using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace BF
{

    [RequireComponent(typeof(MeshRenderer), typeof(MeshFilter))]
    public class SkillSectorMesh : MonoBehaviour
    {
        public float Radius = 1;          //外半径
        public float InnerRadius = 0;     //内半径
        public float AngleDegree = 360;   //扇形或扇面的角度
        public int Segments = 60;         //分割数

        private MeshFilter meshFilter;

        void Start()
        {
            meshFilter = GetComponent<MeshFilter>();
        }

        Mesh CreateMesh(float radius, float innerradius,float angledegree,int segments)
        {
            int verticesCount = segments * 2 + 2;   // 因为vertices(顶点)的个数与triangles（索引三角形顶点数）必须匹配
            Vector3[] vertices = new Vector3[verticesCount];
            float angleCur =  Mathf.Deg2Rad * (angledegree/2 + 90);
            float angledelta = (Mathf.Deg2Rad * angledegree) / segments;

            for(int i = 0; i < verticesCount; i += 2)
            {
                float cosA = Mathf.Cos(angleCur);
                float sinA = Mathf.Sin(angleCur);
                vertices[i] = new Vector3(radius * cosA, 0, radius * sinA);
                vertices[i + 1] = new Vector3(innerradius * cosA, 0, innerradius * sinA);
                angleCur -= angledelta;
            }

            int triangleCount = segments * 6;
            int[] triangles = new int[triangleCount];
            for(int i = 0, vi = 0; i < triangleCount; i += 6, vi += 2)
            {
                triangles[i] = vi;
                triangles[i + 1] = vi + 3;
                triangles[i + 2] = vi + 1;
                triangles[i + 3] = vi + 2;
                triangles[i + 4] = vi + 3;
                triangles[i + 5] = vi;
            }

            //uv:
            Vector2[] uvs = new Vector2[verticesCount];
            for (int i = 0; i < verticesCount; i++)
            {
                uvs[i] = new Vector2(vertices[i].x / radius / 2 + 0.5f, vertices[i].z / radius / 2 + 0.5f);
            }

            Mesh mesh = new Mesh();
            mesh.vertices = vertices;
            mesh.triangles = triangles;
            mesh.uv = uvs;
            return mesh;
        }

        public void RefreshMesh()
        {
            meshFilter.mesh = CreateMesh(Radius, InnerRadius, AngleDegree, Segments);
        }
    }
}