From f6ef623bb4fa6dd499ac216173abb6b61abc4857 Mon Sep 17 00:00:00 2001
From: Jarrod Doyle <thejarroddoyle@gmail.com>
Date: Wed, 28 Aug 2024 22:03:48 +0100
Subject: [PATCH] Simplify packing by reversing sort and growing in only 1
 direction

---
 project/code/TMV/Mission.cs    |  4 +-
 project/code/TMV/RectPacker.cs | 73 +++++-----------------------------
 2 files changed, 10 insertions(+), 67 deletions(-)

diff --git a/project/code/TMV/Mission.cs b/project/code/TMV/Mission.cs
index 7b1e10e..435e3ec 100644
--- a/project/code/TMV/Mission.cs
+++ b/project/code/TMV/Mission.cs
@@ -365,10 +365,8 @@ public partial class Mission : Node3D
 	{
 		var bounds = Timing.TimeStage("RectPack", () =>
 		{
-			var bounds = RectPacker.Pack(packingRects);
-			return bounds;
+			return RectPacker.Pack(packingRects);
 		});
-		bounds = RectPacker.TightBounds(packingRects);
 		GD.Print($"Packed {packingRects.Length} rects in ({bounds.Width}, {bounds.Height})");
 
 		var lightmapFormat = Image.Format.Rgba8;
diff --git a/project/code/TMV/RectPacker.cs b/project/code/TMV/RectPacker.cs
index d7ddef7..250a5c2 100644
--- a/project/code/TMV/RectPacker.cs
+++ b/project/code/TMV/RectPacker.cs
@@ -13,21 +13,15 @@ public static class RectPacker
         public ushort Height;
     }
 
-    enum ExpandDir
-    {
-        X,
-        Y,
-    }
-
-    public static Rect Pack(Rect[] rectangles, ushort minWidth = 512, ushort minHeight = 512)
+    public static Rect Pack(Rect[] rectangles, ushort width = 1024, ushort minHeight = 512)
     {
         ArgumentNullException.ThrowIfNull(rectangles);
-        ArgumentOutOfRangeException.ThrowIfZero(minWidth);
+        ArgumentOutOfRangeException.ThrowIfZero(width);
         ArgumentOutOfRangeException.ThrowIfZero(minHeight);
 
         var bounds = new Rect
         {
-            Width = minWidth,
+            Width = width,
             Height = minHeight
         };
         if (rectangles.Length == 0)
@@ -35,51 +29,25 @@ public static class RectPacker
             return bounds;
         }
 
-        Array.Sort(rectangles, (a, b) => a.Height.CompareTo(b.Height));
+        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 rowStartX = 0;
-        ushort rowMaxH = 0;
+        ushort rowMaxH = rectangles[0].Height;
         ushort x = 0;
         ushort y = 0;
-        var expandDir = ExpandDir.Y;
         var rectCount = rectangles.Length;
         for (var i = 0; i < rectCount; i++)
         {
             var rect = rectangles[i];
-            if (rect.Width == 0 || rect.Height == 0)
-            {
-                throw new ArgumentOutOfRangeException(nameof(rectangles), rectangles, $"{nameof(rectangles)} contains rect with width or height 0.");
-            }
-
-            // uh oh we've hit the edge, wrap to next row
             if (x + rect.Width > bounds.Width)
             {
-                // we just loop to next row
-                x = rowStartX;
+                x = 0;
                 y += rowMaxH;
-                rowMaxH = 0;
-            }
-
-            // uh oh we've hit the edge, expand
-            if (y + rect.Height > bounds.Height)
-            {
-                if (expandDir == ExpandDir.X)
+                rowMaxH = rect.Height;
+                if (y + rowMaxH > bounds.Height)
                 {
-                    // We can expand to the right
-                    x = bounds.Width;
-                    rowStartX = bounds.Width;
-                    y = 0;
-                    rowMaxH = 0;
-                    bounds.Width *= 2;
-                    expandDir = ExpandDir.Y;
-                }
-                else if (expandDir == ExpandDir.Y)
-                {
-                    rowStartX = 0;
                     bounds.Height *= 2;
-                    expandDir = ExpandDir.X;
                 }
             }
 
@@ -88,32 +56,9 @@ public static class RectPacker
             rectangles[i] = rect;
 
             x += rect.Width;
-            if (rect.Height > rowMaxH)
-            {
-                rowMaxH = rect.Height;
-            }
         }
 
-        return bounds;
-    }
-
-    public static Rect TightBounds(Rect[] rectangles)
-    {
-        var bounds = new Rect();
-        foreach (var rect in rectangles)
-        {
-            var w = rect.X + rect.Width;
-            if (w > bounds.Width)
-            {
-                bounds.Width = (ushort)w;
-            }
-
-            var h = rect.Y + rect.Height;
-            if (h > bounds.Height)
-            {
-                bounds.Height = (ushort)h;
-            }
-        }
+        bounds.Height = (ushort)(y + rowMaxH);
         return bounds;
     }
 }