Dungeon-Building Algorithm
Revision as of 04:39, 27 January 2008 by Pi is 3.14159 (talk | contribs) (→Java example: make smaller)
(Originally written by Mike Anderson. Please note that this guide only contains the essential parts about the algorithm, nothing else from his guide)
In this algorithm a "feature" is taken to mean any kind of map component
e.g. large room, small room, corridor, circular arena, vault etc.
1. Fill the whole map with solid earth
2. Dig out a single room in the centre of the map
3. Pick a wall of any room
4. Decide upon a new feature to build
5. See if there is room to add the new feature through the chosen wall
6. If yes, continue. If no, go back to step 3
7. Add the feature through the chosen wall
8. Go back to step 3, until the dungeon is complete
9. Add the up and down staircases at random points in map
10. Finally, sprinkle some monsters and items liberally over dungeon
Step 1 and 2 are easy once you've got the map set up. I have found it very
useful to write a "fillRect" command that fills a rectangular map area
with a specified tile type.
Step 3 is trickier. You can't pick random squares to add new features
because the rule is to always add to the existing dungeon. This makes the
connections look good, and also guarantees that every square is reachable.
The way Tyrant does it is to pick random squares on the map until it finds
a wall square adjacent (horizontally or vertically) to a clear square.
This is a good method, since it gives you a roughly even chance of picking
any particular wall square.
Step 4 isn't too hard - I just use a random switch statement to determine
which of a range of features to build. You can change the whole look of
the map by weighting the probabilities of different features. Well-ordered
dungeons will have lots of regular rooms and long straight corridors. Cave
complexes will tend to have jagged caverns, twisting passages etc.
Step 5 is more tricky, and the key to the whole algorithm. For each
feature, you need to know the area of the map that it will occupy. Then
you need to scan outwards from the chosen wall to see if this area
intersects any features that are already there. Tyrant does this in a
fairly simplistic way - it just works out the rectangular space that the
new feature will occupy plus a square on each side for walls, then checks
to see if the entire rectangle is currently filled with solid earth.
Step 6 decides whether or not to add the feature. If the area under
consideration contains anything other than solid earth already, then the
routine loops back to step 3. Note that *most* new features will be
rejected in this way. This isn't a problem, as the processing time is
negligible. Tyrant tries to add 300 or so features to each dungeon, but
usually only 40 or so make it past this stage.
Step 7 draws the new feature once you've decided the area is OK. In this
stage, you can also add any interesting room features, such as
inhabitants, traps, secret doors and treasure.
Step 8 just loops back to build more rooms. The exact number of times that
you want to do this will depend on map size and various other factors.
Step 9 is pretty self-explanatory. Easiest way to do it is to write a
routine that picks random squares until it finds an empty one where the
staircases can be added.
Step 10 just creates a host of extra random monsters in random locations
to add some spice. Tyrant creates about most of the monsters at this point
of the map generation, although it does add a few special creatures when
individual rooms are generated.
Java example
(Made by Solarnus)
import java.lang.Integer; //so we can use Integer.parseInt()
import java.util.*; //and for getting today's date
public class dungen{
//max size of the map
private int xmax = 80; //80 columns
private int ymax = 25; //25 rows
//size of the map
private int xsize = 0;
private int ysize = 0;
//number of "objects" to generate on the map
private int objects = 0;
//define the %chance to generate either a room or a corridor on the map
//BTW, rooms are 1st priority so actually it's enough to just define the chance
//of generating a room
private int chanceRoom = 75;
private int chanceCorridor = 25;
//our map
private int[] dungeon_map = new int[0];
//the old seed from the RNG is saved in this one
private long oldseed = 0;
//a list over tile types we're using
final private int tileUnused = 0;
final private int tileDirtWall = 1; //not in use
final private int tileDirtFloor = 2;
final private int tileStoneWall = 3;
final private int tileCorridor = 4;
final private int tileDoor = 5;
final private int tileUpStairs = 6;
final private int tileDownStairs = 7;
final private int tileChest = 8;
//misc. messages to print
private String msgXSize = "X size of dungeon: \t";
private String msgYSize = "Y size of dungeon: \t";
private String msgMaxObjects = "max # of objects: \t";
private String msgNumObjects = "# of objects made: \t";
private String msgHelp = "";
private String msgDetailedHelp = "";
//setting a tile's type
private void setCell(int x, int y, int celltype){
dungeon_map[x + xsize * y] = celltype;
}
//returns the type of a tile
private int getCell(int x, int y){
return dungeon_map[x + xsize * y];
}
//The RNG. the seed is based on seconds from the "java epoch" ( I think..)
