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

/// <summary>
/// 多边形 顺时针 先添加中心点 (0,0), 在添加N个顶点就可以了
/// [转] http://www.xshadow.org/index.php/archives/73
/// </summary>

public class UIPolygon : Graphic
{

    public List<Vector2> m_VertexList = new List<Vector2>();  // 顶点坐标列表 数量必须大于2

    private VertexHelper m_VertexHelper;

    public void Refresh()
    {
        if (m_VertexHelper == null)
        {
            Debug.Log("m_VertexHelper == null");
            return;
        }
        m_VertexHelper.Clear();

        List<UIVertex> targetVertexList = new List<UIVertex>();
        int triangleCount = m_VertexList.Count - 1;
        for (int i = 0; i < triangleCount; i++)
        {
            // 组建三角形
            for (int j = 0; j < 3; j++)
            {
                UIVertex vertex = new UIVertex();
                if (j == 2)
                    vertex.position = m_VertexList[0];
                else
                {
                    int vertexIndex = i + j + 1;

                    if (vertexIndex > triangleCount)
                        vertex.position = m_VertexList[1];
                    else
                        vertex.position = m_VertexList[vertexIndex];
                }

     
                vertex.color = color;
                if (j == 2)
                    //vertex.color = new Color(color.r, color.g, color.b, 0);
                vertex.color = new Color(0,0,0, 0);

                targetVertexList.Add(vertex);
            }
        }

        m_VertexHelper.AddUIVertexTriangleStream(targetVertexList);
    }

    protected override void OnPopulateMesh(VertexHelper vh)
    {
        base.OnPopulateMesh(vh);
        m_VertexHelper = vh;

        if (m_VertexList == null)
            return;

        if (m_VertexList.Count < 3)
            return;

        Refresh();
    }
}