[Unity3D] 5.0 图集合并扩展工具，用于解决UGUI与AssetBundle打包造成资源包过大的问题

[Unity3D] 5.0 图集合并扩展工具，用于解决UGUI与AssetBundle打包造成资源包过大的问题

2017年07月05日 15:57:44

阅读数：1494

http://www.cppblog.com/shly/archive/2015/12/09/212443.html

[Unity3D] 5.0 图集合并扩展工具，用于解决UGUI与AssetBundle打包造成资源包过大的问题

UGUI Image已Sprite为主，而简单的合并图集可以使用自带的SpritePacker。
而当在使用AssetBundle的时候情况有些不同，会造成每个AB都会引入完整的Sprite图集，显然就增加了AB的大小，重复资源。
为了解决这个问题我们可以手动合并图集，那么方案也有多种，这里我们可以编辑器自带的API来实现一个小的图集合并工具。

 private static bool CombineSpritesHelper(string path, string dpath, string name, int padding)
    {
        string[] paths = AssetDatabase.FindAssets("t:sprite", new string[] { path });
        List<Sprite> spriteList = new List<Sprite>();
        List<Texture2D> texList = new List<Texture2D>();

        foreach (var o in paths)
        {
            Sprite s = AssetDatabase.LoadAssetAtPath(AssetDatabase.GUIDToAssetPath(o), typeof(Sprite)) as Sprite;
            if (null != s)
            {
                spriteList.Add(s);
                texList.Add(s.texture);
            }
        }

        if (texList.Count > 0)
        {
            Texture2D tex = new Texture2D(1024, 1024, TextureFormat.ARGB32, true);
            Rect[] uvs = UITexturePacker.PackTextures(tex, texList.ToArray(), 4, 4, padding, 1024);
            if (null == uvs)
            {
                EditorUtility.DisplayDialog(path, "图集超过1024，需要分组成多张图集", "点击退出");
                Object.DestroyImmediate(tex);
                tex = null;
                return false;
            }
            else
            {
                List<SpriteMetaData> metaList = new List<SpriteMetaData>();
                for (int i = 0; i < uvs.Length; ++i)
                {
                    SpriteMetaData data = new SpriteMetaData();
                    data.alignment = (int)SpriteAlignment.Center;
                    data.border = spriteList[i].border;
                    data.name = spriteList[i].name;
                    data.pivot = spriteList[i].pivot;
                    data.rect = new Rect(uvs[i].x * tex.width, uvs[i].y * tex.height, uvs[i].width * tex.width, uvs[i].height * tex.height);
                    metaList.Add(data);
                }

                //string dpath = path.Substring(0, path.Length - obj.name.Length) + "SpriteSet";
                if (!System.IO.Directory.Exists(dpath))
                {
                    System.IO.Directory.CreateDirectory(dpath);
                }

                string file = dpath + "/" + name + ".png";
                if (System.IO.File.Exists(file))
                {
                    System.IO.File.Delete(file);
                }
                System.IO.File.WriteAllBytes(file, tex.EncodeToPNG());

                AssetDatabase.ImportAsset(file, ImportAssetOptions.ForceUpdate);
                TextureImporter importer = AssetImporter.GetAtPath(file) as TextureImporter;
                importer.spritesheet = metaList.ToArray();
                importer.spriteImportMode = SpriteImportMode.Multiple;
                importer.textureType = TextureImporterType.Sprite;
                importer.textureFormat = TextureImporterFormat.ARGB32;
                importer.mipmapEnabled = true;
                importer.mipmapFilter = TextureImporterMipFilter.BoxFilter;
                importer.assetBundleName = "ui_image/" + name.ToLower();
                AssetDatabase.ImportAsset(file);
                AssetDatabase.Refresh();
            }
        }
        return true;
    }

