mapgrid1.cs

using System.Collections;
using UnityEngine;

public class mapgrid1 : MonoBehaviour
{
    void Awake()
    {
        MeshFilter meshFilter = gameObject.GetComponent<MeshFilter>();
        Mesh mesh = new Mesh();

        int width = 128;
        int height = 128;

        mesh.vertices = new Vector3[4]
        {
            new Vector3(0, 0, 0),
            new Vector3(width, 0, 0),
            new Vector3(0, height, 0),
            new Vector3(width, height, 0)
        };

        mesh.triangles = new int[6]
        {
            0, 2, 1,    // lower left triangle
            2, 3, 1     // upper right triangle
        };

        mesh.normals = new Vector3[4]
        {
            -Vector3.forward,
            -Vector3.forward,
            -Vector3.forward,
            -Vector3.forward
        };

        mesh.uv = new Vector2[4]
        {
            new Vector2(0, 0),
            new Vector2(1, 0),
            new Vector2(0, 1),
            new Vector2(1, 1)
        };

        meshFilter.mesh = mesh;

        MeshRenderer meshRenderer = gameObject.GetComponent<MeshRenderer>();
        meshRenderer.material = new Material(Shader.Find("Custom/gridshader2"));
        meshRenderer.material.color = new Color(.0f, .1176469f, 1.0f, .866f);
    }
}