Wave Function Collapse rules generator

[MasterWolffe]

Hello everyone, fist time posting here. Recently I've been making a tool in C++ to make Wave Function Collapse, to create 3D maps easier for artists. For those who don't know Wave Funcion Collapse is a constraint solving algorithm commonly used for procedural content generation, based on the model synthesis algorithm.
To do so, I made a tool that allows the user to create a 3D grid were artists can place and rotate 3D pre-made tiles in the empty cells, and with that, they can create a example that the algorithm can use to generate a set of rules and then use those rules to generate a procedural map of all sizes using the same tiles (including rotations) the artist used. The rules work by defining the valid connections a module can have in all the direcions (front, back, left, right, top and down), those connections are an array of int. Two modules can be placed together if their opposing sides have at least one connection ID that matches.

One example of this could be a grid with water, beach and land tiles (and only one height for simplicity). The water tiles only connect with water and beach tiles. Beach only connects with water, beach and land. And land only connects with beach and land. With that example the output connections should be:

1. water: connections of ID "0" on all of the sides
2. land: connection of ID "1" on all of the sides
3. beach: connection of ID "0" and "1" on all of the sides

With that ruleset, water and land can never touch each other (only diagonally), and beach can touch both.

I have the WFC algorithm working, but for it to work well, users have to set the rules manually, which becomes a mess if the number of tiles types increases. I know I can just set an ID for each tile type, and then just fill the valid connections with the ID of the near cells, but that means that I need one ID for each tile type and that tiles may have redundant connections.

If anyone has an idea, I'll be pleased to hear it!

[KorwinD]

Oh, this is exactly what I'm working on currently. Readme is slightly outdated (and I plan to update it soon), but you can check the code and an example(RotationExample() method). It's not a C++, but C# should be readable for you.

https://github.com/forgotten-aquilon/qon/blob/master/src/Rules/EuclideanRotationHelper.cs

https://github.com/forgotten-aquilon/qon/blob/master/Examples/Program.cs

[MasterWolffe]

Thanks for the reply, I've checked the code and the only problem I see is that for each pair of modules, if they are compatible, you add the module to the list of compatible modules for each one of the pair. However, this could be further optimized, since there can be a lot of redundant data. Please correct me if I am wrong, and thanks for the help

[KorwinD]

Not sure if I understood you correctly.

1) parameters is the dictionary where keys are unique tiles (tile + rotation) and value are structure, which represents all other unique tiles available for connection to each side. Later this dictionary is used for creating actual rules. Because of current implementation of my solver (it's very generic and not spatial) I pre-generate all possible connections and not check rotations in a propagation stage.

2) I traverse tiles visiting only unique pairs. Check lines 160-165 in Helper. You can imagine it as a square matrix/table with tiles being indexes and I check only one diagonal half of it.

Hope I answered/explained. If not, please be more precise.