    [MenuItem("Tool/Combine Sprites")]
    [MenuItem("Assets/Tool/Combine Sprites")]
    public static void CombineSprites()
    {
        EditorUtility.DisplayProgressBar("Combine Sprites", "Initializing ", 0);
        try
        {
            Object obj = Selection.activeObject;
            string path = AssetDatabase.GetAssetPath(obj.GetInstanceID());
            string dpath = path.Substring(0, path.Length - obj.name.Length) + "SpriteSet";

            if (System.IO.Directory.Exists(path))
            {
                string[] directories = System.IO.Directory.GetDirectories(path);
                int count = 0;
                if (directories.Length > 0)
                {
                    foreach (var directory in directories)
                    {
                        count++;
                        EditorUtility.DisplayProgressBar("Combine Sprites", string.Format("combing {0}", count), (float)(count) / (directories.Length));
                        if (!CombineSpritesHelper(directory, dpath, string.Concat(obj.name, "_", count.ToString()), 1))
                        {
                            break;
                        }
                    }
                }
                else
                {
                    EditorUtility.DisplayProgressBar("Combine Sprites", "combing 0", 1);
                    CombineSpritesHelper(path, dpath, obj.name, 1);
                }
            }
        }
        catch (System.Exception e)
        {
            Debug.LogError(e);
        }
        EditorUtility.ClearProgressBar();
    }

使用方法很简单，可以修改源码中的路径，可以将多个Single Sprite合成一个Multi Sprite。然后在供，UGUI使用，注意最好保存好合并前的源文件，不然可能造成新增图片打图集后对应不上从而造成引用丢失。

补充UITextPacker.cs ：引用自NGUI

/*
    Based on the Public Domain MaxRectsBinPack.cpp source by Jukka Jylänki
    https://github.com/juj/RectangleBinPack/

    Ported to C# by Sven Magnus
    This version is also public domain - do whatever you want with it.
*/
using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class UITexturePacker
{
    public int binWidth = 0;
    public int binHeight = 0;
    public bool allowRotations;

    public List<Rect> usedRectangles = new List<Rect>();
    public List<Rect> freeRectangles = new List<Rect>();

    public enum FreeRectChoiceHeuristic
    {
        RectBestShortSideFit, ///< -BSSF: Positions the rectangle against the short side of a free rectangle into which it fits the best.
        RectBestLongSideFit, ///< -BLSF: Positions the rectangle against the long side of a free rectangle into which it fits the best.
        RectBestAreaFit, ///< -BAF: Positions the rectangle into the smallest free rect into which it fits.
        RectBottomLeftRule, ///< -BL: Does the Tetris placement.
        RectContactPointRule ///< -CP: Choosest the placement where the rectangle touches other rects as much as possible.
    };

    public UITexturePacker (int width, int height, bool rotations)
    {
        Init(width, height, rotations);
    }

    public void Init (int width, int height, bool rotations)
    {
        binWidth = width;
        binHeight = height;
        allowRotations = rotations;

        Rect n = new Rect();
        n.x = 0;
        n.y = 0;
        n.width = width;
        n.height = height;

        usedRectangles.Clear();

        freeRectangles.Clear();
        freeRectangles.Add(n);
    }

    private struct Storage
    {
        public Rect rect;
        public bool paddingX;
        public bool paddingY;
    }

    public static Rect[] PackTextures (Texture2D texture, Texture2D[] textures, int width, int height, int padding, int maxSize)
    {
        if (width > maxSize || height > maxSize) return null;
        if (width > maxSize || height > maxSize) { int temp = width; width = height; height = temp; }
        
        // Force square by sizing up
        /*
        if (NGUISettings.forceSquareAtlas)
        {
            if (width > height)
                height = width;
            else if (height > width)
                width = height;
        }
        */
        UITexturePacker bp = new UITexturePacker(width, height, false);
        Storage[] storage = new Storage[textures.Length];

        for (int i = 0; i < textures.Length; i++)
        {
            Texture2D tex = textures[i];
            if (!tex) continue;

