Further simplify packing algorithm and increase default width

Thief Mission Viewer.csproj

@@ -1,8 +1,8 @@
 <Project Sdk="Godot.NET.Sdk/4.3.0">
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
-    <TargetFramework Condition=" '$(GodotTargetPlatform)' == 'android' ">net7.0</TargetFramework>
-    <TargetFramework Condition=" '$(GodotTargetPlatform)' == 'ios' ">net8.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
+    <!-- <TargetFramework Condition=" '$(GodotTargetPlatform)' == 'android' ">net7.0</TargetFramework>
+    <TargetFramework Condition=" '$(GodotTargetPlatform)' == 'ios' ">net8.0</TargetFramework> -->
     <EnableDynamicLoading>true</EnableDynamicLoading>
     <RootNamespace>ThiefMissionViewer</RootNamespace>
   </PropertyGroup>

project/code/TMV/Mission.cs

@@ -3,7 +3,6 @@ using KeepersCompound.LGS;
 using KeepersCompound.LGS.Database;
 using KeepersCompound.LGS.Database.Chunks;
 using KeepersCompound.TMV.UI;
-using RectpackSharp;
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -261,7 +260,7 @@ public partial class Mission : Node3D
 		var lmHdr = worldRep.DataHeader.LightmapFormat == 2;
 		GD.Print($"HDR Lightmap: {lmHdr}");
 
-		var packingRects = new List<PackingRectangle>();
+		var packingRects = new List<RectPacker.Rect>();
 		var surfaceDataMap = new Dictionary<int, MeshSurfaceData>();
 		var rectDataMap = new Dictionary<int, LightmapRectData>();
 
@@ -288,7 +287,12 @@ public partial class Mission : Node3D
 				rectDataMap.Add(packingRects.Count, lightmapRectData);
 
 				var light = cell.LightList[polyIdx];
-				var rect = new PackingRectangle(0, 0, light.Width, light.Height, packingRects.Count);
+				var rect = new RectPacker.Rect
+				{
+					Width = light.Width,
+					Height = light.Height,
+					Id = packingRects.Count,
+				};
 				packingRects.Add(rect);
 
 				cellIdxOffset += cell.Polys[polyIdx].VertexCount;
@@ -355,16 +359,15 @@ public partial class Mission : Node3D
 
 	private static Texture2DArray BuildLightmapTexture(
 		WorldRep.Cell[] cells,
-		PackingRectangle[] packingRects,
+		RectPacker.Rect[] packingRects,
 		Dictionary<int, LightmapRectData> rectDataMap,
 		Dictionary<int, MeshSurfaceData> surfaceDataMap)
 	{
 		var bounds = Timing.TimeStage("RectPack", () =>
 		{
-			RectanglePacker.Pack(packingRects, out var bounds, PackingHints.FindBest, 0);
-			return bounds;
+			return RectPacker.Pack(packingRects);
 		});
-		GD.Print($"Creating lightmap with bounds: ({bounds.Width}, {bounds.Height})");
+		GD.Print($"Packed {packingRects.Length} rects in ({bounds.Width}, {bounds.Height})");
 
 		var lightmapFormat = Image.Format.Rgba8;
 		var lmLayerCount = 33; // TODO: Use LightmapLayers
@@ -413,6 +416,7 @@ public partial class Mission : Node3D
 				return new Vector2(u, v);
 			});
 		}
+		lmImages[0].SavePng("user://lm.png");
 
 		var lightmapTexture = new Texture2DArray();
 		lightmapTexture.CreateFromImages(lmImages);

project/code/TMV/RectPacker.cs

@@ -0,0 +1,60 @@
+using System;
+
+namespace KeepersCompound.TMV;
+
+public static class RectPacker
+{
+    public struct Rect
+    {
+        public int Id;
+        public ushort X;
+        public ushort Y;
+        public ushort Width;
+        public ushort Height;
+    }
+
+    public static Rect Pack(Rect[] rectangles, ushort width = 2048, ushort minHeight = 512)
+    {
+        ArgumentNullException.ThrowIfNull(rectangles);
+        ArgumentOutOfRangeException.ThrowIfZero(width);
+        ArgumentOutOfRangeException.ThrowIfZero(minHeight);
+
+        var bounds = new Rect
+        {
+            Width = width,
+            Height = minHeight
+        };
+        if (rectangles.Length == 0)
+        {
+            return bounds;
+        }
+
+        Array.Sort(rectangles, (a, b) => b.Height.CompareTo(a.Height));
+
+        // Naively try to pack into the row, wrapping when we reach the end
+        // and expanding the bounds when needed
+        ushort rowMaxH = rectangles[0].Height;
+        ushort x = 0;
+        ushort y = 0;
+        var rectCount = rectangles.Length;
+        for (var i = 0; i < rectCount; i++)
+        {
+            var rect = rectangles[i];
+            if (x + rect.Width > width)
+            {
+                x = 0;
+                y += rowMaxH;
+                rowMaxH = rect.Height;
+            }
+
+            rect.X = x;
+            rect.Y = y;
+            rectangles[i] = rect;
+
+            x += rect.Width;
+        }
+
+        bounds.Height = (ushort)(y + rowMaxH);
+        return bounds;
+    }
+}