Unity3D生成一段隧道网格 Unity3D生成一段隧道网格的方法

时间:2021-02-03 三体问题人气:0

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一、需求

最近有一个需求，生成段隧道的骨架网格。目前想到的方法就是，获取隧道网格，通过一个算法分离内框和外框的点：

然后通过外框和内框上的点画线，可以通过深度优先搜索得到内外两个环的序列，从而实现骨架网格

二、生成隧道算法

隧道由段圆弧和一条直线组成，所以算法如下：

1、取圆心为0，0，0，和圆上半径的向量 \underset{OB}{\rightarrow} ，绕z轴，旋转向量\underset{OB}{\rightarrow}，取到圆上的点，外框上的点同理可得

2、平移内外框上的点，z轴加上偏离，得到隧道另一端的点

3、取相邻外框上的点和平移后的四个点，生成两个三角形。内框同理可得。

三、效果如下：

四、实现：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
 
public class MeshCreater : MonoBehaviour
{
 Mesh mesh;
 public Material mat;//mesh材质
 public GameObject game;
 
 // Start is called before the first frame update
 void Start()
 {
 mesh = new Mesh();
 mesh.Clear();
 SetVertivesUV();
 SetTriangles();
 mesh.vertices = vertices.ToArray();
 mesh.triangles = triangles;
 GameObject obj_cell = new GameObject();
 obj_cell.name = "cell";
 
 mesh.RecalculateNormals();//重置法线
 
 mesh.RecalculateBounds(); //重置范围
 
 obj_cell.AddComponent<MeshFilter>().mesh = mesh;
 obj_cell.AddComponent<MeshRenderer>();
 obj_cell.GetComponent<MeshRenderer>().material = mat;
 
 MeshCaluate mesh_caluate = new MeshCaluate();
 mesh_caluate.CalculateMesh(mesh);
 }
 
 // Update is called once per frame
 void Update()
 {
 
 }
 
 public List<Vector3> vertices = new List<Vector3>();
 
 private float angle = 10;
 
 private float max_angle = 120;
 // 设置顶点信息
 void SetVertivesUV()
 {
 Vector3 dir1 = new Vector3(Mathf.Sqrt(3f), -1, 0);
 Vector3 dir2 = dir1 * 0.8f;
 
 List<Vector3> points1 = new List<Vector3>();
 List<Vector3> points2 = new List<Vector3>();
 
 int count = (int)((360 - max_angle) / angle);
 
 for (int i = 0; i < count; i++)
 {
  Quaternion q= Quaternion.AngleAxis(i * angle, Vector3.forward);
  
  Vector3 point1 = q* dir1;
  Vector3 point2 = q* dir2;
  points1.Add(point1);
  points2.Add(point2);
 }
 points1.Add(points1[0]);
 points2.Add(points2[0]);
 
 for (int i = 0; i < points1.Count; i++)
 {
  var v1 = points1[i];
  var v2 = points2[i];
  var v3 = points1[i];
  v3.z = 10;
  var v4 = points2[i];
  v4.z = 10;
  
  vertices.Add(v1);
  vertices.Add(v3);
  vertices.Add(v2);
  vertices.Add(v4);
 }
 }
 
 private int[] triangles;//索引
 // 设置索引
 void SetTriangles()
 {
 triangles = new int[vertices.Count * 3];
 int c = 0;
 for (int i = 0; i < triangles.Length -12 ; i += 12)
 {
  var v1 = c;
  var v2 = c + 1;
  var v3 = c + 4;
  var v4 = c + 5;
  
  var v5 = c + 2;
  var v6 = c + 3;
  var v7 = c + 6;
  var v8 = c + 7;
  
  triangles[i] = v4;
  triangles[i + 1] = v2;
  triangles[i + 2] = v1;
 
  triangles[i + 3] = v3;
  triangles[i + 4] = v4;
  triangles[i + 5] = v1;
 
  triangles[i + 6] = v5;
  triangles[i + 7] = v6;
  triangles[i + 8] = v8;
  
  triangles[i + 9] = v5;
  triangles[i + 10] = v8;
  triangles[i + 11] = v7;
 
  c += 4;
 }
 }
}

五、缺陷

UV未计算，所以使用贴图时有问题

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