最近发现Mesh很牛的样子，虽然以前也见过人家大牛用这个写过工具，当时没大在意，现在开始接触，觉得挺好玩的，首先先上我画的几个图：
据说还可以画各种形状，原理就是所有图形都是由三角形组成的。
下面我们一一的解释下：
一.画三角形
首先，给组件添加MeshFilter和MeshRenderer两个组件，这两个组件是Mesh必须的，然后我们自己新建一个材质备用，用来给Mesh赋值使用，Mesh画出来图案的材质就是你你新建的材质。
重要的两步：
第一步：指定定点，比如我们画三角形，我们指定三个定点
第二部：指定三角形顺序，注意个triangles的数组的大小必须是3的倍数，然后三角形的点顺序必须是顺时针的，当然你逆时针只能在反面看到。
下面我们看下脚本：
void DrawTriangle()
{
gameObject.AddComponent<MeshFilter>();
gameObject.AddComponent<MeshRenderer>();
gameObject.GetComponent<MeshRenderer>().material = mat;
Mesh mesh = GetComponent<MeshFilter>().mesh;
mesh.Clear();
//设置顶点
mesh.vertices = new Vector3[] { new Vector3(0, 0, 0), new Vector3(0, 1, 0), new Vector3(1, 1, 0) };
//设置三角形顶点顺序，顺时针设置
mesh.triangles = new int[] { 0, 1, 2 };
}
最终图片如图所示：
三角形还是比较简单的，Unity官网API介绍就有这个实例，这里面我们暂时先不考虑UV.
二.画正方形
有了三角形，我们画正方形也会简单很多，我们分析一下正方形是由两个三角形组成的，我们画两个三角形就可以了，在上面的基础上我们再加一个点（1,0）就可以了，
代码如下：
#region 画正方形
void DrawSquare()
{
gameObject.AddComponent<MeshFilter>();
gameObject.AddComponent<MeshRenderer>();
gameObject.GetComponent<MeshRenderer>().material = mat;
Mesh mesh = GetComponent<MeshFilter>().mesh;
mesh.Clear();
mesh.vertices = new Vector3[] { new Vector3(0, 0, 0), new Vector3(0, 1, 0), new Vector3(1, 1, 0), new Vector3(1, 0, 0) };
mesh.triangles = new int[]
{ 0, 1, 2,
0, 2, 3
};
}
#endregion图形如图：
正方形能画，那什么梯形，平行四边形，菱形啥的肯定也不在话下，这里我就不写demo了。
三.画圆
一开始画圆还没啥头绪，后来想想，圆其实也是有很多个三角形组成的，类似这样：
鄙人画画比较丑，将就着看吧，类似这样可以细分成很多个小三角形，然后定点坐标就是各点组成：
顶点的集合有黄色的点组成，除了圆心，其它的点的坐标都是根据角度确定的，这个我们上学时几何学过，我就不细说了。
这样我们的画圆的函数需要参数有：半径，圆心坐标，分割的份数
顶点的代码如下：
//顶点
Vector3[] vertices = new Vector3[segments + 1];
vertices[0] = centerCircle;
float deltaAngle = Mathf.Deg2Rad * 360f / segments;
float currentAngle = 0;
for (int i = 1; i < vertices.Length; i++)
{
float cosA = Mathf.Cos(currentAngle);
float sinA = Mathf.Sin(currentAngle);
vertices[i] = new Vector3(cosA * radius + centerCircle.x, sinA * radius + centerCircle.y, 0);
currentAngle += deltaAngle;
}Deg2Rad相当于2PI
后面就是顶点的顺序了，注意，最后一个三角形的定点涉及到初始的点：
比如我们图中 的：
如图中所示，最后一组的时候如果使用遍历，数组会越界，所以我们可以最后三个单独写，也可以采用取模。
这里我们的代码采用单独写的方式，代码如下：
//三角形
int[] triangles = new int[segments * 3];
for (int i = 0, j = 1; i < segments * 3 - 3; i += 3, j++)
{
triangles[i] = 0;
triangles[i + 1] = j + 1;
triangles[i + 2] = j;
}
triangles[segments * 3 - 3] = 0;
triangles[segments * 3 - 2] = 1;
triangles[segments * 3 - 1] = segments;
这样我们的顶点和三角形都确定了，关于顺时针和逆时针，看你摄像头看的哪一面哈
完整的画圆代码如下：
#region 画圆
/// <summary>
/// 画圆
/// </summary>
/// <param name="radius">圆的半径</param>
/// <param name="segments">圆的分割数</param>
/// <param name="centerCircle">圆心得位置</param>
void DrawCircle(float radius, int segments, Vector3 centerCircle)
{
gameObject.AddComponent<MeshFilter>();
gameObject.AddComponent<MeshRenderer>();
gameObject.GetComponent<MeshRenderer>().material = mat;
//顶点
Vector3[] vertices = new Vector3[segments + 1];
vertices[0] = centerCircle;
float deltaAngle = Mathf.Deg2Rad * 360f / segments;
float currentAngle = 0;
for (int i = 1; i < vertices.Length; i++)
{
float cosA = Mathf.Cos(currentAngle);
float sinA = Mathf.Sin(currentAngle);
vertices[i] = new Vector3(cosA * radius + centerCircle.x, sinA * radius + centerCircle.y, 0);
currentAngle += deltaAngle;
}
//三角形
int[] triangles = new int[segments * 3];
for (int i = 0, j = 1; i < segments * 3 - 3; i += 3, j++)
{
triangles[i] = 0;
triangles[i + 1] = j + 1;
