Falling Sand

Falling Sand Simulation using SDL3 GPU with compute shaders

Building

Windows

Install the Vulkan SDK for glslc

git clone https://github.com/jsoulier/falling_sand --recurse-submodules
cd falling_sand
mkdir build
cd build
cmake ..
cmake --build . --parallel 8 --config Release
cd bin
./falling_sand.exe

Linux

git clone https://github.com/jsoulier/falling_sand --recurse-submodules
cd falling_sand
mkdir build
cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
cmake --build . --parallel 8
cd bin
./falling_sand

Algorithm

Note

The algorithm is extremely inefficient. It brute-force calculates everything each frame. That said, I can easily get 16 million particles (4000x4000) simulating at 60 fps on my RTX 4050

1. Clear the write texture
2. Divide the area into 3x3 cells (so that there's no race conditions)
3. Dispatch 9 times (for each cell within the 3x3 cells) and simulate each particle
4. Swap the read and write texture
5. Apply a blur (not really a blur) to fill in gaps between particles

References

• Youtube Video by MARF