Train yards

I've been struggling to work out the best way to modify train carriages - what interaction for adding new carriages will feel correct.

For the time being, I've opted for a temporary separate structure called a 'train yard' which is effectively a variant of a station.

When a train is within one of these, the UI shown is that of being able to add carriages from your inventory to the actual layout of the train

There are a lot of things about this that aren't quite correct or feel strange - for example being able to carry around an new entire train carriage in your inventory. But this setup - even if it's temporary - has finally opened up the ability to earn money, purchase new carriages, add them to the train and use them to carry more or different cargo

It's still very rough, and although they are usable for cargo, the display of the newly added carriages in the world is junk right now (they tend to get stuck and don't persist in save games properly).

I've also ended up with an awkward situation where I have both a data model for what is currently in the train (its inventory) and the model of what carriages are on the actual visual for the train. This made sense at the beginning, but seems like a situation I need to change before it gets out of hand (synchronising two structures intended to mirror each other always goes south very quickly).

Lots to fix in the shortterm and also quite a few longer term questions to mull over:

• Should carriages be carry-able as items in the player inventory like this?
• If not, how do they get put onto the train? If there is an NPC interaction to buy/build them, how do we avoid the situation where you have to ping pong from one location to another to see the 'result'? Or should the NPC be outside controlling the train yard? (and the carriages don't come from your inventory at all?)

Need to fix it up and see what happens...