//perhaps it's the same date as the unix epoch
private int getRand(int min, int max){
//the seed is based on current date and the old, already used seed
Date now = new Date();
long seed = now.getTime() + oldseed;
oldseed = seed;
Random randomizer = new Random(seed);
int n = max - min + 1;
int i = randomizer.nextInt() % n;
if (i < 0)
i = -i;
//System.out.println("seed: " + seed + "\tnum: " + (min + i));
return min + i;
}
private boolean makeCorridor(int x, int y, int lenght, int direction){
//define the dimensions of the corridor (er.. only the width and height..)
int len = getRand(2, lenght);
int floor = tileCorridor;
int dir = 0;
if (direction > 0 && direction < 4) dir = direction;
int xtemp = 0;
int ytemp = 0;
switch(dir){
case 0:
//north
//check if there's enough space for the corridor
//start with checking it's not out of the boundaries
if (x < 0 || x > xsize) return false;
else xtemp = x;
//same thing here, to make sure it's not out of the boundaries
for (ytemp = y; ytemp > (y-len); ytemp--){
if (ytemp < 0 || ytemp > ysize) return false; //oh boho, it was!
if (getCell(xtemp, ytemp) != tileUnused) return false;
}
//if we're still here, let's start building
for (ytemp = y; ytemp > (y-len); ytemp--){
setCell(xtemp, ytemp, floor);
}
break;
case 1:
//east
if (y < 0 || y > ysize) return false;
else ytemp = y;
for (xtemp = x; xtemp < (x+len); xtemp++){
if (xtemp < 0 || xtemp > xsize) return false;
if (getCell(xtemp, ytemp) != tileUnused) return false;
}
for (xtemp = x; xtemp < (x+len); xtemp++){
setCell(xtemp, ytemp, floor);
}
break;
case 2:
//south
if (x < 0 || x > xsize) return false;
else xtemp = x;
for (ytemp = y; ytemp < (y+len); ytemp++){
if (ytemp < 0 || ytemp > ysize) return false;
if (getCell(xtemp, ytemp) != tileUnused) return false;
}
for (ytemp = y; ytemp < (y+len); ytemp++){
setCell(xtemp, ytemp, floor);
}
break;
case 3:
//west
if (ytemp < 0 || ytemp > ysize) return false;
else ytemp = y;
for (xtemp = x; xtemp > (x-len); xtemp--){
if (xtemp < 0 || xtemp > xsize) return false;
if (getCell(xtemp, ytemp) != tileUnused) return false;
}
for (xtemp = x; xtemp > (x-len); xtemp--){
setCell(xtemp, ytemp, floor);
}
break;
}
//woot, we're still here! let's tell the other guys we're done!!
return true;
}
private boolean makeRoom(int x, int y, int xlength, int ylength, int direction){
//define the dimensions of the room, it should be at least 4x4 tiles (2x2 for walking on, the rest is walls)
int xlen = getRand(4, xlength);
int ylen = getRand(4, ylength);
//the tile type it's going to be filled with
int floor = tileDirtFloor; //jordgolv..
int wall = tileDirtWall; //jordv????gg
//choose the way it's pointing at
int dir = 0;
if (direction > 0 && direction < 4) dir = direction;
switch(dir){
case 0:
//north
//Check if there's enough space left for it
for (int ytemp = y; ytemp > (y-ylen); ytemp--){
if (ytemp < 0 || ytemp > ysize) return false;
for (int xtemp = (x-xlen/2); xtemp < (x+(xlen+1)/2); xtemp++){
if (xtemp < 0 || xtemp > xsize) return false;
if (getCell(xtemp, ytemp) != tileUnused) return false; //no space left...
