Archives For Simulation

Adding vdb vel fields to FLIP

November 16, 2019

Using vel fields to control the flow of FLIP sims is quite the handy trick, and using the new source volume nodes set to “pull” allows you to add in your vel fields without them looking like they are taking over the sim completely. Here’s a hip file too: directable_FLIP.hiplc

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I’ve been having a serious look at using spheres and also boxes to represent the collision
shape in bullet simulations. Spheres are great in that you can rely on the geometry to not get caught and hang on to each other. Boxes offer a nicer settling motion in certain setups too. The main reason I wanted to look at it, was to avoid always needing to use glue constraints. Sometimes I want a nice quick voronoi fracture that uses the clustering option, and this yields shitty collision approximations with convex hulls.

Enter vdb sphere packing! It allows me to fill the wacky geometry shapes and use those as colliders. I just save out my points, and transform the original pieces. Voila!

vdb_sphere_packing

[vimeo 131941068 w=660 h=281]

FLIP Variable Viscosity

January 1, 2015

Still needs work for the surface snow that would stick. Yes yes, the ray traced SSS is fucked as well.