Unity3D动态生成平面网格

在编写几何着色器的时候发现默认的plane无法满足需求，并且顶点顺序未知，于是便写了一个网格生成代码，便于生成指定大小的plane，且顶点顺序可控。

效果如下：

一个单元格由4个顶点，两个三角面组成。

四个顶点如下图

则生成面的顶点顺序为：

左上三角形：0 -> 1 -> 2
右下三角形：2 -> 3 -> 0

unity中顺时针绘制为正面，逆时针绘制为反面。

实现脚本如下：

//planebuilder.cs

using system.collections;
using system.collections.generic;
using unityengine;

#region editor

#if unity_editor

using unityeditor;

[customeditor(typeof(planebuilder))]
public class planebuildereditor : editor
{
 public override void oninspectorgui()
 {
 planebuilder builder = (planebuilder)target;

 editorgui.beginchangecheck();

 base.oninspectorgui();

 if (editorgui.endchangecheck())
 {
  builder.updatemesh();
 }

 if (guilayout.button("更新网格"))
 {
  builder.updatemesh();
 }
 }
}

#endif

#endregion editor

[requirecomponent(typeof(meshfilter), typeof(meshrenderer))]
public class planebuilder : monobehaviour
{
 [serializefield]
 private meshfilter _meshfilter;

 [serializefield]
 private meshrenderer _meshrenderer;

 /// <summary>
 /// 单元格大小
 /// </summary>
 [serializefield]
 private vector2 _cellsize = new vector2(1, 1);

 /// <summary>
 /// 网格大小
 /// </summary>
 [serializefield]
 private vector2int _gridsize = new vector2int(2, 2);

 public meshrenderer meshrenderer
 {
 get
 {
  return _meshrenderer;
 }
 }

 public meshfilter meshfilter
 {
 get
 {
  return _meshfilter;
 }
 }

 private void awake()
 {
 _meshfilter = getcomponent<meshfilter>();
 _meshrenderer = getcomponent<meshrenderer>();
 updatemesh();
 }

 public void updatemesh()
 {
 mesh mesh = new mesh();

 //计算plane大小
 vector2 size;
 size.x = _cellsize.x * _gridsize.x;
 size.y = _cellsize.y * _gridsize.y;

 //计算plane一半大小
 vector2 halfsize = size / 2;

 //计算顶点及uv
 list<vector3> vertices = new list<vector3>();
 list<vector2> uvs = new list<vector2>();

 vector3 vertice = vector3.zero;
 vector2 uv = vector3.zero;

 for (int y = 0; y < _gridsize.y + 1; y++)
 {
  vertice.z = y * _cellsize.y - halfsize.y;//计算顶点y轴
  uv.y = y * _cellsize.y / size.y;//计算顶点纹理坐标v

  for (int x = 0; x < _gridsize.x + 1; x++)
  {
  vertice.x = x * _cellsize.x - halfsize.x;//计算顶点x轴
  uv.x = x * _cellsize.x / size.x;//计算顶点纹理坐标u

  vertices.add(vertice);//添加到顶点数组
  uvs.add(uv);//添加到纹理坐标数组
  }
 }

 //顶点序列
 int a = 0;
 int b = 0;
 int c = 0;
 int d = 0;
 int startindex = 0;
 int[] indexs = new int[_gridsize.x * _gridsize.y * 2 * 3];//顶点序列
 for (int y = 0; y < _gridsize.y; y++)
 {
  for (int x = 0; x < _gridsize.x; x++)
  {
  //四边形四个顶点
  a = y * (_gridsize.x + 1) + x;//0
  b = (y + 1) * (_gridsize.x + 1) + x;//1
  c = b + 1;//2
  d = a + 1;//3

  //计算在数组中的起点序号
  startindex = y * _gridsize.x * 2 * 3 + x * 2 * 3;

  //左上三角形
  indexs[startindex] = a;//0
  indexs[startindex + 1] = b;//1
  indexs[startindex + 2] = c;//2

  //右下三角形
  indexs[startindex + 3] = c;//2
  indexs[startindex + 4] = d;//3
  indexs[startindex + 5] = a;//0
  }
 }

 //
 mesh.setvertices(vertices);//设置顶点
 mesh.setuvs(0, uvs);//设置uv
 mesh.setindices(indexs, meshtopology.triangles, 0);//设置顶点序列
 mesh.recalculatenormals();
 mesh.recalculatebounds();
 mesh.recalculatetangents();

 _meshfilter.mesh = mesh;
 }

#if unity_editor

 private void onvalidate()
 {
 if (null == _meshfilter)
 {
  _meshfilter = getcomponent<meshfilter>();
 }
 if (null == _meshrenderer)
 {
  _meshrenderer = getcomponent<meshrenderer>();
  if (null == _meshrenderer.sharedmaterial)
  {
  _meshrenderer.sharedmaterial = new material(shader.find("standard"));
  }
 }
 }

#endif
}

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