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

[RequireComponent(typeof(MeshFilter))]
public class AdvancedMesh : MonoBehaviour

{
    Mesh mesh;

    Vector3[] vertices;
    int[] triangles;

    [SerializeField] public int xSize = 200;
    [SerializeField] public int ySize = 200;

    void Start()
    {
        mesh = new Mesh();
        GetComponent<MeshFilter>().mesh = mesh;
        CreateShape();
        UpdateMesh();
    }

    void CreateShape()
    {
        vertices = new Vector3[(xSize + 1) * (ySize + 1)];

        for (int i = 0, y = 0; y <= ySize; y++)
        {
            for (int x = 0; x <= xSize; x++)
            {
                vertices[i] = new Vector3(x, y, 0);
                i++;
            }
        }


        triangles = new int[xSize * ySize * 6];

        int vert = 0;
        int tris = 0;
        for (int y = 0; y < ySize; y++)
        {
            for (int x = 0; x < xSize; x++)
            {
                triangles[tris + 0] = vert + 0;
                triangles[tris + 1] = vert + xSize + 1;
                triangles[tris + 2] = vert + 1;
                triangles[tris + 3] = vert + 1;
                triangles[tris + 4] = vert + xSize + 1;
                triangles[tris + 5] = vert + xSize + 2;

                vert++;
                tris += 6;
            }
            vert++;
        }
    }
    private void UpdateMesh()
    {
        mesh.Clear();

        mesh.vertices = vertices;
        mesh.triangles = triangles;

        mesh.RecalculateNormals();
    }

    private void OnDrawGizmos()
    {
        if (vertices == null)
            return;

        for (int i = 0; i < vertices.Length; i++)
        {
            Gizmos.DrawSphere(vertices[i], .1f);
        }
    }
}