Rainborg

Position-based Fluid Simulation.

Dependencies

This project has a few dependencies, which CMake will try to find:

• OpenGL
• GLFW
• GLM - Included
• RapidXML - Included
• TCLAP - Included
• libPNG - for image output
• Required for compilation on GPU:
  • CUDA
  • Thrust

Compilation

Once the dependencies are installed, simply run CMake on the build directly, like so:

> mkdir build
> cd build
> cmake ..

You can also configure CMake flags GPU_ENABLED and USE_PNG to enable CUDA compilation and PNG output respectively. For PNG output, make sure you have an empty directly pngs in your build directory.

> ccmake ..
# configure variables...

Once you've configured everything, run the generated Makefile:

> make

This should generate the executable ./testflow.

Running our code

Type ./testflow -h for a list of commands and their descriptions. Note that a scene file (such as the ones included in /assets) is required for the simulation to run.

Structure

• Main:
  • Parse command line arguments
  • Windows and display loop
  • Initialize things??
    • Load Files
    • Create scenes + data structures
• Parser:
  • Scene Parser
    • XML nodes:
    • fluid block positions, rest densities, colors, velocity, mass
      • fluid constants - viscosity, etc
    • fluid boundaries
    • camera position, rotation
    • timestep, timeframe
  • Mesh Parser
    • obj file, ply (or whatever)
    • translate to mesh boundary object triangles
• Scene:
  • Boundaries -> Mesh objects
  • FluidSim
    • Fluid Particles
      • mass, rest density (shared)
      • Position
      • Velocity
      • Color
    • Bounding box
    • FluidSim.step(dt, scene)
  • Forces (gravity)

Todo

• Rendering
  • Spheres (with lighting)
  • Optional import mesh, boundary
• Simulation
  • Do the thing
  • Go through FOSSSim, stepper
  • Boundary/collision detection handling (static rigid objects)
  • Serial
    • external forces (gravity)
    • predict position
    • find neighbors
    • jacobi iterator
      • constraint, lambda
      • s-correction
      • calculate delta-p
      • collision detection response
      • update positions
    • vorticity confinement
    • position update
  • Parallel
    • Buckets, arbitrary acceleration data structures
    • same thing...
  • Future

References

The algorithms in this project follow the following papers:

Miles Macklin, Matthias Muller, Position Based Fluids

Takahiro Harada, Seiichi Koshizuka, Yoichiro Kawaguchi, Smoothed Particle Hydrodynamics on GPUs

Techniques for CUDA-OpenGL interop functions are used from here: http://www.nvidia.com/content/gtc/documents/1055_gtc09.pdf

Additionally, an C++ OpenGL framework by Daniel Chappuis is modified for use in this project: https://github.com/DanielChappuis/opengl-framework

Finally, some XML parsing and Math utility functions are taken from FOSSSim, the codebase from Computer Animation W4167.