Support HasShadows flag in BuildingComponentsViewModel rendering

Gui/ViewModels/Graphics/ImageTableViewModel.cs

@@ -5,6 +5,7 @@
 using Common.Logging;
 using Definitions.ObjectModels;
 using Definitions.ObjectModels.Graphics;
+using Definitions.ObjectModels.Objects.Building;
 using Definitions.ObjectModels.Objects.Common;
 using Gui.ViewModels.LocoTypes.Objects.Building;
 using ReactiveUI;
@@ -94,7 +95,7 @@ public class ImageTableViewModel : ReactiveObject, IExtraContentViewModel
 
 	ImageTable Model { get; init; }
 
-	public ImageTableViewModel(ImageTable imageTable, ILogger logger, BuildingComponents? buildingComponents = null)
+	public ImageTableViewModel(ImageTable imageTable, ILogger logger, BuildingComponents? buildingComponents = null, BuildingObjectFlags? buildingFlags = null)
 	{
 		ArgumentNullException.ThrowIfNull(imageTable);
 
@@ -116,7 +117,7 @@ public ImageTableViewModel(ImageTable imageTable, ILogger logger, BuildingCompon
 		// building components
 		if (buildingComponents != null)
 		{
-			BuildingComponents = new(buildingComponents, imageTable);
+			BuildingComponents = new(buildingComponents, imageTable, buildingFlags);
 		}
 
 		_ = this.WhenAnyValue(o => o.SelectedPrimarySwatch).Skip(1)

Gui/ViewModels/LocoTypes/ObjectEditorViewModel.cs

@@ -6,6 +6,7 @@
 using Dat.Data;
 using Dat.FileParsing;
 using Definitions.ObjectModels;
+using Definitions.ObjectModels.Objects.Building;
 using Definitions.ObjectModels.Objects.Common;
 using Definitions.ObjectModels.Objects.Sound;
 using Definitions.ObjectModels.Types;
@@ -264,7 +265,8 @@ public override void Load()
 					else
 					{
 						var bc = CurrentObject.LocoObject.ObjectType == ObjectType.Building ? (CurrentObject.LocoObject.Object as IHasBuildingComponents)?.BuildingComponents : null;
-						ExtraContentViewModel = new ImageTableViewModel(CurrentObject.LocoObject.ImageTable, Model.Logger, bc);
+						var buildingFlags = CurrentObject.LocoObject.ObjectType == ObjectType.Building ? (CurrentObject.LocoObject.Object as BuildingObject)?.Flags : null;
+						ExtraContentViewModel = new ImageTableViewModel(CurrentObject.LocoObject.ImageTable, Model.Logger, bc, buildingFlags);
 					}
 				}
 			}

Gui/ViewModels/LocoTypes/Objects/Building/BuildingComponentsViewModel.cs

@@ -42,6 +42,8 @@ public class BuildingComponentsViewModel : ReactiveObject
 
 	protected ImageTable ImageTable { get; set; }
 
+	protected BuildingObjectFlags? BuildingFlags { get; set; }
+
 	public BuildingComponentsViewModel()
 	{
 		_ = this.WhenAnyValue(x => x.BuildingVariations)
@@ -53,12 +55,13 @@ public BuildingComponentsViewModel()
 		_ = MessageBus.Current.Listen<BuildingComponents>().Subscribe(UpdateBuildingComponents);
 	}
 
-	public BuildingComponentsViewModel(BuildingComponents buildingComponents, ImageTable imageTable) : this()
+	public BuildingComponentsViewModel(BuildingComponents buildingComponents, ImageTable imageTable, BuildingObjectFlags? buildingFlags = null) : this()
 	{
 		ArgumentNullException.ThrowIfNull(buildingComponents);
 		ArgumentNullException.ThrowIfNull(imageTable);
 
 		ImageTable = imageTable;
+		BuildingFlags = buildingFlags;
 		UpdateBuildingComponents(buildingComponents);
 	}
 
@@ -78,13 +81,19 @@ void UpdateBuildingComponents(BuildingComponents buildingComponents)
 
 	protected void RecomputeBuildingVariationViewModels(List<List<uint8_t>> buildingVariations, List<byte> buildingHeights)
 	{
+		const int minPartsForShadowReordering = 2;
+		const int shadowPartIndex = 1;
+		const int basePartIndex = 0;
+
 		var layers = ImageTable.Groups.ConvertAll(x => x.GraphicsElements);
 
 		BuildingVariationViewModels.Clear();
 
 		MaxWidth = layers.Max(x => x.Max(y => y.Width)) + 16;
 		MaxHeight = (layers.Max(x => x.Max(y => y.Height)) * buildingHeights.Count) + buildingHeights.Sum(x => x) + buildingVariations.Max(x => x.Count) * (VerticalLayerSpacing * 2);
 
+		var hasShadows = BuildingFlags?.HasFlag(BuildingObjectFlags.HasShadows) ?? false;
+
 		var x = 0;
 		foreach (var variation in buildingVariations)
 		{
@@ -102,7 +111,20 @@ protected void RecomputeBuildingVariationViewModels(List<List<uint8_t>> building
 				};
 
 				var cumulativeOffset = 0;
-				foreach (var variationItem in variation)
+
+				// When HasShadows flag is set, the first 4 images (part 0) are the base layer
+				// and the second 4 images (part 1) are the shadows.
+				// Shadows should be rendered first (below/behind the base layer).
+				// Example: variation [0, 1, 2] becomes [1, 0, 2] - swap first two parts, keep rest
+				var reorderedVariation = variation;
+				if (hasShadows && variation.Count >= minPartsForShadowReordering)
+				{
+					// Reorder so shadows (part 1) come before base (part 0)
+					// Skip(2) skips the first 2 parts we're explicitly including, avoiding duplication
+					reorderedVariation = [variation[shadowPartIndex], variation[basePartIndex], .. variation.Skip(minPartsForShadowReordering)];
+				}
+
+				foreach (var variationItem in reorderedVariation)
 				{
 					if (layers.Count > variationItem)
 					{