3D Fluid Simulation (C++/OpenGL)

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Description

A real-time 3D fluid simulation built to practice C++, graphics programming, and performance optimisation. The simulation implements Position Based Fluids (PBF) based on Macklin & Müller 2013.

Performance

The simulation was benchmarked using a custom profiler built into the binary, activated via the --benchmark flag. Each run measures per-phase wall-clock time across 2000 frames at a fixed timestep, logging raw per-frame timings to CSV for post-processing. The follwing results are true for running the benchmarks on an AMD Ryzen 9700X (8-core).

NOTE: GPU support is WIP

Benchmark Hardware

CPU	AMD Ryzen 7 9700X (8-core, 16-thread)
RAM	64GB DDR5 5600 MT/s (Dual Channel)
Compiler	MSVC
Build type	Release
OS	Windows

Scaling Behaviour

Per-Phase Breakdown (N=20,000)

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Controls

Keyboard

Key	Action
SPACE	Pause / Resume
→	Step one frame
R	Reset simulation
ESC	Toggle HUD

Mouse

Input	Action
Left click + drag	Pull particles
Right click + drag	Push particles
Shift + Left drag	Orbit camera
Ctrl + Left drag	Pan camera
Scroll Wheel	Zoom in / out

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Structure

src/
 ├── main.cpp              # OpenGL app + render loop
 ├── particles.*           # PBF simulation
 ├── particle_config.*     # Simulation parameters
 ├── linear_algebra.*      # Vec2 / Vec3 / Mat4 math
 ├── triangle_mesh.*       # Instanced quad mesh for particle rendering
 ├── grid.*                # Floor grid 
 ├── colors.h              # Particle colour ramp
 ├── cell.*                # Grid cell type
 ├── helpers.h             # Utility functions
 └── shaders/
 	  ├── grid_vertex.glsl
	  ├── grid_fragment.glsl
      ├── vertex.txt
      └── fragment.txt
benchmarks/
 ├── profiler.*            # Runtime profiler Util
 ├── run_benchmarks.ps1    # Build + run script (Windows)
 └── logs/                 # Benchmark CSV results

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Building

Linux (NixOS Recommended)

Debian-based

Depedencies

sudo apt-get install build-essential libglfw3-dev libgl1-mesa-dev

NixOs

In the project root, just run:

nix develop

That's it.

Configure and build

Quick build and run:

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --target fluid-sim

Extra Compilation Flags

If your device supports CUDA, but for some reason you would like to run the CPU-only version, you cand disable all CUDA execution with -DUSE_CUDA=OFF.

Run

./build/fluid-sim

Windows

Dependencies

Install vcpkg if you don't already have it:

cd C:\
git clone https://github.com/microsoft/vcpkg.git
cd vcpkg
.\bootstrap-vcpkg.bat
.\vcpkg install glfw3
.\vcpkg integrate install

Configure and build

cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=C:/vcpkg/scripts/buildsystems/vcpkg.cmake
cmake --build build --config Release

Run

.\build\Release\fluid-sim.exe

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Benchmarks

Windows:

.\benchmark\run_benchmarks.ps1

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Dependencies

• GLFW — windowing and input
• GLAD — OpenGL loader
• Dear ImGui — runtime HUD for parameter tuning

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References

• Macklin, M. & Müller, M. (2013). Position Based Fluids. ACM Transactions on Graphics, 32(4).
• Green, S. (2010). Particle Simulation using CUDA. NVIDIA Developer Technical Report.