writing out layers

src/GMSprite.cs

@@ -21,10 +21,16 @@ namespace Palettizer
 		public GMSpriteCompositeImage CompositeImage { get; set; }
 	}
 
+	public struct GMSpriteLayer
+	{
+		public string Name { get; set; } // this is actually a GUID lol
+    }
+
 	public struct GMSprite
 	{
 		public GMTextureGroupID TextureGroupID { get; set; }
 		public GMSpriteFrame[] Frames { get; set; }
+		public GMSpriteLayer[] Layers { get; set; }
         public string ResourceType { get; set; }
 		public string Name { get; set; }
 	}

src/Palette.cs

@@ -27,9 +27,9 @@ namespace Palettizer
 			if (GrayscaleToColorMap.ContainsKey((byte)average))
 			{
                 var increment = 1;
-                for (var i = 0; i < 256 - GrayscaleCount; i += 1)
+                for (var i = 0; i < 256; i += 1)
 				{
-                    average += increment;
+                    average = (average + increment) % 256;
 
 					if (!GrayscaleToColorMap.ContainsKey((byte)average))
 					{
@@ -38,7 +38,6 @@ namespace Palettizer
 
                     increment = ((increment > 0) ? (increment + 1) : (increment - 1)) * -1; // up by 1, down by 2, up by 3, etc
                 }
-
             }
 
             GrayscaleToColorMap.Add((byte)average, color);

src/Program.cs

@@ -46,10 +46,6 @@ namespace Palettizer
 
             console.Out.Write("Parsing: " + gmProject.Name + "\n");
 
-            if (Directory.Exists("output"))
-            {
-                Directory.Delete("output", true);
-            }
             var outputDir = Directory.CreateDirectory("output");
 
 			var palette = new Palette();
@@ -75,8 +71,9 @@ namespace Palettizer
 					{
 						console.Out.Write(sprite.Name + "\n");
 
-						foreach (var spriteFrame in sprite.Frames)
+                        for (var i = 0; i < sprite.Frames.Length; i += 1)
 						{
+                            var spriteFrame = sprite.Frames[i];
                             ImageResult image;
 							byte[] grayscaleImage;
 
@@ -98,6 +95,13 @@ namespace Palettizer
 							{
 								writer.WritePng(grayscaleImage, image.Width, image.Height, StbImageWriteSharp.ColorComponents.RedGreenBlueAlpha, stream);
 							}
+
+							// Now write out the layer
+							// There's just 1 always because nobody uses GM's shit ass sprite editor
+							var layerSpriteWriteDir = Path.Combine(spriteWriteDir, "layers", sprite.Frames[i].CompositeImage.FrameID.Name);
+							Directory.CreateDirectory(layerSpriteWriteDir);
+							var layerSpriteWritePath = Path.Combine(layerSpriteWriteDir, sprite.Layers[0].Name + ".png");
+                            File.Copy(spriteWritePath, layerSpriteWritePath);
 						}
                     }
 				}
@@ -136,6 +140,7 @@ namespace Palettizer
                         }
                     }
 
+					// build the alternate rows
                     for (var j = 1; j < paletteImage.Width; j += 1)
                     {
                         var colorPalette = new Color[256];