenderer>();  
102.         mesh.vertices = new Vector3[]{Point1,Point2,Point3,Point4};  
103.         mesh.triangles = new int[]{2,1,0,0,3,2};  
104.           
105.         GameObject sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);  
106.         sphere.transform.parent = LineObj.transform;  
107.         sphere.transform.position = PointB;  
108.         sphere.transform.localScale = new Vector3(LineWidth * 2,0.01f,LineWidth * 2);  
109.     }  
110.       
111.     /// <summary>  
112.     /// 三维线  
113.     /// </summary>  
114.     /// <param name='PointA'>  
115.     /// 初始点  
116.     /// </param>  
117.     /// <param name='PointB'>  
118.     /// 结束点  
119.     /// </param>  
120.     void DrawLine3D(Vector3 PointA,Vector3 PointB)  
121.     {  
122.         float HorDisABx = PointB.x - PointA.x;  
123.         float HorDisABz = PointB.z - PointA.z;  
124.         float HorDisAB = Mathf.Sqrt(Mathf.Pow(HorDisABx,2) + Mathf.Pow(HorDisABz,2));  //求起点和终点的模长
125.           
126.         float offsetX = HorDisABz * LineWidth / HorDisAB;  
127.         float offsetZ = HorDisABx * LineWidth / HorDisAB;  
128.           
129.         Vector3 Point1 = new Vector3(PointA.x - offsetX,PointA.y,PointA.z + offsetZ);  
130.         Vector3 Point2 = new Vector3(PointA.x + offsetX,PointA.y,PointA.z - offsetZ);  
131.         Vector3 Point3 = new Vector3(PointB.x + offsetX,PointB.y,PointB.z - offsetZ);  
132.         Vector3 Point4 = new Vector3(PointB.x - offsetX,PointB.y,PointB.z + offsetZ);  
133.           
134.         GameObject go1 = new GameObject((LinePointContainer.Count - 1).ToString() + "_1");  
135.         go1.transform.parent = LineObj.transform;  
136.         Mesh mesh1 = go1.AddComponent<MeshFilter>().mesh;  
137.         go1.AddComponent<MeshRenderer>();  
138.         mesh1.vertices = new Vector3[]{Point1,Point2,Point3,Point4};  
139.         mesh1.triangles = new int[]{2,1,0,0,3,2};  
140.           
141.         Vector3 Point5 = new Vector3(PointA.x - offsetX,PointA.y + 2 * LineWidth,PointA.z + offsetZ);  
142.         Vector3 Point6 = new Vector3(PointA.x + offsetX,PointA.y + 2 * LineWidth,PointA.z - offsetZ);  
143.         Vector3 Point7 = new Vector3(PointB.x + offsetX,PointB.y + 2 * LineWidth,PointB.z - offsetZ);  
144.         Vector3 Point8 = new Vector3(PointB.x - offsetX,PointB.y + 2 * LineWidth,PointB.z + offsetZ);  
145.           
146.         GameObject go2 = new GameObject((LinePointContainer.Count - 1).ToString() + "_2");  
147.         go2.transform.parent = LineObj.transform;  
148.         Mesh mesh2 = go2.AddComponent<MeshFilter>().mesh;  
149.         go2.AddComponent<MeshRenderer>();  
150.         mesh2.vertices = new Vector3[]{Point5,Point6,Point7,Point8};  
151.         mesh2.triangles = new int[]{2,1,0,0,3,2};  
152.           
153.         GameObject go3 = new GameObject((LinePointContainer.Count - 1).ToString() + "_3");  
154.         go3.transform.parent = LineObj.transform;  
155.         Mesh mesh3 = go3.AddComponent<MeshFilter>().mesh;  
156.         go3.AddComponent<MeshRenderer>();  
157.         mesh3.vertices = new Vector3[]{Point6,Point2,Point3,Point7};  
158.         mesh3.triangles = new int[]{2,1,0,0,3,2};  
159.           
160.         GameObject go4 = new GameObject((LinePointContainer.Count - 1).ToString() + "_4");  
161.         go4.transform.parent = LineObj.transform;  
162.         Mesh mesh4 = go4.AddComponent<MeshFilter>().mesh;  
163.         go4.AddComponent<MeshRenderer>();  
164.         mesh4.vertices = new Vector3[]{Point1,Point5,Point8,Point4};  
165.         mesh4.triangles = new int[]{2,1,0,0,3,2};  
166.           
167.         GameObject sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);  
168.         sphere.transform.parent = LineObj.transform;  
169.         sphere.transform.position = new Vector3(PointB.x,PointB.y + LineWidth,PointB.z);  
170.         sphere.transform.localScale = new Vector3(LineWidth * Mathf.Sqrt(8.0f),LineWidth * Mathf.Sqrt(8.0f),LineWidth * Mathf.Sqrt(8.0f));  
171.     }  
172.       
173.     void ClearLineObjects ()  
174.     {  
175.         for(int i = 0 ; i < LineObj.transform.childCount;i ++)  
176.         {  
177.             GameObject go = LineObj.transform.GetChild(i).gameObject;  
178.             Destroy(go);  
179.         }  
180.     }  
181. }  

个人理解：

想象成一个几何体，以ABCD为地面，把地面抬高2 * LineWidth,PointA.z米作为顶面EFGH

1 GameObject go1 = new GameObject((LinePointContainer.Count - 1).ToString() + "_1"); 这个是画面ABCD

2 GameObject go2 = new GameObject((LinePointContainer.Count - 1).ToString() + "_2");  这个是画面EFGH

3 GameObject go3 = new GameObject((LinePointContainer.Count - 1).ToString() + "_3");  这个是画面BCGF

4  GameObject go4 = new GameObject((LinePointContainer.Count - 1).ToString() + "_4");  这个是画面ADHE

其中面ABFE和面DCGH不用画，画了也没有意义