            Rect rect = new Rect();

            int xPadding = 1;
            int yPadding = 1;

            for (xPadding = 1; xPadding >= 0; --xPadding)
            {
                for (yPadding = 1; yPadding >= 0; --yPadding)
                {
                    rect = bp.Insert(tex.width + (xPadding * padding), tex.height + (yPadding * padding),
                        UITexturePacker.FreeRectChoiceHeuristic.RectBestAreaFit);
                    if (rect.width != 0 && rect.height != 0) break;

                    // After having no padding if it still doesn't fit -- increase texture size.
                    else if (xPadding == 0 && yPadding == 0)
                    {
                        return PackTextures(texture, textures, width * (width <= height ? 2 : 1),
                            height * (height < width ? 2 : 1), padding, maxSize);
                    }
                }
                if (rect.width != 0 && rect.height != 0) break;
            }

            storage[i] = new Storage();
            storage[i].rect = rect;
            storage[i].paddingX = (xPadding != 0);
            storage[i].paddingY = (yPadding != 0);
        }

        texture.Resize(width, height);
        texture.SetPixels(new Color[width * height]);

        // The returned rects
        Rect[] rects = new Rect[textures.Length];

        for (int i = 0; i < textures.Length; i++)
        {
            Texture2D tex = textures[i];
            if (!tex) continue;

            Rect rect = storage[i].rect;
            int xPadding = (storage[i].paddingX ? padding : 0);
            int yPadding = (storage[i].paddingY ? padding : 0);
            Color[] colors = tex.GetPixels();

            // Would be used to rotate the texture if need be.
            if (rect.width != tex.width + xPadding)
            {
                Color[] newColors = tex.GetPixels();

                for (int x = 0; x < rect.width; x++)
                {
                    for (int y = 0; y < rect.height; y++)
                    {
                        int prevIndex = ((int)rect.height - (y + 1)) + x * (int)tex.width;
                        newColors[x + y * (int)rect.width] = colors[prevIndex];
                    }
                }

                colors = newColors;
            }

            texture.SetPixels((int)rect.x, (int)rect.y, (int)rect.width - xPadding, (int)rect.height - yPadding, colors);
            rect.x /= width;
            rect.y /= height;
            rect.width = (rect.width - xPadding) / width;
            rect.height = (rect.height - yPadding) / height;
            rects[i] = rect;
        }
        texture.Apply();
        return rects;
    }

    public Rect Insert (int width, int height, FreeRectChoiceHeuristic method)
    {
        Rect newNode = new Rect();
        int score1 = 0; // Unused in this function. We don't need to know the score after finding the position.
        int score2 = 0;
        switch (method)
        {
            case FreeRectChoiceHeuristic.RectBestShortSideFit: newNode = FindPositionForNewNodeBestShortSideFit(width, height, ref score1, ref score2); break;
            case FreeRectChoiceHeuristic.RectBottomLeftRule: newNode = FindPositionForNewNodeBottomLeft(width, height, ref score1, ref score2); break;
            case FreeRectChoiceHeuristic.RectContactPointRule: newNode = FindPositionForNewNodeContactPoint(width, height, ref score1); break;
            case FreeRectChoiceHeuristic.RectBestLongSideFit: newNode = FindPositionForNewNodeBestLongSideFit(width, height, ref score2, ref score1); break;
            case FreeRectChoiceHeuristic.RectBestAreaFit: newNode = FindPositionForNewNodeBestAreaFit(width, height, ref score1, ref score2); break;
        }

        if (newNode.height == 0)
            return newNode;

        int numRectanglesToProcess = freeRectangles.Count;
        for (int i = 0; i < numRectanglesToProcess; ++i)
        {
            if (SplitFreeNode(freeRectangles[i], ref newNode))
            {
                freeRectangles.RemoveAt(i);
                --i;
                --numRectanglesToProcess;
            }
        }