triangles[i + 2] = j;
}
triangles[segments * 3 - 3] = 0;
triangles[segments * 3 - 2] = 1;
triangles[segments * 3 - 1] = segments;
Mesh mesh = GetComponent<MeshFilter>().mesh;
mesh.Clear();
mesh.vertices = vertices;
mesh.triangles = triangles;
}
#endregion当然你还可以做点小变动，画成这样：
上面的毁了，这样的就自然能画出来，自己试下哈。
四.画圆环
既然，上面的圆画出来了，圆环也就在此基础上，只不过有好多小梯形组成，梯形由两个三角形组成。
示意图如下：
当分成很多等份时，就类似圆环了。
同理，我们先列顶点，这一次我们比上面多要一个参数，内圆半径：
顶点代码如下：
//顶点
Vector3[] vertices = new Vector3[segments * 2];
float deltaAngle = Mathf.Deg2Rad * 360f / segments;
float currentAngle = 0;
for (int i = 0; i < vertices.Length; i += 2)
{
float cosA = Mathf.Cos(currentAngle);
float sinA = Mathf.Sin(currentAngle);
vertices[i] = new Vector3(cosA * innerRadius + centerCircle.x, sinA * innerRadius + centerCircle.y, 0);
vertices[i + 1] = new Vector3(cosA * radius + centerCircle.x, sinA * radius + centerCircle.y, 0);
currentAngle += deltaAngle;
}同理，再列出三角形：
//三角形
int[] triangles = new int[segments * 6];
for (int i = 0, j = 0; i < segments * 6; i += 6, j += 2)
{
triangles[i] = j;
triangles[i + 1] = (j + 1) % vertices.Length;
triangles[i + 2] = (j + 3) % vertices.Length;
triangles[i + 3] = j;
triangles[i + 4] = (j + 3) % vertices.Length;
triangles[i + 5] = (j + 2) % vertices.Length;
}
最终结果如图：
完整的代码如下：
#region 画圆环
/// <summary>
/// 画圆环
/// </summary>
/// <param name="radius">圆半径</param>
/// <param name="innerRadius">内圆半径</param>
/// <param name="segments">圆的分个数</param>
/// <param name="centerCircle">圆心坐标</param>
void DrawRing(float radius, float innerRadius, int segments, Vector3 centerCircle)
{
gameObject.AddComponent<MeshFilter>();
gameObject.AddComponent<MeshRenderer>();
gameObject.GetComponent<MeshRenderer>().material = mat;
//顶点
Vector3[] vertices = new Vector3[segments * 2];
float deltaAngle = Mathf.Deg2Rad * 360f / segments;
float currentAngle = 0;
for (int i = 0; i < vertices.Length; i += 2)
{
float cosA = Mathf.Cos(currentAngle);
float sinA = Mathf.Sin(currentAngle);
vertices[i] = new Vector3(cosA * innerRadius + centerCircle.x, sinA * innerRadius + centerCircle.y, 0);
vertices[i + 1] = new Vector3(cosA * radius + centerCircle.x, sinA * radius + centerCircle.y, 0);
currentAngle += deltaAngle;
}
//三角形
int[] triangles = new int[segments * 6];
for (int i = 0, j = 0; i < segments * 6; i += 6, j += 2)
{
triangles[i] = j;
triangles[i + 1] = (j + 1) % vertices.Length;
triangles[i + 2] = (j + 3) % vertices.Length;
triangles[i + 3] = j;
triangles[i + 4] = (j + 3) % vertices.Length;
triangles[i + 5] = (j + 2) % vertices.Length;
}
Mesh mesh = GetComponent<MeshFilter>().mesh;
mesh.Clear();
mesh.vertices = vertices;
mesh.triangles = triangles;
}
#endregion一样，代码做点小的改动就能产生太阳和锯齿的图片，如下：
怎么改的上面看明白的一眼就看出来了，哈哈，你们自己写吧。
五：完整代码
本篇博客涉及的脚本的完整代码如下：
using UnityEngine;
using System.Collections;
public enum PlaneState
{
Triangle,
Square,
Circle,
Ring
}
public class Test : MonoBehaviour
{
public Material mat;
public PlaneState planeState;
// Use this for initialization
void Start()
{
switch (planeState)
{
case PlaneState.Triangle:
DrawTriangle();
break;
case PlaneState.Square:
DrawSquare();
break;
case PlaneState.Circle:
DrawCircle(2, 50, Vector3.zero);
break;
case PlaneState.Ring:
DrawRing(2, 3, 50, Vector3.zero);
break;
}
}
#region 画三角形
void DrawTriangle()
{
gameObject.AddComponent<MeshFilter>();
