thief-mission-viewer/project/code/TMV/RectPacker.cs

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;
    }
}