CUDA FFT Ocean Simulation

Real-time ocean surface simulation running entirely on the GPU, using the Inverse Fast Fourier Transform (IFFT) with the JONSWAP spectrum for wave energy distribution — the same approach used in AAA game engines like those behind Sea of Thieves and Assassin's Creed: Black Flag.

Overview

The simulation generates a statistically realistic ocean surface by:

1. Building a frequency-domain spectrum using the JONSWAP model based on wind speed, fetch length, and sea state
2. Evolving it over time using wave dispersion relations
3. Running an IFFT on the GPU via cuFFT to recover the spatial surface each frame
4. Rendering the result in real-time using OpenGL with CUDA/GL interop

An ImGui debug panel allows live tuning of wind parameters, wave amplitude, and choppiness without restarting.

Tech Stack

• CUDA + cuFFT — GPU compute and FFT
• OpenGL + GLEW — real-time rendering
• GLFW — windowing
• GLM — math
• ImGui + ImPlot — debug UI

Dependencies

• CUDA Toolkit (tested on CUDA 12.x)
• GLFW 3
• GLEW
• OpenGL

External dependencies (imgui, glfw, glm) are in external/.

Build

# Build the project
make

Run

make run
# or directly:
./output/fft_program

References

• Hasselmann et al., Measurements of Wind-Wave Growth and Swell Decay during the Joint North Sea Wave Project (JONSWAP), 1973
• J. Tessendorf, Simulating Ocean Water, SIGGRAPH 2001 Course Notes
• FFT-Ocean by gasgiant
• Water by GarrettGunnell
• Video reference 1
• Video reference 2