The last two weeks have been relatively light on game work. The main things have been: 

• Research into setting up an LLC (i.e making this a “legit business”)
• Making the settings menu
• Adding smoke to the steam engine

The LLC stuff may be a future dev diary, since I haven't finished yet, but I'll discuss a bit about the other two. 

Settings - I'm not entirely sure what to put here at the moment, apart from volume and a fullscreen toggle. I feel like there should be more, but at the moment I'm drawing a bit of a blank. Volume is separated between sounds and music - if left at default values, the music is very loud and overpowering. For screen resolution, Godot handles the scaling to the actual resolution, so a manual setting isn't really needed. 

Smoke - so I had been putting this graphical detail off, but this was actually a neat little project. So I've been using Krishna Palacio's Minifantasy art to build a lot of Iron Village’s graphics, but this time I've gone with Jamie Brownhill’s World of Solaria set. The smoke was originally designed for a house chimney, with the whole column of smoke in one image. Luckily the individual “puffs” of smoke were mostly separate, so I could slice it up into a sprite sheet for the whole lifecycle of one puff.

Next up is actually animating the flume of smoke. I might have been able to get away with just having one sprite representing the whole thing, but this is a key detail of the game so I wanted to do it “properly”. The main mechanics of animating the flume are as follows: 

1. At a specified time interval, spawn a puff of smoke at the top of the smokestack. Make sure it is not a child node of the train - that is, its movement must no longer be completely linked with the train itself. 
2. Each puff keeps track of its own velocity, which starts with a y component moving slowly up and an x component starting at the speed of the train. That way, at least initially, it'll move along with the train, but just go straight up if it stopped. 
3. Each puff will slowly decelerate. Air resistance slows it down as it disperses through the rest of the air. 
4. Over the lifetime of the puff, it slowly expands and then shrinks, to represent it expanding and fading away. 
5. On top of all that, respond to changes in the in-game clock: stop the animation when paused, speed it up during 2x or 4x speed.
6. Remove the puff once the animation is done.

All of these are fairly simple by themselves, and get a little more complicated when put together, but the result is a really nice animation that looks smooth too. It just takes a bit of math to roughly approximate the physics.

Anyway, somehow I wrote multiple paragraphs about “relatively little game work”, so I'll leave you with the video of all of this in action: