lemontheme / rct

Creating cool coasters for Roller Coaster Tycoon

What is it?

The goal of the project is to generate cool looking roller coasters via a genetic algorithm. Something like this:

What's been done so far?

Here's what we have:

• A list of all of the track pieces used in the game and metadata about them (elevation change, left/right etc)

• A way to read rides from the game, and serialize track data generated outside the game to be used in the game.

• Some library functions to make vector math easier (e.g. after this track piece, what is the new location and orientation of the car?)

• A basic genetic algorithm with mutation, selection, crossover, and a fitness function.

• Results of every experiment are recorded to disk. There's a server you can use to view the results of experiments, and which has an easy "convert to TD6" button.

What needs to get done?

• Tracks currently don't load in the game because the collision detection algorithm isn't correct. The experiment runner will report 0 collisions, but tracks will fail to load because there is actually a collision. You can verify this by printing out the individual track pieces, starting the game and attempting to rebuild the track. I'm not sure how best to fix this than by attempting to fix individual instances as they pop up.

• The fitness function does not have enough inputs. Specifically, it currently checks whether a track is a complete loop and doesn't collide with itself. It could check:

  • Excitement. The easiest heuristic for excitement is what's used to compute excitement in the game Roller Coaster Tycoon 2; would take into account the number of drops, the speed, G forces etc.

  • Physics - whether the car can make it around the track.

  • G forces

  • More ! Scenery, etc, you name it.

• The fitness function is currently very slow. Need to run the code with pprof to figure out what exactly is slow, and then improve its performance. The existing code is extremely dumb - it runs sequentially in one thread. Likely there are some easy improvements to be made by using more than one CPU at a time.

• The server can display track data but the camera is out of position, so sometimes the track is not visible. It would be really neat to be able to better see track data outside of the game.

• The genetic algorithm will probably need some tweaking once the fitness function has more parameters. This is hard to evaluate right now.

Installation

You need to have Go installed (I use Go 1.5, but it should work with any version). Once you do that, run:

go get github.com/kevinburke/rct

Once you've downloaded the source code, run make install to ensure all third party dependencies are downloaded.

Check you have a valid install by running: make test. You should get output like this:

go test -timeout 1s \
		./bits/... \
		./genetic/... \
		./geo/... \
		./image/... \
		./rle/... \
		./server/... \
		./td6/... \
		./tracks/...
?   	github.com/kevinburke/rct/bits	[no test files]
ok  	github.com/kevinburke/rct/genetic	0.011s
?   	github.com/kevinburke/rct/genetic/get_latest_track	[no test files]
?   	github.com/kevinburke/rct/genetic/get_old_experiments	[no test files]
?   	github.com/kevinburke/rct/genetic/run_experiment	[no test files]
ok  	github.com/kevinburke/rct/geo	0.010s
?   	github.com/kevinburke/rct/image	[no test files]
?   	github.com/kevinburke/rct/image/above_runner	[no test files]
ok  	github.com/kevinburke/rct/rle	0.011s
?   	github.com/kevinburke/rct/rle/decode_td6	[no test files]
?   	github.com/kevinburke/rct/rle/encode_td6	[no test files]
?   	github.com/kevinburke/rct/server	[no test files]
ok  	github.com/kevinburke/rct/td6	0.010s
ok  	github.com/kevinburke/rct/tracks	0.008s
?   	github.com/kevinburke/rct/tracks/branch_factor	[no test files]

(Some of the packages don't have tests unfortunately)

Running experiments

You should be able to run new experiments by typing make experiment. This will place new experiments in subdirectories in /usr/local/rct. It should also give output in the console that looks like this:

run_experiment --package-root ~/code/go/src/github.com/kevinburke/rct
Experiment exp_ddc75161-8370-4ead-aa76-71ebdb59f1d5
======================================
Iteration 0: 500 members, best member iter_d667e484-ef33-40cd-ad30-52d5e6a90036 has score 1680000, median 1527000, worst has score 172000
Iteration 1: 500 members, best member iter_d667e484-ef33-40cd-ad30-52d5e6a90036 has score 1680000, median 1517000, worst has score 172000
Iteration 2: 500 members, best member iter_7f34d78b-4e1e-4be2-b17f-d46b51fa065d has score 1672000, median 1443000, worst has score 172000
Iteration 3: 500 members, best member iter_9cbedb01-9447-40b0-9973-aeb4af67faf5 has score 1672000, median 1443000, worst has score 172000
Iteration 4: 500 members, best member iter_9cbedb01-9447-40b0-9973-aeb4af67faf5 has score 1672000, median 1554000, worst has score 172000

Start the server by running make serve and you should be able to view your experiment by browsing at localhost:8080.

Package Layout

There are a few different packages in here.

• genetic - implementation of a genetic algorithm to build coasters. Hopefully this can become a better implementation than just RCT specific but there are other genetic algorithm implementations for Go at the moment, so this is not a huge priority.

• exe_reader - Reads the RCT2 exe and prints out metadata about track segments.

• rle - deals with run length encoding of RCT files (so they can be read/written in the game). More info in the specific package.

• td6 - a td6 file is a RCT ride file. This package encodes/decodes raw TD6 file data into Go structs.

• image/* - turns track data into pretty PNG files. Hasn't been touched in a while and only ever implemented a 2d viewer. Decided to try using three.js instead, for greater compatibility and access to a better feature set.

• bits - convenience functions for dealing with bits.

• wip/* - various "discovery" scripts that read bytes from openrct2.exe dealing with track data. Shouldn't need to touch this, we might need to clean it up at some point because Go complains about the number of main files in this folder.

Donating

Donations free up time to make improvements to the project, and respond to bug reports. You can send donations via Paypal's "Send Money" feature to [email protected]. Donations are not tax deductible in the USA.