}
}
//we're still here, build
for (int ytemp = y; ytemp > (y-ylen); ytemp--){
for (int xtemp = (x-xlen/2); xtemp < (x+(xlen+1)/2); xtemp++){
//start with the walls
if (xtemp == (x-xlen/2)) setCell(xtemp, ytemp, wall);
else if (xtemp == (x+(xlen-1)/2)) setCell(xtemp, ytemp, wall);
else if (ytemp == y) setCell(xtemp, ytemp, wall);
else if (ytemp == (y-ylen+1)) setCell(xtemp, ytemp, wall);
//and then fill with the floor
else setCell(xtemp, ytemp, floor);
}
}
break;
case 1:
//east
for (int ytemp = (y-ylen/2); ytemp < (y+(ylen+1)/2); ytemp++){
if (ytemp < 0 || ytemp > ysize) return false;
for (int xtemp = x; xtemp < (x+xlen); xtemp++){
if (xtemp < 0 || xtemp > xsize) return false;
if (getCell(xtemp, ytemp) != tileUnused) return false;
}
}
for (int ytemp = (y-ylen/2); ytemp < (y+(ylen+1)/2); ytemp++){
for (int xtemp = x; xtemp < (x+xlen); xtemp++){
if (xtemp == x) setCell(xtemp, ytemp, wall);
else if (xtemp == (x+xlen-1)) setCell(xtemp, ytemp, wall);
else if (ytemp == (y-ylen/2)) setCell(xtemp, ytemp, wall);
else if (ytemp == (y+(ylen-1)/2)) setCell(xtemp, ytemp, wall);
else setCell(xtemp, ytemp, floor);
}
}
break;
case 2:
//south
for (int ytemp = y; ytemp < (y+ylen); ytemp++){
if (ytemp < 0 || ytemp > ysize) return false;
for (int xtemp = (x-xlen/2); xtemp < (x+(xlen+1)/2); xtemp++){
if (xtemp < 0 || xtemp > xsize) return false;
if (getCell(xtemp, ytemp) != tileUnused) return false;
}
}
for (int ytemp = y; ytemp < (y+ylen); ytemp++){
for (int xtemp = (x-xlen/2); xtemp < (x+(xlen+1)/2); xtemp++){
if (xtemp == (x-xlen/2)) setCell(xtemp, ytemp, wall);
else if (xtemp == (x+(xlen-1)/2)) setCell(xtemp, ytemp, wall);
else if (ytemp == y) setCell(xtemp, ytemp, wall);
else if (ytemp == (y+ylen-1)) setCell(xtemp, ytemp, wall);
else setCell(xtemp, ytemp, floor);
}
}
break;
case 3:
//west
for (int ytemp = (y-ylen/2); ytemp < (y+(ylen+1)/2); ytemp++){
if (ytemp < 0 || ytemp > ysize) return false;
for (int xtemp = x; xtemp > (x-xlen); xtemp--){
if (xtemp < 0 || xtemp > xsize) return false;
if (getCell(xtemp, ytemp) != tileUnused) return false;
}
}
for (int ytemp = (y-ylen/2); ytemp < (y+(ylen+1)/2); ytemp++){
for (int xtemp = x; xtemp > (x-xlen); xtemp--){
if (xtemp == x) setCell(xtemp, ytemp, wall);
else if (xtemp == (x-xlen+1)) setCell(xtemp, ytemp, wall);
else if (ytemp == (y-ylen/2)) setCell(xtemp, ytemp, wall);
else if (ytemp == (y+(ylen-1)/2)) setCell(xtemp, ytemp, wall);
else setCell(xtemp, ytemp, floor);
}
}
break;
}
//yay, all done
return true;
}
//used to print the map on the screen
public void showDungeon(){
for (int y = 0; y < ysize; y++){
