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

/// <summary>
/// Generate XZ plane
/// </summary>
public class PlaneGenerator : MeshProcessor
{
    public float Width = 1;
    public float Height = 1;

    public int WidthSlices = 0;
    public int HeightSlices = 0;


    public override void Execute(ProceduralMeshData m)
    {
        int widthVertexCount = 2 + WidthSlices;
        int heightVertexCount = 2 + HeightSlices;
        int vertexCount = widthVertexCount*heightVertexCount;

        //generate vertices && normals
        Vector3 offset = new Vector3(-Width / 2, 0, Height / 2);
        m.Vertices = new Vector3[vertexCount];
        m.Normals = new Vector3[vertexCount];

        for (int x = 0; x < widthVertexCount; ++x)
        {
            for (int z = 0; z < heightVertexCount; ++z)
            {
                int id = z*widthVertexCount + x;
                m.Vertices[id]= new Vector3((Width / (widthVertexCount - 1)) * x, 0, (-Height / (heightVertexCount - 1)) * z) + offset;
                m.Normals[id] = Vector3.up;
            }
        }


        //generate indices
        int[] indices = new int[(widthVertexCount - 1) * (heightVertexCount - 1) * 6];
        int indexOffset = 0;
        for (int x = 0; x < widthVertexCount - 1; ++x){
            for (int z = 0; z < heightVertexCount - 1; ++z) {
                indices[indexOffset + 0] = z * widthVertexCount + x;
                indices[indexOffset + 1] = z * widthVertexCount + x + 1;
                indices[indexOffset + 2] = (z + 1) * widthVertexCount + x;
                indices[indexOffset + 3] = indices[indexOffset + 2];
                indices[indexOffset + 4] = indices[indexOffset + 1];
                indices[indexOffset + 5] = (z + 1) * widthVertexCount + x + 1;
                indexOffset += 6;
            }
        }

        m.Indices.Add(indices);

        //generate uvs
        List<Vector4> uvs = new List<Vector4>(vertexCount);
        for (int z = 0; z < heightVertexCount; ++z)
        {
            for (int x = 0; x < widthVertexCount; ++x)
            {
           
                uvs.Add(new Vector4((float)x / (widthVertexCount - 1), (float)z / (heightVertexCount - 1), 0, 0));
            }
        }
        m.Uvs.Add(uvs);
    }
}