创建一个扇形Mesh

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using UnityEngine;using System.Collections;/* ============================================================================== * 功能描述：测试Mesh创建 * 创 建 者：cjunhong * Q    Q  ：327112182 * 创建日期：2014/11/26 11:23:58 * ==============================================================================*/[RequireComponent(typeof(MeshRenderer), typeof(MeshFilter))]public class TestMesh : MonoBehaviour {    public float radius = 2;    public float angleDegree = 100;    public int segments = 10;    public int angleDegreePrecision = 1000;    public int radiusPrecision = 1000;    private MeshFilter meshFilter;    private SectorMeshCreator creator = new SectorMeshCreator();    [ExecuteInEditMode]    private void Awake()    {        meshFilter = GetComponent<MeshFilter>();    }    private void Update()    {        meshFilter.mesh = creator.CreateMesh(radius, angleDegree, segments, angleDegreePrecision, radiusPrecision);    }    void OnDrawGizmos()    {        Gizmos.color = Color.gray;        DrawMesh();    }    void OnDrawGizmosSelected()    {        Gizmos.color = Color.green;        DrawMesh();    }    private void DrawMesh()    {        Mesh mesh = creator.CreateMesh(radius, angleDegree, segments, angleDegreePrecision, radiusPrecision);        int[] tris = mesh.triangles;        for (int i = 0; i < tris.Length; i+=3)        {            Gizmos.DrawLine(convert2World(mesh.vertices[tris[i]]), convert2World(mesh.vertices[tris[i + 1]]));            Gizmos.DrawLine(convert2World(mesh.vertices[tris[i]]), convert2World(mesh.vertices[tris[i + 2]]));            Gizmos.DrawLine(convert2World(mesh.vertices[tris[i+1]]), convert2World(mesh.vertices[tris[i + 2]]));        }    }    private Vector3 convert2World(Vector3 src)    {        return transform.TransformPoint(src);    }    private class SectorMeshCreator    {        private float radius;        private float angleDegree;        private int segments;        private Mesh cacheMesh ;        /// <summary>        /// 创建一个扇形Mesh        /// </summary>        /// <param name="radius">扇形半价</param>        /// <param name="angleDegree">扇形角度</param>        /// <param name="segments">扇形弧线分段数</param>        /// <param name="angleDegreePrecision">扇形角度精度（在满足精度范围内，认为是同个角度）</param>        /// <param name="radiusPrecision">        /// <pre>        /// 扇形半价精度（在满足半价精度范围内，被认为是同个半价）。        /// 比如：半价精度为1000，则：1.001和1.002不被认为是同个半径。因为放大1000倍之后不相等。        /// 如果半价精度设置为100，则1.001和1.002可认为是相等的。        /// </pre>        /// </param>        /// <returns></returns>        public Mesh CreateMesh(float radius, float angleDegree, int segments, int angleDegreePrecision, int radiusPrecision)        {            if (checkDiff(radius, angleDegree, segments, angleDegreePrecision, radiusPrecision))            {                Mesh newMesh = Create(radius, angleDegree, segments);                if (newMesh != null)                {                    cacheMesh = newMesh;                    this.radius = radius;                    this.angleDegree = angleDegree;                    this.segments = segments;                }            }            return cacheMesh;        }        private Mesh Create(float radius, float angleDegree, int segments)        {            if (segments == 0)            {                segments = 1;#if UNITY_EDITOR                Debug.Log("segments must be larger than zero.");#endif            }            Mesh mesh = new Mesh();            Vector3[] vertices = new Vector3[3 + segments - 1];            vertices[0] = new Vector3(0, 0, 0);            float angle = Mathf.Deg2Rad * angleDegree;            float currAngle = angle / 2;            float deltaAngle = angle / segments;            for (int i = 1; i < vertices.Length; i++)            {                vertices[i] = new Vector3(Mathf.Cos(currAngle) * radius, 0, Mathf.Sin(currAngle) * radius);                currAngle -= deltaAngle;            }            int[] triangles = new int[segments * 3];            for (int i = 0, vi = 1; i < triangles.Length; i += 3, vi++)            {                triangles[i] = 0;                triangles[i + 1] = vi;                triangles[i + 2] = vi + 1;            }            mesh.vertices = vertices;            mesh.triangles = triangles;            Vector2[] uvs = new Vector2[vertices.Length];            for (int i = 0; i < uvs.Length; i++)            {                uvs[i] = new Vector2(vertices[i].x, vertices[i].z);            }            mesh.uv = uvs;            return mesh;        }        private bool checkDiff(float radius, float angleDegree, int segments, int angleDegreePrecision, int radiusPrecision)        {            return segments != this.segments || (int)((angleDegree - this.angleDegree) * angleDegreePrecision) != 0 ||                   (int)((radius - this.radius) * radiusPrecision) != 0;        }    }    }
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