chipmunkcore

chipmunkcore is a low-level wrapper around the Chipmunk2d rigid body physics simulation library.

chipmunkcore is just the simulator. To actually render the positions of bodies in the simulation you’ll need to use ggplot2, cairocore or something else

Read the online documentation for chipmunkcore here

Regular users will probably want to use the higher level wrapper chipmunkbasic

Chipmunk2d

  • Chipmunk2d is a C library for simulating rigid body physics
  • chipmunkcore is a very low-level wrapper around the C library, providing 1-to-1 mapping between R functions and the core C library
  • chipmunkbasic provides a nicer wrapper around chipmunkcore

System Pre-requisites - chipmunk2d C library

You’ll need to install the Chipmunk2d library on your system.

Click to show instructions for macOS I only know how to do this on macOS where you can do

brew install chipmunk

You may also need to update/install your xcode tools - see here

Click to show instructions for ubuntu - method 1

Thanks to tylermorganwall for the following instructions

I spun up an RStudio AMI on AWS to try and install chipmunkcore and was successful. Here’s my instructions:

First we need to install cmake if it’s not already installed, along with some other pre-reqs:


sudo apt install cmake
sudo apt-get install xorg-dev

Now we install the Chipmunk2D library:

git clone https://github.com/slembcke/Chipmunk2D
cd Chipmunk2D
cmake .
make

And finally, symlink the header files and shared object library so R can find it during installation. The path /home/rstudio/Chipmunk2D will be different depending on where you installed the Chipmunk2D folder.

sudo ln -s /home/rstudio/Chipmunk2D/include/chipmunk /usr/share/R/include/chipmunk
sudo ln -s /home/rstudio/Chipmunk2D/src/libchipmunk.so /usr/lib/R/lib/libchipmunk.so

Click to show instructions for Linux (verified on Ubuntu 18.04 LTS) - Method 2

Thanks to Henrik Bengtsson for the following instructions.

These instructions should work on most Linux systems.

Following the instructions on https://github.com/slembcke/Chipmunk2D:

Before we can install the software, we need to build it:

curl -L -O https://github.com/slembcke/Chipmunk2D/archive/Chipmunk-7.0.3.tar.gz
tar xf Chipmunk-7.0.3.tar.gz
cd Chipmunk2D-Chipmunk-7.0.3
cmake .
make

Now we can install it. If we have admin rights, we can install it system-wide as:

sudo make install

You’re done!

If we only have non-privileged user rights on the system, then sudo make install will give an error. Instead, we have to install to a folder where we have write permissions. This can be done by specifying the CMake-specific environment variable DESTDIR:

mkdir -p "$HOME/software/Chipmunk-7.0.3"
make DESTDIR="$HOME/software/Chipmunk-7.0.3" install

For other software to be able to compile toward Chipmunk2D, we need to update a few standard environment variable:

export CPATH="$HOME/software/Chipmunk-7.0.3/usr/local/include:${CPATH}"
export LIBRARY_PATH="$HOME/software/Chipmunk-7.0.3/usr/local/lib:${LIBRARY_PATH}"

If you got this far, you should be able to install chipmunkcore in R:

# install.package('remotes')
remotes::install_github('coolbutuseless/chipmunkcore')

Now, in order for compiled software to find the Chipmunk2D library files when running, we also need to add:

export LD_LIBRARY_PATH="$HOME/software/Chipmunk-7.0.3/usr/local/lib:${LD_LIBRARY_PATH}"

If you got, you will be able to use the chipmunkcore package:

> library(chipmunkcore)
>

If you get:

> library(chipmunkcore)
Error: package or namespace load failed for 'chipmunkcore' in dyn.load(file, DLLpath = DLLpath, ...):
 unable to load shared object '/home/alice/R/x86_64-pc-linux-gnu-library/4.0-custom/chipmunkcore/libs/chipmunkcore.so':
libchipmunk.so.7: cannot open shared object file: No such file or directory

then LD_LIBRARY_PATH is either not set or set incorrect.

Tips: Append the above export ... lines to your ~/.bashrc so set them automatically.

No windows instructions available for C library installation - Can you help?

If you know how to install the Chipmunk2d C library on Windows, and subsequently compile this package, please let me know by filing an issue, or pinging me on twitter. Thanks!

Installation

After installing the Chipmunk2d C library, you can install this package from GitHub with:

# install.package('remotes')
remotes::install_github('coolbutuseless/chipmunkcore')

ToDo

  • Add constraints
  • Expose more of the underlying C library

Galton Board

For full code, see the vignette in chipmunkbasic

Acknowledgements

  • R Core for developing and maintaining the language.
  • CRAN maintainers, for patiently shepherding packages onto CRAN and maintaining the repository