        PruneFreeList();

        usedRectangles.Add(newNode);
        return newNode;
    }

    public void Insert (List<Rect> rects, List<Rect> dst, FreeRectChoiceHeuristic method)
    {
        dst.Clear();

        while (rects.Count > 0)
        {
            int bestScore1 = int.MaxValue;
            int bestScore2 = int.MaxValue;
            int bestRectIndex = -1;
            Rect bestNode = new Rect();

            for (int i = 0; i < rects.Count; ++i)
            {
                int score1 = 0;
                int score2 = 0;
                Rect newNode = ScoreRect((int)rects[i].width, (int)rects[i].height, method, ref score1, ref score2);

                if (score1 < bestScore1 || (score1 == bestScore1 && score2 < bestScore2))
                {
                    bestScore1 = score1;
                    bestScore2 = score2;
                    bestNode = newNode;
                    bestRectIndex = i;
                }
            }

            if (bestRectIndex == -1)
                return;

            PlaceRect(bestNode);
            rects.RemoveAt(bestRectIndex);
        }
    }

    void PlaceRect (Rect node)
    {
        int numRectanglesToProcess = freeRectangles.Count;
        for (int i = 0; i < numRectanglesToProcess; ++i)
        {
            if (SplitFreeNode(freeRectangles[i], ref node))
            {
                freeRectangles.RemoveAt(i);
                --i;
                --numRectanglesToProcess;
            }
        }

        PruneFreeList();

        usedRectangles.Add(node);
    }

    Rect ScoreRect (int width, int height, FreeRectChoiceHeuristic method, ref int score1, ref int score2)
    {
        Rect newNode = new Rect();
        score1 = int.MaxValue;
        score2 = int.MaxValue;
        switch (method)
        {
            case FreeRectChoiceHeuristic.RectBestShortSideFit: newNode = FindPositionForNewNodeBestShortSideFit(width, height, ref score1, ref score2); break;
            case FreeRectChoiceHeuristic.RectBottomLeftRule: newNode = FindPositionForNewNodeBottomLeft(width, height, ref score1, ref score2); break;
            case FreeRectChoiceHeuristic.RectContactPointRule: newNode = FindPositionForNewNodeContactPoint(width, height, ref score1);
            score1 = -score1; // Reverse since we are minimizing, but for contact point score bigger is better.
            break;
            case FreeRectChoiceHeuristic.RectBestLongSideFit: newNode = FindPositionForNewNodeBestLongSideFit(width, height, ref score2, ref score1); break;
            case FreeRectChoiceHeuristic.RectBestAreaFit: newNode = FindPositionForNewNodeBestAreaFit(width, height, ref score1, ref score2); break;
        }

        // Cannot fit the current rectangle.
        if (newNode.height == 0)
        {
            score1 = int.MaxValue;
            score2 = int.MaxValue;
        }

        return newNode;
    }

    /// Computes the ratio of used surface area.
    public float Occupancy ()
    {
        ulong usedSurfaceArea = 0;
        for (int i = 0; i < usedRectangles.Count; ++i)
            usedSurfaceArea += (uint)usedRectangles[i].width * (uint)usedRectangles[i].height;

        return (float)usedSurfaceArea / (binWidth * binHeight);
    }

    Rect FindPositionForNewNodeBottomLeft (int width, int height, ref int bestY, ref int bestX)
    {
        Rect bestNode = new Rect();
        //memset(bestNode, 0, sizeof(Rect));

        bestY = int.MaxValue;

        for (int i = 0; i < freeRectangles.Count; ++i)
        {
            // Try to place the rectangle in upright (non-flipped) orientation.
            if (freeRectangles[i].width >= width && freeRectangles[i].height >= height)
            {
                int topSideY = (int)freeRectangles[i].y + height;
                if (topSideY < bestY || (topSideY == bestY && freeRectangles[i].x < bestX))
                {
                    bestNode.x = freeRectangles[i].x;
                    bestNode.y = freeRectangles[i].y;
                    bestNode.width = width;
                    bestNode.height = height;
                    bestY = topSideY;
                    bestX = (int)freeRectangles[i].x;
                }
            }
            if (allowRotations && freeRectangles[i].width >= height && freeRectangles[i].height >= width)
            {
                int topSideY = (int)freeRectangles[i].y + width;
                if (topSideY < bestY || (topSideY == bestY && freeRectangles[i].x < bestX))
                {
                    bestNode.x = freeRectangles[i].x;
                    bestNode.y = freeRectangles[i].y;
                    bestNode.width = height;
                    bestNode.height = width;
                    bestY = topSideY;
                    bestX = (int)freeRectangles[i].x;
                }
            }
        }
        return bestNode;
    }