for (int x = 0; x < xsize; x++){
//System.out.print(getCell(x, y));
switch(getCell(x, y)){
case tileUnused:
System.out.print(" ");
break;
case tileDirtWall:
System.out.print("+");
break;
case tileDirtFloor:
System.out.print(".");
break;
case tileStoneWall:
System.out.print("O");
break;
case tileCorridor:
System.out.print("#");
break;
case tileDoor:
System.out.print("D");
break;
case tileUpStairs:
System.out.print("<");
break;
case tileDownStairs:
System.out.print(">");
break;
case tileChest:
System.out.print("*");
break;
};
}
if (xsize < xmax) System.out.print("\n");
}
}
//and here's the one generating the whole map
public boolean createDungeon(int inx, int iny, int inobj){
if (inobj < 1) objects = 10;
else objects = inobj;
//justera kartans storlek, om den ????r st????rre eller mindre ????n "gr????nserna"
//adjust the size of the map, if it's smaller or bigger than the limits
if (inx < 3) xsize = 3;
else if (inx > xmax) xsize = xmax;
else xsize = inx;
if (iny < 3) ysize = 3;
else if (iny > ymax) ysize = ymax;
else ysize = iny;
System.out.println(msgXSize + xsize);
System.out.println(msgYSize + ysize);
System.out.println(msgMaxObjects + objects);
//redefine the map var, so it's adjusted to our new map size
dungeon_map = new int[xsize * ysize];
//start with making the "standard stuff" on the map
for (int y = 0; y < ysize; y++){
for (int x = 0; x < xsize; x++){
//ie, making the borders of unwalkable walls
if (y == 0) setCell(x, y, tileStoneWall);
else if (y == ysize-1) setCell(x, y, tileStoneWall);
else if (x == 0) setCell(x, y, tileStoneWall);
else if (x == xsize-1) setCell(x, y, tileStoneWall);
//and fill the rest with dirt
else setCell(x, y, tileUnused);
}
}
/*******************************************************************************
And now the code of the random-map-generation-algorithm begins!
*******************************************************************************/
//start with making a room in the middle, which we can start building upon
makeRoom(xsize/2, ysize/2, 8, 6, getRand(0,3)); //getrand saken f????r att slumpa fram riktning p?? rummet
//keep count of the number of "objects" we've made
int currentFeatures = 1; //+1 for the first room we just made
//then we sart the main loop
for (int countingTries = 0; countingTries < 1000; countingTries++){
//check if we've reached our quota
if (currentFeatures == objects){
break;
}
//start with a random wall
int newx = 0;
int xmod = 0;
int newy = 0;
int ymod = 0;
int validTile = -1;
//1000 chances to find a suitable object (room or corridor)..
