Starflood is an open-source SPH and N-body code(s) written in C/C++.

Features

• 3D Smoothed-particle hydrodynamics (SPH)
• 3D O(N*log(N))-complexity tree gravity solver using the Barnes-Hut algorithm
• Decently optimized low-level C/C++ code with high-level parallelism via OpenMP
• Simultaneous simulation and rendering
• Performance profiling using omp_get_wtime for double-precision timing (a little less granularity than a nanosecond after 6 months uptime)

Planned

• Combine all sources into one clean, configurable, SPH/N-body code
• Optimize SPH neighbor search to be better than O(N²)
• Multipole Barnes-Hut or Fast-Multipole Method
• Ability to save/load simulation data and render it afterwards
• Ability to load pre-generated initial conditions
• Heterogenous Compute Offloading (development is currently made difficult due to a lack of compiler packages with build support on Arch Linux, and NVIDIA's HPC SDK requires AVX so that's out of the question...) I now have access to an Intel Core i7-3770K, which has AVX (something which NVIDIA's HPC SDK unfortunately requires)
• Volumetrically rendering SPH particles for eye candy visualization
• A more standardized build system such as CMake
• Distributed computing (Using Open MPI or something)

Credits

• Philip Mocz's Python SPH Guide
  • https://github.com/pmocz/sph-python
  • Used as a reference for the SPH algorithm, although the numpy syntax was a little hard to decipher...
• stb
  • https://github.com/nothings/stb
  • stb_image.h and stb_image_write.h headers for image read/write
• Jeffrey Heer's article The Barnes-Hut Approximation: Efficient computation of N-body forces
  • https://jheer.github.io/barnes-hut/

Running Starflood

Starflood does not require any method of installation. It's up to the user to manually choose where they want the repository and build it.

Getting the Source Code

First, navigate to a place you like to keep your repositories. For example, I like to keep mine in ~/source.

cd <folder you want the starflood repo in>

Next, clone the Starflood repository.

git clone https://github.com/Zi7ar21/starflood.git

Next, enter the repository.

cd starflood

Configuration

Starflood is still in its infancy, as such, all of modification happens through modifying source code. Don't fear however, as I try to keep parameters as #defines near the top of the source files.

Mounting a tmpfs (Optional)

Starflood renders timesteps and saves the frames to the disk, before they get rendered by ffmpeg as a video file. Since you may be rendering a lot of frames, it is desirable to render (2g means a tmpfs with a size of 2 GiB):

sudo mount -t tmpfs -o size=2g tmpfs out

This will make running Starflood faster as it doesn't wait for images to be written to the disk. My condolences if your sysadmin does not let you mount tmpfss. I plan on adding the ability to defer writing images or writing them in a separate thread, but for now this is not implemented.

Building from Source

Starflood uses a custom shell script for compilation. While I would be flattered if you trust me, I encourage you to never run shell scripts without at least inspecting them first.

In the root of the repository there is a shell script test.sh, which will automatically build Starflood, clean a previous render (if one exists), and render the resulting frames with ffmpeg. However, you can execute each of these steps individually if you so wish. build.sh builds starflood with g++, and encode.sh renders it as a .mp4.