Simple example of BSP dungeon generation

Question

I was originally trying to follow this algorithm to create a little simple roguelike dungeon in C#. But I guess I'm just too stupid, because my result always came out a jumbled mess of crap.

I then switched over to my own algorithm, which produces not-great but semi-recognizable-as-a-dungeon results.

Does anyone have any examples of doing it the BSP way, as described in the linked article? It would be best if it weren't encumbered by a bunch of game details/library calls, because (again) I'm stupid.

(If you're especially masochistic and want me to post the code I had, I can, but I figured it'd be too much for an SO question.)

Answer 1

This doesn't link the rooms yet, but it generates okay dungeons using the algorithm described. (Unfortunately it is in Java but I tried to add some comments to clarify what is being done.)

public static class Rectangle {  

    private static int MIN_SIZE = 5;
    private static Random rnd = new Random(); 

    private int top, left, width, height;
    private Rectangle leftChild;
    private Rectangle rightChild;
    private Rectangle dungeon;

    public Rectangle(int top, int left, int height, int width) {
        this.top = top;
        this.left = left;
        this.width = width;
        this.height = height;
    }

    public boolean split() {
        if( leftChild != null ) //if already split, bail out
            return false;
        boolean horizontal = rnd.nextBoolean(); //direction of split
        int max = (horizontal ? height : width ) - MIN_SIZE; //maximum height/width we can split off
        if( max <= MIN_SIZE ) // area too small to split, bail out
            return false;
        int split = rnd.nextInt( max ); // generate split point 
        if( split < MIN_SIZE )  // adjust split point so there's at least MIN_SIZE in both partitions
            split = MIN_SIZE;
        if( horizontal ) { //populate child areas
            leftChild = new Rectangle( top, left, split, width ); 
            rightChild = new Rectangle( top+split, left, height-split, width );
        } else {
            leftChild = new Rectangle( top, left, height, split );
            rightChild = new Rectangle( top, left+split, height, width-split );
        }
        return true; //split successful
    }

    public void generateDungeon() {
        if( leftChild != null ) { //if current are has child areas, propagate the call
            leftChild.generateDungeon();
            rightChild.generateDungeon();
        } else { // if leaf node, create a dungeon within the minimum size constraints
            int dungeonTop = (height - MIN_SIZE <= 0) ? 0 : rnd.nextInt( height - MIN_SIZE);
            int dungeonLeft =  (width - MIN_SIZE <= 0) ? 0 : rnd.nextInt( width - MIN_SIZE);
            int dungeonHeight = Math.max(rnd.nextInt( height - dungeonTop ), MIN_SIZE );;
            int dungeonWidth = Math.max(rnd.nextInt( width - dungeonLeft ), MIN_SIZE );;
            dungeon = new Rectangle( top + dungeonTop, left+dungeonLeft, dungeonHeight, dungeonWidth);
        }
    }

}

And here's a test class to demonstrate its usage:

import java.util.ArrayList;
import java.util.Random;


public class GenerateDungeon {

    private static Random rnd = new Random(); 



    public static void main(String[] args) {
        ArrayList<Rectangle> rectangles = new ArrayList<Rectangle>(); // flat rectangle store to help pick a random one
        Rectangle root = new Rectangle( 0, 0, 60, 120 ); //
        rectangles.add( root  ); //populate rectangle store with root area
        while( rectangles.size() < 19 ) { // this will give us 10 leaf areas
            int splitIdx = rnd.nextInt( rectangles.size() ); // choose a random element
            Rectangle toSplit = rectangles.get( splitIdx); 
            if( toSplit.split() ) { //attempt to split
                rectangles.add( toSplit.leftChild );
                rectangles.add( toSplit.rightChild );
            } 

