[Innawoods] - Added mutable stream

[SandwichPie]

Summary

Content "Adds a mutable stream to the mapgen"

Purpose of change

Rivers are large and cumbersome, but most bodies of inland water are shallow and small. Especially in a wilderness mod like innawoods a stream/brook should be a point of interest where foliage and animals gather. It should add some visual interest and a respite from rolling fields and forests.

Describe the solution

Most map features are hardcoded, but I made this one take advantage of the mapgen mutables feature. This allows a lot of control over how the map elements generate and should be quick and easy to iterate over.

Mutables have several limitations however, making it not behave ideally in several situations.

• Firstly, you cannot select connections to anything other than specific hardcoded points, so I could not have it flow into river or pond tiles.
• Secondly, mutables seem to lack a feature to check if they are generating inside another mutable of the same type, so having two long streams close can cause map generation failures. Due to this I can only spawn one per overmap chunk.
• Mutables cannot spread across chunk boundries.
• Mutables cannot be set to terminate on certain conditions, like meeting a chunk boundry. Because of this the stream will prefer to deflect off chunk boundries instead of setting an end point.
• And I was unable to allow prior map generation to remain when a stream passes through, though I believe that was a failure on my part. This means that trees are destroyed when the stream passes through a forest.

That being said, I believe that since so much mapgen was removed from innawoods it can get quite repetitive, and the interest this adds back into to the maps makes up for the shortcomings of the implementation.

I do not believe that with mutables in this state that it would be appropiate to add larger mutable elements like this to be core game, but with a little more work I'm hopeful it would be very possible to replace the hardcoded map generation like rivers and roads.

Describe alternatives you've considered

• Hardcoded mapgen. It'd be a lot harder to implement, and we want less hardcoding and more JSON anyway.
• Not having streams.

Testing

Generated and ran across miles and miles of streams with slightly different settings. The monster spawn rate is probably too low, but it's better too low than too high. This can increased as needed.

The willingness for the stream to double back on itself could certainly be decresed, but I am happy with the current values. I don't want it to be too straightforward as this way it makes it a little more interesting.

Additional context

[github-actions]

Auto-requesting reviews from non-collaborators: @Light-Wave

[Procyonae]

A few thoughts, firstly big thumbs up for adding streams in general, I like the meandering and the way they're spawning on the overmap looks good ^^
Rivers are very much hardcoded but you could still make it so you have an end tile that can spawn over the bank tiles with nests to make it fit in (not saying this is easy and it could totally be added later).
I agree that this shouldn't be added to the base game but more bc I'd prefer river gen itself get reworked to be more sensible say by someone rezzing #38894 than by just adding streams and having an extra excuse not to touch river gen, while more innawood mapgen seems great in general due to the current lack of variety like you say.
While unhardcoding river with a mutable would potentially be possible, the chunk boundary stuff and lack of advanced logic mean they would look even worse than our current rivers so realistically we'd need multi tile wide connection support that I doubt will come any time remotely soon and would be a pain in the ass to make work. The only other way I can think of is having them be 1 tile wide connections but spawning them from and to the same point multiple times with no preference to spawn over themselves to make them seem wider and add a hack to make the boundaries wider, and I doubt that would look good either.
What issue(s) did you run into using fallback_predecessor to make it fit in with forests/swamps? I'm unhardcoding road and were quite surprised that I've managed to get away with fallback_predecessor there so I imagine it's possible to work around whatever hurdle you hit.
From you're description I'm not sure you realised special_locations isn't hardcoded in any way and there's no harm in adding extras if you want to try to some more fun stuff.
Just generally adding more nests in future and allowing them to cross trails with nests if you can get fallback_predecessor working (with a stepping stone or little z0 bridge for example) to add some variety would be cool.
I'm not suggesting this can't be merged in it's current state in any way though it already looks like a great addition just wanted to share my thoughts.

[SandwichPie]

Thank you Procyonae, I agree entirely with your suggestions.

My problem with 'fallback_predecessor' was me mistaking a flag as replacing it's function, but your comment let me find the relevant documentation. I've fixed the issue with the forests being overwrote now, I'll commit that change shortly after a couple more quick tests.

I know overmap specials are not hardcoded, but I wanted to keep this commit short becuase I have a habbit of making mods and never pushing them. I plan to followup this commit with some nested clay banks, cattails and better monster spawn rules. I'm not familiar with nesting yet though, so I thought it would be better to do that seperately.

I'm not sure how you are suggesting I connect the stream to a river using nesting though. I'm willing to look into it but I am at a loss with how that would be done right now. According to the docs, the connections option won't connect to rivers and I don't think there is a method to select certain overmaps if it detects a river bank. I'd be happy to be shown otherwise though.

And I also appreciate the surrounding context of the river generation problems, it was very interesting.

[Procyonae]

Nice, having it fit in with the terrain will make it really pretty ^-^

Small incremental PRs are defo sensible, excited to see where you take it :D

If you want any help with nesting (or any other mapping) at any point you can dm me on discord (or just mention me on the devcord) at the same username

Once this is merged I might have a play with the connecting to river thing, it might well not be possible anyway thinking about it bc river banks seem really trolly (I've tried to fix the seemingly easy issue #62544 multiple times and can't get anything to work) so I wouldn't worry about it for now

[Light-Wave]

I'm liking this a great deal. I agree with the previously made points that small incremental PRs are good here, and that it can stay in Innawood for now. Although it would be neat if it could enter mainline some day in the perhaps distant future.
I have been meaning to give Innawood players a way to more reliably get domestic animals, and this seems like a good opportunity to do so.
I'm 80% sure that a chance of 0.7 gets cast to an int and rounded down to 0 here.
I played around with it a little, and I think setting "GROUP_DOMESTIC" spawn chance to around 3 and "GROUP_FOREST" to maybe 25 would be more reasonable values.

[SandwichPie]

I did see a few instances of horses spawning, but that could have been from the wilderness spawn group so thanks for letting me know that can be a problem since that's a very important thing to note.

In regards to monster spawns, I'm already starting on a followup PR to address that. I'm remarkably displeased with how they are set up currently. I don't feel like the wildreness spawn group is weighted correctly for a stream and I want to be a lot more careful with how many monsters spawn for each species.

To address the rounding down issue, the followup PR may have only certain tiles have a chance to spawn domestic animals or I'll just try to weight it better with the custom spawn groups. The latter is probably the more sensible approach.

I'll change the spawn values in the current PR to what you suggeted for now though.

[NetSysFire]

This would fit the main game, too with some slight adjustments.

[Light-Wave]

This would fit the main game, too with some slight adjustments.

I absolutely support putting these into mainline once they have gotten some more improvements. If you want to work towards that goal, then feel free to 👍