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

[AddComponentMenu("UI/Effects/Nicer Outline", 15)]
public class NicerOutline : BaseMeshEffect
{
    [SerializeField] private Color effectColor = new Color(0f, 0f, 0f, 1f);
    [SerializeField] private float effectDistanceX = 2f;
    [SerializeField] private float effectDistanceY = 2f;
   [Range(4,12)] [SerializeField] private int samplingRate = 10;
    
    private static readonly List<UIVertex> vertexList = new List<UIVertex>();
    private static readonly List<UIVertex> tempVertexList = new List<UIVertex>();

    public override void ModifyMesh(VertexHelper vh)
    {
        if (!IsActive()) return;

        vertexList.Clear();
        tempVertexList.Clear();
        vh.GetUIVertexStream(vertexList);

        int count = vertexList.Count;
        for (int j = 0; j < samplingRate; j++)
        {
            for (int i = 0; i < count; i++)
            {
                UIVertex v = vertexList[i];
                float angle = j * Mathf.PI * 2f / samplingRate;
                Vector2 offset = new Vector2(Mathf.Cos(angle) * effectDistanceX, Mathf.Sin(angle) * effectDistanceY);
                UIVertex outlinedVert = new UIVertex();
                outlinedVert.position = v.position + (Vector3)offset;
                outlinedVert.normal = v.normal;
                outlinedVert.tangent = v.tangent;
                outlinedVert.uv0 = v.uv0;
                outlinedVert.uv1 = v.uv1;
                outlinedVert.color = effectColor;
                tempVertexList.Add(outlinedVert);
            }
        }
        tempVertexList.AddRange(vertexList);
        vh.Clear();
        vh.AddUIVertexTriangleStream(tempVertexList);
    }

}