gl-pic-fluid

Realtime 3D particle-in-cell fluid simulation

Based on Robert Bridson's Fluid Simulation for Computer Graphics, 2nd ed.

Implements NVidia's "Screen Space Fluid Rendering for Games".

Video Demo

Requirements

• OpenGL >= 4.3
• cmake >= 3.10
• C++ compiler for version >= 17

Building

1. git submodule update --init --recursive
2. mkdir build
3. cd build
4. cmake ..
5. Use generated build system

Running

1. cd build
2. bin/fluid

Controls:

• Left click and drag to interact with fluid
• Right click and drag to rotate the view
• space - play/pause
• s - step
• r - reset
• f - toggle screen space fluid rendering
• p - toggle particle visibility (for viewing grid)
• PIC/FLIP blending controls
  • home - set FLIP 0.9
  • end - set FLIP 0.0 (PIC)
  • page up - increase FLIP
  • page down - decrease FLIP
• Grid visualization controls
  • g - toggle grid visualization
  • 1 - cell type
  • 2 - velocity
  • 3 - divergence
  • 4 - pressure solver A coefficients
  • 5 - pressure

Known Bugs

• There is a lingering boundary condition bug which causes fluid to stick to positive direction walls.
  • The stickiness is patched in the pressure update shader, but a bias in the fluid pressures remains.
• If fluid gathers in the +XYZ corner of the cube, it can cause the simulation to explode. I expect that this is related to or is a result of the previous bug.
  • Press r to restart the simulation if this happens

Development

• Simulation code is split across src/Fluid.hpp and *.cs.glsl shaders in shader/
• Make sure to list new source files in CMakeLists.txt!