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

public class Trigonometric : MonoBehaviour
{
    Mesh mesh;

    public int minX;
    public int maxX;

    public TriType triType;
    public float a;
    public float b;
    public float factor;
    public enum TriType
    {
        Sin,
        Cos,
        Tan
    }
    // Start is called before the first frame update
    void Start()
    {
        mesh = new Mesh
        {
            name = "Trigonometric"
        };
    }

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

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

        float step = 0.01f;
        Vector3[] vectors = new Vector3[100 * (maxX - minX) + 1];
        int k = 0;
        for (float i = minX; i <= maxX; i = i + step)
        {
            float y = a * i + b;
            switch (triType)
            {
                case TriType.Sin:
                    y = Mathf.Sin(y);
                    break;
                case TriType.Cos:
                    y = Mathf.Cos(y);
                    break;
                case TriType.Tan:
                    y = Mathf.Tan(y);
                    break;
                default:
                    break;
            }
            y *= factor;
            vectors[k] = new Vector3(i, y, 0);
            k++;
        }
        switch (triType)
        {
            case TriType.Sin:
                vectors[100 * (maxX - minX)] = new Vector3(maxX, Mathf.Sin(a * maxX + b) * factor, 0);
                break;
            case TriType.Cos:
                vectors[100 * (maxX - minX)] = new Vector3(maxX, Mathf.Cos(a * maxX + b) * factor, 0);
                break;
            case TriType.Tan:
                vectors[100 * (maxX - minX)] = new Vector3(maxX, Mathf.Tan(a * maxX + b) * factor, 0);
                break;
            default:
                break;
        }
        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;
    }
    public void DrawTrigonometric3D()
    {
        mesh.Clear();

        float step = 0.01f;
        Vector3[] vectors = new Vector3[200 * (maxX - minX) + 2];
        int k = 0;
        for (float i = minX; i <= maxX; i = i + step)
        {
            float y = a * i + b;
            switch (triType)
            {
                case TriType.Sin:
                    y = Mathf.Sin(y);
                    break;
                case TriType.Cos:
                    y = Mathf.Cos(y);
                    break;
                case TriType.Tan:
                    y = Mathf.Tan(y);
                    break;
                default:
                    break;
            }
            y *= factor;
            vectors[k] = new Vector3(i, y, -5);
            k++;
            vectors[k] = new Vector3(i, y, 5);
            k++;
        }
        switch (triType)
        {
            case TriType.Sin:
                vectors[200 * (maxX - minX)] = new Vector3(maxX, Mathf.Sin(a * maxX + b) * factor, -5);
                vectors[200 * (maxX - minX) + 1] = new Vector3(maxX, Mathf.Sin(a * maxX + b) * factor, 5);
                break;
            case TriType.Cos:
                vectors[200 * (maxX - minX)] = new Vector3(maxX, Mathf.Cos(a * maxX + b) * factor, -5);
                vectors[200 * (maxX - minX) + 1] = new Vector3(maxX, Mathf.Cos(a * maxX + b) * factor, 5);
                break;
            case TriType.Tan:
                vectors[200 * (maxX - minX)] = new Vector3(maxX, Mathf.Tan(a * maxX + b) * factor, -5);
                vectors[200 * (maxX - minX) + 1] = new Vector3(maxX, Mathf.Tan(a * maxX + b) * factor, 5);
                break;
            default:
                break;
        }
        mesh.vertices = vectors;

        Vector2[] uvs = new Vector2[vectors.Length];
        for (int i = 0; i < uvs.Length; i++)
        {
            uvs[i] = new Vector2(0, vectors[i].y / 100);
        }
        mesh.uv = uvs;

        int[] triangle = new int[100 * (maxX - minX) * 6];
        for (int i = 0; i < 100 * (maxX - minX); ++i)
        {
            if(vectors[2 * i].y * vectors[2 * i + 2].y >= 0)
            {
                triangle[6 * i] = 2 * i;
                triangle[6 * i + 1] = 2 * i + 1;
                triangle[6 * i + 2] = 2 * i + 2;
                triangle[6 * i + 3] = 2 * i + 1;
                triangle[6 * i + 4] = 2 * i + 3;
                triangle[6 * i + 5] = 2 * i + 2;
            }
            else
            {
                triangle[6 * i] = 2 * i;
                triangle[6 * i + 1] = 2 * i + 1;
                triangle[6 * i + 2] = 2 * i;
                triangle[6 * i + 3] = 2 * i + 3;
                triangle[6 * i + 4] = 2 * i + 3;
                triangle[6 * i + 5] = 2 * i + 2;
            }
        }
        mesh.SetIndices(triangle, MeshTopology.Triangles, 0);

        GetComponent<MeshFilter>().mesh = mesh;
    }
    public void MeshClear()
    {
        mesh.Clear();
        GetComponent<MeshFilter>().mesh = mesh;
    }
}