TiledTerrain/Assets/Tile Terrain/Runtime/TerrainAsset.cs

using System;
using System.Buffers;
using UnityEditor;
using UnityEngine;
using UnityEngine.Experimental.Rendering;

namespace BitGames.Terrain
{
  public class TerrainAsset : ScriptableObject
  {
    public int Size;
    public BiomesAsset BiomesAsset;
    public Texture2D ControlTexture;
    public Texture2D ShadowTexture;
    public Color ShadowColor = new(0.2f, 0.2f, 0.2f, 0.5f);

    public static TerrainAsset Create(string path, int size)
    {
      var asset = CreateInstance<TerrainAsset>();

      asset.Size = size;

      var controlTexture = new Texture2D(size, size, TextureFormat.RG16, false);
      controlTexture.name = "Control Texture";
      controlTexture.filterMode = FilterMode.Point;

      var shadowTexture = new Texture2D(size, size, TextureFormat.R8, true);
      shadowTexture.name = "Shadow Texture";
      controlTexture.filterMode = FilterMode.Bilinear;

      var colorBuffer = ArrayPool<Color32>.Shared.Rent(size * size);
      try
      {
        Array.Fill(colorBuffer, GetControlMapDefault());
        controlTexture.SetPixels32(0, 0, size, size, colorBuffer);
        controlTexture.Apply();

        Array.Fill(colorBuffer, GetShadowMapDefault());
        shadowTexture.SetPixels32(0, 0, size, size, colorBuffer);
        shadowTexture.Apply();
      }
      finally
      {
        ArrayPool<Color32>.Shared.Return(colorBuffer);
      }

      asset.ControlTexture = controlTexture;
      asset.ShadowTexture = shadowTexture;

      AssetDatabase.CreateAsset(asset, path);
      AssetDatabase.AddObjectToAsset(asset.ControlTexture, asset);
      AssetDatabase.AddObjectToAsset(asset.ShadowTexture, asset);
      AssetDatabase.ImportAsset(path);

      return asset;
    }

    private static Color32 GetControlMapDefault()
    {
      return new Color32(0, (byte)ControlFlags.DEFAULT, 0, 0);
    }

    private static Color32 GetShadowMapDefault()
    {
      return Color.black;
    }
  }
}