//(yea, i know it's kinda ugly with a for-loop... -_-')
for (int testing = 0; testing < 1000; testing++){
newx = getRand(1, xsize-1);
newy = getRand(1, ysize-1);
validTile = -1;
//System.out.println("tempx: " + newx + "\ttempy: " + newy);
if (getCell(newx, newy) == tileDirtWall || getCell(newx, newy) == tileCorridor){
//check if we can reach the place
if (getCell(newx, newy+1) == tileDirtFloor || getCell(newx, newy+1) == tileCorridor){
validTile = 0; //
xmod = 0;
ymod = -1;
}
else if (getCell(newx-1, newy) == tileDirtFloor || getCell(newx-1, newy) == tileCorridor){
validTile = 1; //
xmod = +1;
ymod = 0;
}
else if (getCell(newx, newy-1) == tileDirtFloor || getCell(newx, newy-1) == tileCorridor){
validTile = 2; //
xmod = 0;
ymod = +1;
}
else if (getCell(newx+1, newy) == tileDirtFloor || getCell(newx+1, newy) == tileCorridor){
validTile = 3; //
xmod = -1;
ymod = 0;
}
//check that we haven't got another door nearby, so we won't get alot of openings besides
//each other
if (validTile > -1){
if (getCell(newx, newy+1) == tileDoor) //north
validTile = -1;
else if (getCell(newx-1, newy) == tileDoor)//east
validTile = -1;
else if (getCell(newx, newy-1) == tileDoor)//south
validTile = -1;
else if (getCell(newx+1, newy) == tileDoor)//west
validTile = -1;
}
//if we can, jump out of the loop and continue with the rest
if (validTile > -1) break;
}
}
if (validTile > -1){
//choose what to build now at our newly found place, and at what direction
int feature = getRand(0, 100);
if (feature <= chanceRoom){ //a new room
if (makeRoom((newx+xmod), (newy+ymod), 8, 6, validTile)){
currentFeatures++; //add to our quota
//then we mark the wall opening with a door
setCell(newx, newy, tileDoor);
//clean up infront of the door so we can reach it
setCell((newx+xmod), (newy+ymod), tileDirtFloor);
}
}
else if (feature >= chanceRoom){ //new corridor
if (makeCorridor((newx+xmod), (newy+ymod), 6, validTile)){
//same thing here, add to the quota and a door
currentFeatures++;
setCell(newx, newy, tileDoor);
}
}
}
}
/*******************************************************************************
All done with the building, let's finish this one off
*******************************************************************************/
//sprinkle out the bonusstuff (stairs, chests etc.) over the map
int newx = 0;
int newy = 0;
int ways = 0; //from how many directions we can reach the random spot from
int state = 0; //the state the loop is in, start with the stairs
while (state != 10){
for (int testing = 0; testing < 1000; testing++){
newx = getRand(1, xsize-1);
newy = getRand(1, ysize-2); //cheap bugfix, pulls down newy to 0<y<24, from 0<y<25
//System.out.println("x: " + newx + "\ty: " + newy);
ways = 4; //the lower the better
//check if we can reach the spot
if (getCell(newx, newy+1) == tileDirtFloor || getCell(newx, newy+1) == tileCorridor){
//north
if (getCell(newx, newy+1) != tileDoor)
ways--;
}
if (getCell(newx-1, newy) == tileDirtFloor || getCell(newx-1, newy) == tileCorridor){
//east
if (getCell(newx-1, newy) != tileDoor)
ways--;
}
if (getCell(newx, newy-1) == tileDirtFloor || getCell(newx, newy-1) == tileCorridor){
//south
if (getCell(newx, newy-1) != tileDoor)
ways--;
}
if (getCell(newx+1, newy) == tileDirtFloor || getCell(newx+1, newy) == tileCorridor){
//west
if (getCell(newx+1, newy) != tileDoor)
ways--;
}
if (state == 0){
if (ways == 0){
//we're in state 0, let's place a "upstairs" thing
setCell(newx, newy, tileUpStairs);
state = 1;
break;
}
}
else if (state == 1){
if (ways == 0){
//state 1, place a "downstairs"
setCell(newx, newy, tileDownStairs);
state = 10;
break;
}
}
}
}
//all done with the map generation, tell the user about it and finish
System.out.println(msgNumObjects + currentFeatures);
return true;
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
public static void main(String[] args){
//initial stuff used in making the map
int x = 80; int y = 25; int dungeon_objects = 0;
//convert a string to a int, if there's more then one arg
if (args.length >= 1)
dungeon_objects = Integer.parseInt(args[0]);
if (args.length >= 2)
x = Integer.parseInt(args[1]);
if (args.length >= 3)
y = Integer.parseInt(args[2]);
//create a new class of "dungen", so we can use all the goodies within it
dungen generator = new dungen();
//then we create a new dungeon map
if (generator.createDungeon(x, y, dungeon_objects)){
//always good to be able to see the results..
generator.showDungeon();
}
}
}