// Creates a Unity Mesh that contains a wavy 2D surface, then animates that surface.
// Based on grid.cs (except now in the X/Z plane), gives each vertex a different height using Sin & Cos.
// Should be attached to a GameObject that already has a MeshFilter component.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class waves : MonoBehaviour {

  public int numRows=10, numCols=10;
  public float minX=-1, maxX=1, minZ=-1, maxZ=1;
  public float height=0.1f;
  private Vector3[] myVerts;

  void Start ()
    {
    int index;
    myVerts = new Vector3[numRows*numCols];
    index = 0;
    for (int j=0; j < numRows; j++)
        for (int i=0; i < numCols; i++)
            {
            float x = Mathf.Lerp(minX,maxX,i/(numCols-1f));
            float z = Mathf.Lerp(minZ,maxZ,j/(numRows-1f));
            float y = Mathf.Sin(x*5f) * Mathf.Cos(z*5f) * height;
            myVerts[index] = new Vector3(x,y,z);
            index++;
            }
    int[] myTris = new int[(numRows-1)*(numCols-1)*2*3];
    index = 0;
    for (int j=0; j < numRows-1; j++)
        for (int i=0; i < numCols-1; i++)
            {
            myTris[index++] = i + j*numCols;
            myTris[index++] = i + (j+1)*numCols;
            myTris[index++] = (i+1) + j*numCols;
            myTris[index++] = i + (j+1)*numCols;
            myTris[index++] = (i+1) + (j+1)*numCols;
            myTris[index++] = (i+1) + j*numCols;
            }
    Mesh myMesh = gameObject.GetComponent<MeshFilter>().mesh;
    myMesh.Clear();
    myMesh.vertices = myVerts;
    myMesh.triangles = myTris;
	myMesh.RecalculateNormals();
    }

  void Update ()
    {
    int index = 0;
    for (int j=0; j < numRows; j++)
        for (int i=0; i < numCols; i++)
            {
            float x = myVerts[index].x;
            float z = myVerts[index].z;
            float y = Mathf.Sin(x*5f+Time.time) * Mathf.Cos(z*5f+Time.time/3f) * height;
            myVerts[index] = new Vector3(x,y,z);
            index++;
            }
    Mesh myMesh = gameObject.GetComponent<MeshFilter>().mesh;
    myMesh.vertices = myVerts;
	myMesh.RecalculateNormals();
   }
}