N-Body Physics Simulator (and Visualisator)

Installation by pip

python3 -mpip install git+git://github.com/N-BodyPhysicsSimulator/Main.git

To run

python3 -m nbp

How to contribute

1. Fork the project.
2. Write tests (TDD if possible [1 NL] [1 EN]) and write code.
3. Commit [1] [2] [3] (READ THOSE THREE LINKS, please) and push it to your forked repository.
4. Do a pull request. [1] [2] [3]
5. You will receive a code review soon.
6. If quality of code is high enough and Code Coverage is higher than before [1] [2], code will be merged. Otherwise: go to step 7.
7. After we wrote a code review, you could improve your code according to our suggestions. Please, improve your code.
8. Go to step 4.

How to run from source

For running the simulator, Python 3.5.x or higher is required.

Not tested on Mac OS X/macOS or Microsoft Windows.

Linux / Mac OS X

Installation from source

1. Run make install-requirements-app
2. Run tests and make sure there aren't any failing tests.

Run tests

1. Install bats
2. Run make install-requirements-dev
3. Run make test

Run application

• There are a few Input Providers, such as csv or json which you can use to import BodyStates (note: the csv Input Provider only imports one state. This is a required argument.
• There are as well Output Writers, to do something with the input. Like the ws, http and csv Output Writer. Required option.
• Delta Time is a required option as well. This is the change of time between two states.

For example: run python3 -m nbp

usage: nbp [-h] --inputprovider ip --outputwriter outputwriter
                  [outputwriter ...] --delta-time seconds
                  [--modifier [modifiers [modifiers ...]]]
                  [--max-ticks ticks | --max-time seconds]
nbp: error: the following arguments are required: --inputprovider/-i, --outputwriter/-o, --delta-time/-dt

• max-ticks is used to exit the simulator after a specific amount of ticks
• max-time is used to exit the simulator after a specific amount of time (see delta-time)
• modifier is used to modify data from the Input Provider before passing it to the Output Writers. You could use calculation to calculate new data.

You could run python3 -m nbp --inputprovider json -o ws -dt 10

[...]
nbp: error: the following arguments are required: --input-file, --ws-port

The json Input Provider requires parameter --input-file with a path to the JSON file and the ws Output Writer requires --ws-port with a port for the WebSocket server to 1listen on.

Let's run python3 -m nbp --inputprovider json -o ws -dt 10 --input-file /home/<user>/input.json --ws-port 8080

The simulator will now load the states from the JSON-file, but it won't calculate anything at all. We can use --modifier to make it calculate data.

Run command python3 -m nbp --inputprovider json -o ws -dt 10 --input-file /home/<user>/input.json --ws-port 8080 --modifier calculation --max-ticks 10000

The simulator will now import the states from the JSON-file, and it output all states from the JSON-file to the OutputWriters. On the last state, the CalculationModifier will start to calculate. Simulator will quit after 10000 states because of the --max-ticks option.

You can use multiple OutputWriters at once: python3 -m nbp --inputprovider json --outputwriter json csv ws -dt 10 --input-file /home/<user>/input.json --json-output-file /home/<user>/output.json --csv-output-path /home/<user>/csv-output --ws-port 8080

Goals

General

• 100% code coverage
• Reading and writing results to a .CSV-file Excel-file (Excel will be used because of the possibility of multiple sheets/tabs. A different program will be created to export Pickle-�files to Excel files.)
• Reading start-values of bodies from JSON or and CSV
• Reading and writing data from a file (JSON)

Conversions

• Import and export from/to Pickle with Base64

Simulator

• Optimizing code for CPU (use of async-code, multiple threads?)
• Optimizing code for GPU. GPU's are really good in doing many simple functions. (We could use ArrayFire, OpenCL or CUDA)
• The possibility to theoretically calculate infinite bodies
• Changing the delta time (change in time) based on the distance of bodies to eachother
• Spaceship: a body with the possibility to change speed depending on commands

Visualisator

• Showing the data of the simulator on xy-, yz- and xz-diagrams (2D)
• Changeable virtual time
• Determining the middle of the display
• Showing the data of the simulator in three dimensions (xyz, 3D)