WARNING

Code has many issues, and almost no comments. It's usage may require some fixes to run on different machine.

nbody

Barnes-Hut N-body simulation algorithm implementation.

Requirements

• OpenGL 3.3
• OpenMP 2.0
• freeglut
• glew
• glm

Brief introduction

This is implementation of classical Barnes-Hut N-body simulation algorithm.

All particles has mass of 1 kg, G constant increased for faster simulation.

Particles rendering uses point sprite technique. Shaders are used to change particle size according to distance from camera.

Sources

• nbody.cpp - main entry point, OpenGL rendering related stuff, and overall management.
• octree.hpp - octree implementation to be used in Barnes-Hut algorithm.
• resources.inl - shader releated stuff.

Implementation details

• Simulation processed with constant time step on each glutIdleFunc invocation. After each world update, screen redraw requested. (see nbody.cpp onIdle function)
• No optimization techniques are used to ease octree building, because time to build it from scratch in negligible in comparison with time spent in ocleaf_t::GetForceOnPoint function - 99% of simulation time program sits in ocleaf_t::GetForceOnPoint.

Configuration flags

There are some configuration flags in program, which affects simulation and its presentation:

• BRUTE_FORCE - when defined, simulation uses brute-force N^2 algorithm
• DEBUG_OCTREE - when defined, octree leaves with particles inside are drawn.
• WND_MODE - when defined, simulation runs in windowed mode, otherwise in fullscreen 1920x1080.
• USE_CUDA - when defined uses CUDA to run simulation using brute-force N^2 algorithm