gameObject.AddComponent<MeshRenderer>();
gameObject.GetComponent<MeshRenderer>().material = mat;
Mesh mesh = GetComponent<MeshFilter>().mesh;
mesh.Clear();
//设置顶点
mesh.vertices = new Vector3[] { new Vector3(0, 0, 0), new Vector3(0, 1, 0), new Vector3(1, 1, 0) };
//设置三角形顶点顺序，顺时针设置
mesh.triangles = new int[] { 0, 1, 2 };
}
#endregion
#region 画正方形
void DrawSquare()
{
gameObject.AddComponent<MeshFilter>();
gameObject.AddComponent<MeshRenderer>();
gameObject.GetComponent<MeshRenderer>().material = mat;
Mesh mesh = GetComponent<MeshFilter>().mesh;
mesh.Clear();
mesh.vertices = new Vector3[] { new Vector3(0, 0, 0), new Vector3(0, 1, 0), new Vector3(1, 1, 0), new Vector3(1, 0, 0) };
mesh.triangles = new int[]
{ 0, 1, 2,
0, 2, 3
};
}
#endregion
#region 画圆
/// <summary>
/// 画圆
/// </summary>
/// <param name="radius">圆的半径</param>
/// <param name="segments">圆的分割数</param>
/// <param name="centerCircle">圆心得位置</param>
void DrawCircle(float radius, int segments, Vector3 centerCircle)
{
gameObject.AddComponent<MeshFilter>();
gameObject.AddComponent<MeshRenderer>();
gameObject.GetComponent<MeshRenderer>().material = mat;
//顶点
Vector3[] vertices = new Vector3[segments + 1];
vertices[0] = centerCircle;
float deltaAngle = Mathf.Deg2Rad * 360f / segments;
float currentAngle = 0;
for (int i = 1; i < vertices.Length; i++)
{
float cosA = Mathf.Cos(currentAngle);
float sinA = Mathf.Sin(currentAngle);
vertices[i] = new Vector3(cosA * radius + centerCircle.x, sinA * radius + centerCircle.y, 0);
currentAngle += deltaAngle;
}
//三角形
int[] triangles = new int[segments * 3];
for (int i = 0, j = 1; i < segments * 3 - 3; i += 3, j++)
{
triangles[i] = 0;
triangles[i + 1] = j + 1;
triangles[i + 2] = j;
}
triangles[segments * 3 - 3] = 0;
triangles[segments * 3 - 2] = 1;
triangles[segments * 3 - 1] = segments;
Mesh mesh = GetComponent<MeshFilter>().mesh;
mesh.Clear();
mesh.vertices = vertices;
mesh.triangles = triangles;
}
#endregion
#region 画圆环
/// <summary>
/// 画圆环
/// </summary>
/// <param name="radius">圆半径</param>
/// <param name="innerRadius">内圆半径</param>
/// <param name="segments">圆的分个数</param>
/// <param name="centerCircle">圆心坐标</param>
void DrawRing(float radius, float innerRadius, int segments, Vector3 centerCircle)
{
gameObject.AddComponent<MeshFilter>();
gameObject.AddComponent<MeshRenderer>();
gameObject.GetComponent<MeshRenderer>().material = mat;
//顶点
Vector3[] vertices = new Vector3[segments * 2];
float deltaAngle = Mathf.Deg2Rad * 360f / segments;
float currentAngle = 0;
for (int i = 0; i < vertices.Length; i += 2)
{
float cosA = Mathf.Cos(currentAngle);
float sinA = Mathf.Sin(currentAngle);
vertices[i] = new Vector3(cosA * innerRadius + centerCircle.x, sinA * innerRadius + centerCircle.y, 0);
vertices[i + 1] = new Vector3(cosA * radius + centerCircle.x, sinA * radius + centerCircle.y, 0);
currentAngle += deltaAngle;
}
//三角形
int[] triangles = new int[segments * 6];
for (int i = 0, j = 0; i < segments * 6; i += 6, j += 2)
{
triangles[i] = j;
triangles[i + 1] = (j + 1) % vertices.Length;
triangles[i + 2] = (j + 3) % vertices.Length;
triangles[i + 3] = j;
triangles[i + 4] = (j + 3) % vertices.Length;
triangles[i + 5] = (j + 2) % vertices.Length;
}
Mesh mesh = GetComponent<MeshFilter>().mesh;
mesh.Clear();
mesh.vertices = vertices;
mesh.triangles = triangles;
}
#endregion
}