    Rect FindPositionForNewNodeBestShortSideFit (int width, int height, ref int bestShortSideFit, ref int bestLongSideFit)
    {
        Rect bestNode = new Rect();
        //memset(&bestNode, 0, sizeof(Rect));

        bestShortSideFit = int.MaxValue;

        for (int i = 0; i < freeRectangles.Count; ++i)
        {
            // Try to place the rectangle in upright (non-flipped) orientation.
            if (freeRectangles[i].width >= width && freeRectangles[i].height >= height)
            {
                int leftoverHoriz = Mathf.Abs((int)freeRectangles[i].width - width);
                int leftoverVert = Mathf.Abs((int)freeRectangles[i].height - height);
                int shortSideFit = Mathf.Min(leftoverHoriz, leftoverVert);
                int longSideFit = Mathf.Max(leftoverHoriz, leftoverVert);

                if (shortSideFit < bestShortSideFit || (shortSideFit == bestShortSideFit && longSideFit < bestLongSideFit))
                {
                    bestNode.x = freeRectangles[i].x;
                    bestNode.y = freeRectangles[i].y;
                    bestNode.width = width;
                    bestNode.height = height;
                    bestShortSideFit = shortSideFit;
                    bestLongSideFit = longSideFit;
                }
            }

            if (allowRotations && freeRectangles[i].width >= height && freeRectangles[i].height >= width)
            {
                int flippedLeftoverHoriz = Mathf.Abs((int)freeRectangles[i].width - height);
                int flippedLeftoverVert = Mathf.Abs((int)freeRectangles[i].height - width);
                int flippedShortSideFit = Mathf.Min(flippedLeftoverHoriz, flippedLeftoverVert);
                int flippedLongSideFit = Mathf.Max(flippedLeftoverHoriz, flippedLeftoverVert);

                if (flippedShortSideFit < bestShortSideFit || (flippedShortSideFit == bestShortSideFit && flippedLongSideFit < bestLongSideFit))
                {
                    bestNode.x = freeRectangles[i].x;
                    bestNode.y = freeRectangles[i].y;
                    bestNode.width = height;
                    bestNode.height = width;
                    bestShortSideFit = flippedShortSideFit;
                    bestLongSideFit = flippedLongSideFit;
                }
            }
        }
        return bestNode;
    }

    Rect FindPositionForNewNodeBestLongSideFit (int width, int height, ref int bestShortSideFit, ref int bestLongSideFit)
    {
        Rect bestNode = new Rect();
        //memset(&bestNode, 0, sizeof(Rect));

        bestLongSideFit = int.MaxValue;

        for (int i = 0; i < freeRectangles.Count; ++i)
        {
            // Try to place the rectangle in upright (non-flipped) orientation.
            if (freeRectangles[i].width >= width && freeRectangles[i].height >= height)
            {
                int leftoverHoriz = Mathf.Abs((int)freeRectangles[i].width - width);
                int leftoverVert = Mathf.Abs((int)freeRectangles[i].height - height);
                int shortSideFit = Mathf.Min(leftoverHoriz, leftoverVert);
                int longSideFit = Mathf.Max(leftoverHoriz, leftoverVert);

                if (longSideFit < bestLongSideFit || (longSideFit == bestLongSideFit && shortSideFit < bestShortSideFit))
                {
                    bestNode.x = freeRectangles[i].x;
                    bestNode.y = freeRectangles[i].y;
                    bestNode.width = width;
                    bestNode.height = height;
                    bestShortSideFit = shortSideFit;
                    bestLongSideFit = longSideFit;
                }
            }

