This is the source code for the reference implementation for the paper "Efficient 2D Simulation on Moving 3D Surfaces".
(Morgenroth et al. 2020)
The code was tested on Windows with Houdini 17.5.x and 18.0.x. Binaries of our Plugin for Houdini 17.5 and 18 on Windows 10 can be found here: https://doi.org/10.5281/zenodo.4009208
This also works with the free apprentice version of Houdini. This can be downloaded at https://www.sidefx.com/tutorials/houdini-download-and-install-windows/
This code is provided under MIT License.
Tested with Visual Studio 2017 Use the provided visual studio project files. The cmake files are not yet updated.
Simply copy the according dll (Cappucino.dll) into your houdini dso folder. Typically located somewhere here: C:\Program Files\Side Effects Software\Houdini 1x.x.xxx\houdini\dso
Open one of the following files: buoyancy_flow.hipnc rotating_sphere.hipnc
You will find one Geometry node inside these files. On this geometry node, we added a parameter tab called SimAttributes. In this parameter tab the most important simulation attributes can be manipulated.
For both scenarios we set the parameter as presented in the paper, except the simulation resolution in the rotating_sphere example. There we chose a coarser one, for faster testing. You can adjust the resulution with the "simresolution" attribute.
Fluid attributes: Vorticity Changes the fluids vorticity. Note that this parameter is resolution dependent. When changing the sim resolution you need to adjust this parameter aswell. Velocity Diffusion The fluids dynamic viscosity constant. Coupling Friction Coupling parameter s_1 from the paper. Enlarges adhesion forces Coupling Curl Coupling parameter s_2 from the paper. Controls the strength of the Jacobian based coupling Coupling Noise With this parameter you can add some noise to the coupling, introducing more noise in the velocity field and therefore more fine scale details on the simulation.
Buoyancy attributes: Gravity Enables gravity to be scaled as described in the Boussinesq approximation. Heating Rate Strength of the temperature transfer from the outer constraints for the hot constraint. Cooling Rate Strength of the temperature transfer from the outer constraints for the cold constraint. Heat Dissipation Temperature change due to heat induced velocity divergence. Heat Diffusion Reduces relative temperature differences. Cool Temperature Lowest allowed temperature and temperature of the outer cooling constraint High Temperature Highest allowed temperature and temperature of the outer heat constraint Reference Temperature t_0 of the Boussinesq approximation. In areas of this temperature basically 0 gravity is present.
General Attributes: simresolution The VDB-Grid Resolution. Interpolation Method The CPM-Interpolation Method CPM Cells Width of the Narrowband Advection Scheme Integrator used for the Advection of the VDB fields Advection Substeps Number of advection substeps (Should in general be 1, for more details rather increase the substeps attribute) Substeps Number of Timesteps per Frame (Together with Houdini's $FPS attribute, it determines the simulation step size) Reset simulation Resets the simulation