Your browser (Internet Explorer 6) is out of date. It has known security flaws and may not display all features of this and other websites. Learn how to update your browser.
X
Images

Procedurally Creating the Interior of a Building

Procedurally Creating the Interior of a Building

Over the last couple of weeks I have been working on generating the inside of buildings. The buildings in the game need to have rooms and interiors. Every building should be filled with possibilities, not just a handful. I’ve been reading many, many, many articles, watching loads of videos and trying to digest as much knowledge on the subject. I came to realise this problem was not much different from dungeon generation in Rogue-like games. Each floor of these buildings is like a level in a dungeon, just going up instead of down. Roguebasin became a very useful resource and will continue to be as this project continues.

First up was to tackle room generation. Watching that Subversion video over and over again, I came to realise they were subdividing spaces and then deleting walls somewhat arbitrary. It created very nice rooms. The common theme I keep seeing in procedural content generation is that simplicity allows for complexity. I settled on a simple Binary Space Partitioning to create the basic rooms. Using the structural pillars of the building to draw a base room unit, I would divide and divide again until it was either too small the divide further, or it randomly decided to stop. The building core would have to be accounted for so I started to four super rooms that surrounded it. These super rooms contained all the room units on the floor that would then be split to create something like the above layout.

Next I would generate all the walls that partition these rooms. Each wall had two points that defined it and these points will come in handy later. I then iterated through the walls and deleted a percentage of them to give some larger, interesting rooms and cleaning up loose walls after.

Next up was calculating the depth of these rooms from the core. The above image displays this, starting at white for the core. It goes red through to violet, nearest to farthest respectively. The depth will be handy for further generation and later on when assigning goals within the game.

I needed to generate corridors next. These will link up most, but not all rooms directly to the core. Initially, I attempted a really simple algorithm. I looped through all the rooms converting one of its free walls into a corridor. I avoided small rooms that I had labeled as cupboards/store rooms and any walls touching the external parts of the building were ignored. I then checked if there were any obvious gaps in the corridors and plugged those. I ended up with the above which was adequate for my purposes until I tested it on some other seeds. It fell short too often so I ditched it.

Instead I used the basic Dijkstra Map process over all the wall points. Starting from the outside walls, each corridor would attempt to work it’s way back to the core choosing the shortest path. This was more than adequate and gave rise to some very interesting floor plans. Finally, I looped through the rooms from the core, adding doors into walls and corridors until every room became accessible. The above is a final layout with geometry created.

There are some further additions I need to look into. I can definitely improvement the corridor design, like backtracking and selecting a different path if it can’t get close to the core. Corridors should prioritise larger rooms. There could be less doors or maybe slightly smarter door placement. For now – this will do!