            if (allowRotations && freeRectangles[i].width >= height && freeRectangles[i].height >= width)
            {
                int leftoverHoriz = Mathf.Abs((int)freeRectangles[i].width - height);
                int leftoverVert = Mathf.Abs((int)freeRectangles[i].height - width);
                int shortSideFit = Mathf.Min(leftoverHoriz, leftoverVert);
                int longSideFit = Mathf.Max(leftoverHoriz, leftoverVert);

                if (longSideFit < bestLongSideFit || (longSideFit == bestLongSideFit && shortSideFit < bestShortSideFit))
                {
                    bestNode.x = freeRectangles[i].x;
                    bestNode.y = freeRectangles[i].y;
                    bestNode.width = height;
                    bestNode.height = width;
                    bestShortSideFit = shortSideFit;
                    bestLongSideFit = longSideFit;
                }
            }
        }
        return bestNode;
    }

    Rect FindPositionForNewNodeBestAreaFit (int width, int height, ref int bestAreaFit, ref int bestShortSideFit)
    {
        Rect bestNode = new Rect();
        //memset(&bestNode, 0, sizeof(Rect));

        bestAreaFit = int.MaxValue;

        for (int i = 0; i < freeRectangles.Count; ++i)
        {
            int areaFit = (int)freeRectangles[i].width * (int)freeRectangles[i].height - width * height;

            // Try to place the rectangle in upright (non-flipped) orientation.
            if (freeRectangles[i].width >= width && freeRectangles[i].height >= height)
            {
                int leftoverHoriz = Mathf.Abs((int)freeRectangles[i].width - width);
                int leftoverVert = Mathf.Abs((int)freeRectangles[i].height - height);
                int shortSideFit = Mathf.Min(leftoverHoriz, leftoverVert);

                if (areaFit < bestAreaFit || (areaFit == bestAreaFit && shortSideFit < bestShortSideFit))
                {
                    bestNode.x = freeRectangles[i].x;
                    bestNode.y = freeRectangles[i].y;
                    bestNode.width = width;
                    bestNode.height = height;
                    bestShortSideFit = shortSideFit;
                    bestAreaFit = areaFit;
                }
            }

            if (allowRotations && freeRectangles[i].width >= height && freeRectangles[i].height >= width)
            {
                int leftoverHoriz = Mathf.Abs((int)freeRectangles[i].width - height);
                int leftoverVert = Mathf.Abs((int)freeRectangles[i].height - width);
                int shortSideFit = Mathf.Min(leftoverHoriz, leftoverVert);

                if (areaFit < bestAreaFit || (areaFit == bestAreaFit && shortSideFit < bestShortSideFit))
                {
                    bestNode.x = freeRectangles[i].x;
                    bestNode.y = freeRectangles[i].y;
                    bestNode.width = height;
                    bestNode.height = width;
                    bestShortSideFit = shortSideFit;
                    bestAreaFit = areaFit;
                }
            }
        }
        return bestNode;
    }

    /// Returns 0 if the two intervals i1 and i2 are disjoint, or the length of their overlap otherwise.
    int CommonIntervalLength (int i1start, int i1end, int i2start, int i2end)
    {
        if (i1end < i2start || i2end < i1start)
            return 0;
        return Mathf.Min(i1end, i2end) - Mathf.Max(i1start, i2start);
    }

    int ContactPointScoreNode (int x, int y, int width, int height)
    {
        int score = 0;

        if (x == 0 || x + width == binWidth)
            score += height;
        if (y == 0 || y + height == binHeight)
            score += width;

        for (int i = 0; i < usedRectangles.Count; ++i)
        {
            if (usedRectangles[i].x == x + width || usedRectangles[i].x + usedRectangles[i].width == x)
                score += CommonIntervalLength((int)usedRectangles[i].y, (int)usedRectangles[i].y + (int)usedRectangles[i].height, y, y + height);
            if (usedRectangles[i].y == y + height || usedRectangles[i].y + usedRectangles[i].height == y)
                score += CommonIntervalLength((int)usedRectangles[i].x, (int)usedRectangles[i].x + (int)usedRectangles[i].width, x, x + width);
        }
        return score;
    }

