Bunny in the Water

Longteng Duan* · Guo Han* · Boxiang Rong*

(* Equal Contribution)

Slides (pdf, pptx) | Presentation | Demo

(Click to View our Demo Video)

Here we present our group project developed for the Physically-based Simulation in Computer Graphics course at ETH Zurich. Our work involved the implementation of several key features, including position-based fluids (PBF), collision handling of simple static rigid body, and generating diffuse materials such as spray, foam, and bubbles.

Presentation Video

(Click to View our Presentation Video)

Environment Setup

To run the real-time simulation, you need to install Taichi and Open3d. The Python version we use is 3.10.13, the Taichi version is taichi==1.6.0, and the Open3d version is open3d==0.17.0.

To run the rendering, you need to install splashsurf and Blender python API

Code Usage

Real-time Simulation

In this project, we built from scratch a Real-time Position-based Fluid Simulation pipeline, with advanced features like: static rigid body collision handling and diffuse particle generation (foam, spray, and bubbles). It is fully developed with the Taichi language and provides a GGUI interface for visualization. We also provide scripts to export the particle-based simulation results into mesh, and render the final scene with Blender Python APIs.

The simulation process can run at 25+FPS on RTX 3070 GPU.

If your computer does not have a GPU, please change line 15 in main.py to ti.init()

python main.py

Rendering

To prepare for rendering, follow these steps within the main.py file initially:

1. Set bake_mesh = True on line 117.
2. Specify the starting and ending frames for mesh creation on line 125.
3. Execute main.py until the output confirms the completion of mesh baking.

Afterward, execute python blender_render.py to commence image rendering. Please note that rendering the entire video sequence may require a considerable amount of time.

Reference

[1] Macklin, Miles, and Matthias Müller. "Position based fluids." ACM Transactions on Graphics (TOG) 32.4 (2013): 1-12.

[2] Ihmsen, Markus, et al. "Unified spray, foam and air bubbles for particle-based fluids." The Visual Computer 28 (2012): 669-677.

[3] J. Bender, D. Koschier, T. Kugelstadt and M. Weiler, "Turbulent Micropolar SPH Fluids with Foam," in IEEE Transactions on Visualization and Computer Graphics, vol. 25, no. 6, pp. 2284-2295, 1 June 2019, doi: 10.1109/TVCG.2018.2832080.

[4] Taichi Blog for Collision Handling: https://docs.taichi-lang.org/blog/acclerate-collision-detection-with-taichi

[5] Taichi PBF 2D Example by Ye Kuang: https://github.com/taichi-dev/taichi/blob/master/python/taichi/examples/simulation/pbf2d.py

[6] SPlisHSPlasH Library for Diffuse Particles Synthesis: https://github.com/InteractiveComputerGraphics/SPlisHSPlasH