In the previous post in this series we saw how terrain is generated and how the procgen system decides each area in the world will be connected, which controls the progression of the player through the game. In this post I explain how the contents of those distinct areas are filled. As mentioned earlier, while Binding of Isaac and Spelunky use hand-designed templates to generate this content, Lenna’s Inception takes a different approach.

Spatially-aware room content generation

This part of the procgen system is aware of the spatial relationships between objects. By formalizing (making strict machine-readable rules) the constraints each kind of tile places on its neighbors, the system can choose where to place randomized objects without breaking the game. As an example rule, a cracked rock requires floor next to it so that a bomb can be placed there. If it was placed next to some water, the bomb would sink and not blow up the rock. The system understands this could prevent the player from progressing and will not by default put water next to cracked rocks.

…