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

public class InverseTri : MonoBehaviour
{
    Mesh mesh;

    public int minX;
    public int maxX;
    public enum InverseTriTpye
    {
        Arcsin,
        Arccos,
        Arctan
    }

    public InverseTriTpye inverseTriTpye;
    // Start is called before the first frame update
    void Start()
    {
        mesh = new Mesh
        {
            name = "InverseTri"
        };
    }

    // Update is called once per frame
    void Update()
    {
        
    }

    public void DrawInverseTri()
    {
        mesh.Clear();

        if(inverseTriTpye != InverseTriTpye.Arctan)
        {
            float step = 0.01f;
            Vector3[] vectors = new Vector3[100 * 2 + 1];
            int k = 0;
            for (float i = -1; i <= 1; i = i + step)
            {
                float y = i;
                switch (inverseTriTpye)
                {
                    case InverseTriTpye.Arcsin:
                        y = Mathf.Asin(y);
                        break;
                    case InverseTriTpye.Arccos:
                        y = Mathf.Acos(y);
                        break;
                    default:
                        break;
                }
                vectors[k] = new Vector3(i, y, 0);
                k++;
            }
            switch (inverseTriTpye)
            {
                case InverseTriTpye.Arcsin:
                    vectors[100 * 2] = new Vector3(1, Mathf.Asin(1), 0);
                    break;
                case InverseTriTpye.Arccos:
                    vectors[100 * 2] = new Vector3(1, Mathf.Acos(1), 0);
                    break;
                default:
                    break;
            }
            mesh.vertices = vectors;

            int[] triangle = new int[100 * 2 * 2];
            for (int i = 0; i < vectors.Length - 1; ++i)
            {
                if (vectors[i].y * vectors[i + 1].y >= 0)
                {
                    triangle[2 * i] = i;
                    triangle[2 * i + 1] = i + 1;
                }
                else
                {
                    triangle[2 * i] = i;
                    triangle[2 * i + 1] = i;
                }
            }
            mesh.SetIndices(triangle, MeshTopology.Lines, 0);
        }
        else
        {
            float step = 0.01f;
            Vector3[] vectors = new Vector3[100 * (maxX - minX) + 1];
            int k = 0;
            for (float i = -1; i <= 1; i = i + step)
            {
                float y = i;
                y = Mathf.Atan(y);
                vectors[k] = new Vector3(i, y, 0);
                k++;
            }
            vectors[100 * (maxX - minX)] = new Vector3(maxX, Mathf.Atan(maxX), 0);
            mesh.vertices = vectors;

            int[] triangle = new int[100 * (maxX - minX) * 2];
            for (int i = 0; i < vectors.Length - 1; ++i)
            {
                if (vectors[i].y * vectors[i + 1].y >= 0)
                {
                    triangle[2 * i] = i;
                    triangle[2 * i + 1] = i + 1;
                }
                else
                {
                    triangle[2 * i] = i;
                    triangle[2 * i + 1] = i;
                }
            }
            mesh.SetIndices(triangle, MeshTopology.Lines, 0);
        }

        GetComponent<MeshFilter>().mesh = mesh;
    }
}