    Rect FindPositionForNewNodeContactPoint (int width, int height, ref int bestContactScore)
    {
        Rect bestNode = new Rect();
        //memset(&bestNode, 0, sizeof(Rect));

        bestContactScore = -1;

        for (int i = 0; i < freeRectangles.Count; ++i)
        {
            // Try to place the rectangle in upright (non-flipped) orientation.
            if (freeRectangles[i].width >= width && freeRectangles[i].height >= height)
            {
                int score = ContactPointScoreNode((int)freeRectangles[i].x, (int)freeRectangles[i].y, width, height);
                if (score > bestContactScore)
                {
                    bestNode.x = (int)freeRectangles[i].x;
                    bestNode.y = (int)freeRectangles[i].y;
                    bestNode.width = width;
                    bestNode.height = height;
                    bestContactScore = score;
                }
            }
            if (allowRotations && freeRectangles[i].width >= height && freeRectangles[i].height >= width)
            {
                int score = ContactPointScoreNode((int)freeRectangles[i].x, (int)freeRectangles[i].y, height, width);
                if (score > bestContactScore)
                {
                    bestNode.x = (int)freeRectangles[i].x;
                    bestNode.y = (int)freeRectangles[i].y;
                    bestNode.width = height;
                    bestNode.height = width;
                    bestContactScore = score;
                }
            }
        }
        return bestNode;
    }

    bool SplitFreeNode (Rect freeNode, ref Rect usedNode)
    {
        // Test with SAT if the rectangles even intersect.
        if (usedNode.x >= freeNode.x + freeNode.width || usedNode.x + usedNode.width <= freeNode.x ||
            usedNode.y >= freeNode.y + freeNode.height || usedNode.y + usedNode.height <= freeNode.y)
            return false;

        if (usedNode.x < freeNode.x + freeNode.width && usedNode.x + usedNode.width > freeNode.x)
        {
            // New node at the top side of the used node.
            if (usedNode.y > freeNode.y && usedNode.y < freeNode.y + freeNode.height)
            {
                Rect newNode = freeNode;
                newNode.height = usedNode.y - newNode.y;
                freeRectangles.Add(newNode);
            }

            // New node at the bottom side of the used node.
            if (usedNode.y + usedNode.height < freeNode.y + freeNode.height)
            {
                Rect newNode = freeNode;
                newNode.y = usedNode.y + usedNode.height;
                newNode.height = freeNode.y + freeNode.height - (usedNode.y + usedNode.height);
                freeRectangles.Add(newNode);
            }
        }

        if (usedNode.y < freeNode.y + freeNode.height && usedNode.y + usedNode.height > freeNode.y)
        {
            // New node at the left side of the used node.
            if (usedNode.x > freeNode.x && usedNode.x < freeNode.x + freeNode.width)
            {
                Rect newNode = freeNode;
                newNode.width = usedNode.x - newNode.x;
                freeRectangles.Add(newNode);
            }

            // New node at the right side of the used node.
            if (usedNode.x + usedNode.width < freeNode.x + freeNode.width)
            {
                Rect newNode = freeNode;
                newNode.x = usedNode.x + usedNode.width;
                newNode.width = freeNode.x + freeNode.width - (usedNode.x + usedNode.width);
                freeRectangles.Add(newNode);
            }
        }

        return true;
    }

    void PruneFreeList ()
    {
        for (int i = 0; i < freeRectangles.Count; ++i)
            for (int j = i + 1; j < freeRectangles.Count; ++j)
            {
                if (IsContainedIn(freeRectangles[i], freeRectangles[j]))
                {
                    freeRectangles.RemoveAt(i);
                    --i;
                    break;
                }
                if (IsContainedIn(freeRectangles[j], freeRectangles[i]))
                {
                    freeRectangles.RemoveAt(j);
                    --j;
                }
            }
    }

    bool IsContainedIn (Rect a, Rect b)
    {
        return a.x >= b.x && a.y >= b.y
            && a.x + a.width <= b.x + b.width
            && a.y + a.height <= b.y + b.height;
    }
}

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