HDRP Mask Map Generator

Generator.cs

/**
 * Licence: MIT
 * Author:  Felix Queißner, 2020
 * 
 * Compile with:
 * csc /out:Generator.cs /r:System.Drawing.dll Generator.cs
 *
 * Usage:
 * Execute with a single file argument, this tool will generate a mask map for
 * the Unity HDRP shader set. It assumes that the required files exist with
 * the corresponding file postfixes (_metallic, _ao, _detail, _roughness).
 *
 * The file that is used as an argument is read in, and all channels are replaced
 * by either the default (255) or the corresponding pixel from the map file (if any).
 *
 * The pixel mapping done is the following: 
 * | Parameter   | Channel | Postfixes               |
 * | Metallic    | R       | _metallic               |
 * | AO          | G       | _ao                     |
 * | Detail mask | B       | _detail                 |
 * | Smoothness  | A       | _roughness, _smoothness |
 *
 * This tool will then create a new file "filename_mask.ext" that will replace the original
 * postfix with `_mask` and keep all other settings.
 *
 * Pro Tip for Windows: Put a link to the file into the `shell:sendto`-Folder to allow simpe generation
 * by using `Right Click → Send To → HDRP MaskMap Generator`.
 */

using System;
using System.Drawing;
using System.IO;

class Program
{

  static string[] postfixes = new[]{
    "_metallic",
    "_normal",
    "_albedo",
    "_ao",
    "_detail",
    "_roughness",
    "_height",
  };

  static void PixelMap(Bitmap _out, string fileIn, Func<Color, int, Color> mapper)
  {
    using (var src = new Bitmap(fileIn))
    {
      for (int y = 0; y < src.Height; y++)
      {
        for (int x = 0; x < src.Width; x++)
        {
          var s = src.GetPixel(x, y);
          var d = _out.GetPixel(x, y);
          var c = mapper(d, s.R);
          _out.SetPixel(x, y, c);
        }
      }
    }
  }

  [STAThread]
  static int Main(string[] args)
  {
    if (args.Length != 1)
      return 1;

    var path = Path.GetDirectoryName(args[0]);
    var ext = Path.GetExtension(args[0]);
    var name = Path.GetFileNameWithoutExtension(args[0]);

    int i;
    for (i = 0; i < postfixes.Length; i++)
    {
      if (name.EndsWith(postfixes[i]))
      {
        name = name.Substring(0, name.Length - postfixes[i].Length);
        break;
      }
    }
    if (i == postfixes.Length)
      return 1;

    using (var any = new Bitmap(args[0]))
    {
      using (var g = Graphics.FromImage(any))
        g.Clear(Color.White);

      if (File.Exists(path + "/" + name + "_metallic" + ext))
        PixelMap(any, path + "/" + name + "_metallic" + ext, (rgb, v) => Color.FromArgb(rgb.A, v, rgb.G, rgb.B));

      if (File.Exists(path + "/" + name + "_ao" + ext))
        PixelMap(any, path + "/" + name + "_ao" + ext, (rgb, v) => Color.FromArgb(rgb.A, rgb.R, v, rgb.B));

      if (File.Exists(path + "/" + name + "_detail" + ext))
        PixelMap(any, path + "/" + name + "_detail" + ext, (rgb, v) => Color.FromArgb(rgb.A, rgb.R, rgb.G, v));

      if (File.Exists(path + "/" + name + "_roughness" + ext))
        PixelMap(any, path + "/" + name + "_roughness" + ext, (rgb, v) => Color.FromArgb(255 - v, rgb.R, rgb.G, rgb.B));

      if (File.Exists(path + "/" + name + "_smoothness" + ext))
        PixelMap(any, path + "/" + name + "_smoothness" + ext, (rgb, v) => Color.FromArgb(v, rgb.R, rgb.G, rgb.B));

      any.Save(path + "/" + name + "_mask" + ext);
    }
    return 0;
  }
}