Unity-绘制圆环

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/qq826364410/article/details/86584186

using UnityEditor;
using UnityEngine;

[RequireComponent(typeof(MeshRenderer), typeof(MeshFilter))]
public class RingMesh : MonoBehaviour
{
    //分区
    private int segments = 50;
    //半径
    private int radius = 5;
    //内半径
    private int interRadius = 3;
    private MeshRenderer m_MeshRender;
    private MeshFilter m_MeshFilter;

    // Use this for initialization
    void Start()
    {
        m_MeshRender = GetComponent<MeshRenderer>();
        m_MeshFilter = GetComponent<MeshFilter>();
        m_MeshRender.material = CreateMaterial();
        m_MeshFilter.mesh = CreateMesh();

        MeshFilter[] filter = GetComponentsInChildren<MeshFilter>();
        foreach (var item in filter)
        {
            Debug.Log(item.name);
        }
    }

    private Mesh CreateMesh()
    {
        Mesh mesh = new Mesh();
        //因为要形成闭环，多加两个顶点，方便计算三角形，跟索引0,1的顶点是重合的
        int vertexLen = segments * 2 + 2;
        //把这个度数改成其他度数，就可以绘制成环形扇面了
        int degree = 60;
        float angle = degree * Mathf.Deg2Rad;
        float curAngle = angle / 2;
        float deltaAngle = angle / segments;

        //形成圆环，可以绘制一圈等腰梯形。等腰梯形，可以由两个三角形组成。
        Vector3[] vertex = new Vector3[vertexLen];
        for (int i = 0; i < vertexLen; i += 2)
        {
            float cos = Mathf.Cos(curAngle);
            float sin = Mathf.Sin(curAngle);
            vertex[i] = new Vector3(cos * interRadius, 0, sin * interRadius);
            vertex[i + 1] = new Vector3(cos * radius, 0, sin * radius);
            //为了绘制圆形，当前的角度不断递减
            curAngle -= deltaAngle;
        }
        //填充三角形
        //三角形的顶点索引总数，三角形数目 * 3，下面相当于segments * 2 * 3，因为每个segment有两个三角形
        int tri_VertexIndexCount = segments * 6;
        int[] tri = new int[tri_VertexIndexCount];
        for (int i = 0, j = 0; i < tri_VertexIndexCount; i += 6, j += 2)
        {
            tri[i] = j;
            tri[i + 1] = j + 1;
            tri[i + 2] = j + 3;
            tri[i + 3] = j + 3;
            tri[i + 4] = j + 2;
            tri[i + 5] = j;
        }

        //根据顶点位置，设置UV纹理坐标
        Vector2[] uv = new Vector2[vertexLen];
        for (int i = 0; i < vertexLen; i++)
        {
            uv[i] = new Vector2(vertex[i].x / radius / 2 + 0.5f, vertex[i].z / radius / 2 + 0.5f);
        }

        mesh.vertices = vertex;
        mesh.triangles = tri;
        mesh.uv = uv;
        mesh.name = "Sphere";
        return mesh;
    }

    private Material CreateMaterial()
    {
        Material material = new Material(Shader.Find("Specular"));
        material.mainTexture = AssetDatabase.LoadAssetAtPath<Texture2D>("Assets/111.png");
        return material;
    }
}