        }
        root.generateDungeon(); //generate dungeons

        printDungeons(rectangles); //this is just to test the output

    }



    private static void printDungeons(ArrayList<Rectangle> rectangles) {
        byte [][] lines = new byte[60][];
        for( int i = 0; i < 60; i++ ) {
            lines[ i ] = new byte[120];
            for( int j = 0; j < 120; j++ )
                lines[ i ][ j ] =  -1;
        }
        byte dungeonCount = -1;
        for( Rectangle r : rectangles ) {
            if( r.dungeon == null )
                continue;
            Rectangle d = r.dungeon;
            dungeonCount++;
            for( int i = 0; i < d.height; i++ ) {
                for( int j = 0; j < d.width; j++ )

                    lines[ d.top + i ][ d.left+ j ] = dungeonCount;
            }
        }
        for( int i = 0; i < 60; i++ ) {
            for( int j = 0; j < 120; j++ ) {
                if( lines[ i ][ j ] == -1 )
                    System.out.print( '.');
                else
                    System.out.print( lines[ i ][ j ] );
            }
            System.out.println();
        }
    }

}

Answer 2

your version in java helped me and I decided to sketch it in c # maybe will help anyone

public class BspTree
{
public RectInt container;
public RectInt room;
public BspTree left;
public BspTree right;

public BspTree(RectInt a)
{
    container = a;
}

internal static BspTree Split(int numberOfOperations, RectInt container)
{
    var node = new BspTree(container);  

    if (numberOfOperations == 0)
    {
        return node;
    }

    var splitedContainer = SplitContainer(container);
    node.left = Split(numberOfOperations - 1, splitedContainer[0]);
    Debug.Log(numberOfOperations);

    node.right = Split(numberOfOperations - 1, splitedContainer[1]);
    Debug.Log(numberOfOperations);

    return node;
}

private static RectInt[] SplitContainer(RectInt container)
{
    RectInt c1, c2;
    bool horizontal = Random.Range(0f, 1f) > 0.5f ? true : false;
    if (horizontal)
    {
        c1 = new RectInt(container.x, container.y, (int)(container.width * Random.Range(0.3f, 0.6f)), container.height);
        c2 = new RectInt(container.x + c1.width, container.y, container.width - c1.width, container.height);
    }
    else
    {
        c1 = new RectInt(container.x, container.y, container.width, (int)(container.height * Random.Range(0.3f, 0.6f)));
        c2 = new RectInt(container.x, container.y + c1.height, container.width, container.height - c1.height);
    }
    return new RectInt[] { c1, c2 };
}

}

and to use it in a unity with monobehaviour

public class DungeonCreator : MonoBehaviour
{
[Range (1, 400)]
public int widthRange;
public bool shouldDebugDrawBsp;

private BspTree tree;

void Start()
{
    RectInt rect = new RectInt(0, 0, widthRange, widthRange);
    tree = BspTree.Split(4, rect);
}

public void DebugDrawBsp()
{
    if (tree == null) return; 

    DebugDrawBspNode(tree); 
}

public void DebugDrawBspNode(BspTree node)
{
    // Container
    Gizmos.color = Color.green;
    // top      
    Gizmos.DrawLine(new Vector3(node.container.x, node.container.y, 0), new Vector3Int(node.container.xMax, node.container.y, 0));
    // right
    Gizmos.DrawLine(new Vector3(node.container.xMax, node.container.y, 0), new Vector3Int(node.container.xMax, node.container.yMax, 0));
    // bottom
    Gizmos.DrawLine(new Vector3(node.container.x, node.container.yMax, 0), new Vector3Int(node.container.xMax, node.container.yMax, 0));
    // left
    Gizmos.DrawLine(new Vector3(node.container.x, node.container.y, 0), new Vector3Int(node.container.x, node.container.yMax, 0));

    // children
    if (node.left != null) DebugDrawBspNode(node.left);
    if (node.right != null) DebugDrawBspNode(node.right);
}

private void OnDrawGizmos()
{
    if (shouldDebugDrawBsp)
    {
        DebugDrawBsp();
    }
}
}