Mesh网格编程（二） 万能网格几何体

具体思路：

通过Mesh网格编程实现几何体的多种变化。以立体五角星为例，大边长和小边长分别设置长度为5的数组，数组控制几何体顶层空心，顶层大小，中间层大小，底层大小，底层空心。通过循环构建上层与下层之间的网格。

效果图：

实现代码：

using UnityEngine;
using System.Collections;

public class Star3 : MonoBehaviour {
	
	Mesh mesh;

	public bool sophisticated = false;		//圆滑曲面
	public bool star = true;				//星形
	public int line = 5;					//边数
	public float[] maxsize = {0,0,5,0,0};	//外角大小
	public float[] minSize = {0,0,1,0,0};	//内角大小
	public float high = 1;					//高度
	public float low = -1;					//低度
	
	private Vector3[] vs;					//顶点坐标
	private int[] ts;						//顶点序列
	private Vector2[] newUVs;				//UV贴图
	private Vector3[] newNormals;			//法线
	
	// Update is called once per frame
	void Update () {
		//变量约束
		line = Mathf.Clamp (line, 2, 300);
		high = Mathf.Clamp (high, low, high);
		low = Mathf.Clamp (low, low, high);
		if (!star) {
			for (int i = 0; i < 5; i++) {
				minSize[i] = Mathf.Cos(Mathf.PI / line) * maxsize[i];
			}
		}
		for (int i = 1; i < 4; i++) {
			maxsize[i] = Mathf.Clamp (maxsize[i], 0, maxsize[i]);
			minSize[i] = Mathf.Clamp (minSize[i], 0, maxsize[i]);
		}
		maxsize[0] = Mathf.Clamp (maxsize[0], 0, maxsize[1]);
		minSize[0] = Mathf.Clamp (minSize[0], 0, minSize[1]);
		maxsize[4] = Mathf.Clamp (maxsize[4], 0, maxsize[3]);
		minSize[4] = Mathf.Clamp (minSize[4], 0, minSize[3]);
		//角度计算
		float corner = 2 * Mathf.PI / line;
		//确定顶点数量
		int temp = 5 * 4 * 3 * line;
		
		vs = new Vector3[temp];
		ts = new int[temp];
		newUVs = new Vector2[temp];
		newNormals = new Vector3[temp];

		int count = 0;
		float h = 0;
		float l = 0;
		for (int i = 0; i < 5; i++) {
			switch (i) {
			case 0: 
				h = high;
				l = high;
				break;
			case 1:
				h = high;
				l = 0;
				break;
			case 2:
				h = 0;
				l = low;
				break;
			case 3:
				h = low;
				l = low;
				break;
			case 4:
				h = low;
				l = high;
				break;
			}
			for (int k = 0; k < line; k++) {
				//确定顶点坐标
				vs[count] = new Vector3(Mathf.Sin(k * corner) * maxsize[i],Mathf.Cos(k * corner) * maxsize[i],h);
				vs[count + 1] = new Vector3(Mathf.Sin((k + 0.5f) * corner) * minSize[(i + 1) % 5],Mathf.Cos((k + 0.5f) * corner) * minSize[(i + 1) % 5],l);
				vs[count + 2] = new Vector3(Mathf.Sin(k * corner) * maxsize[(i + 1) % 5],Mathf.Cos(k * corner) * maxsize[(i + 1) % 5],l);

				vs[count + 3] = new Vector3(Mathf.Sin(k * corner) * maxsize[i],Mathf.Cos(k * corner) * maxsize[i],h);
				vs[count + 4] = new Vector3(Mathf.Sin((k + 0.5f) * corner) * minSize[i],Mathf.Cos((k + 0.5f) * corner) * minSize[i],h);
				vs[count + 5] = new Vector3(Mathf.Sin((k + 0.5f) * corner) * minSize[(i + 1) % 5],Mathf.Cos((k + 0.5f) * corner) * minSize[(i + 1) % 5],l);

				vs[count + 6] = new Vector3(Mathf.Sin(k * corner) * maxsize[i],Mathf.Cos(k * corner) * maxsize[i],h);
				vs[count + 7] = new Vector3(Mathf.Sin(k * corner) * maxsize[(i + 1) % 5],Mathf.Cos(k * corner) * maxsize[(i + 1) % 5],l);
				vs[count + 8] = new Vector3(Mathf.Sin((k - 0.5f) * corner) * minSize[(i + 1) % 5],Mathf.Cos((k - 0.5f) * corner) * minSize[(i + 1) % 5],l);

				vs[count + 9] = new Vector3(Mathf.Sin(k * corner) * maxsize[i],Mathf.Cos(k * corner) * maxsize[i],h);
				vs[count + 10] = new Vector3(Mathf.Sin((k - 0.5f) * corner) * minSize[(i + 1) % 5],Mathf.Cos((k - 0.5f) * corner) * minSize[(i + 1) % 5],l);
				vs[count + 11] = new Vector3(Mathf.Sin((k - 0.5f) * corner) * minSize[i],Mathf.Cos((k - 0.5f) * corner) * minSize[i],h);
				//确定法线
				if (sophisticated) {
					newNormals[count] = Vector3.Normalize(vs[count] - new Vector3(0,0,h));
					newNormals[count + 1] = Vector3.Normalize(vs[count + 1] - new Vector3(0,0,l));
					newNormals[count + 2] = Vector3.Normalize(vs[count + 2] - new Vector3(0,0,l));
					newNormals[count + 3] = Vector3.Normalize(vs[count + 3] - new Vector3(0,0,h));
					newNormals[count + 4] = Vector3.Normalize(vs[count + 4] - new Vector3(0,0,h));
					newNormals[count + 5] = Vector3.Normalize(vs[count + 5] - new Vector3(0,0,l));
					newNormals[count + 6] = Vector3.Normalize(vs[count + 6] - new Vector3(0,0,h));
					newNormals[count + 7] = Vector3.Normalize(vs[count + 7] - new Vector3(0,0,l));
					newNormals[count + 8] = Vector3.Normalize(vs[count + 8] - new Vector3(0,0,l));
					newNormals[count + 9] = Vector3.Normalize(vs[count + 9] - new Vector3(0,0,h));
					newNormals[count + 10] = Vector3.Normalize(vs[count + 10] - new Vector3(0,0,l));
					newNormals[count + 11] = Vector3.Normalize(vs[count + 11] - new Vector3(0,0,h));
				} else {
					for (int j = 0; j < 4; j++) {
						Vector3 newNormal = Vector3.Cross(vs[count + 3 * j + 1] - vs[count + 3 * j + 0],vs[count + 3 * j + 2] - vs[count + 3 * j + 0]);
						for (int z = 0; z < 3; z++) {
							newNormals[count + 3 * j + z] = Vector3.Normalize(newNormal);
						}
					}
				}

				count += 12;
				}
		}
		//确定顶点序列
		for (int i = 0; i < ts.Length; i++) {
			ts[i] = i;
		}
		//创建网格
		mesh = new Mesh();
		GetComponent().mesh = mesh;
		mesh.vertices = vs;
		mesh.uv = newUVs;
		mesh.triangles = ts;
		mesh.normals = newNormals;

	}
}

通过调节变量图中几何体均可实现。Mesh编程步骤见 Mesh网格编程（一）。