Liquid Simulation in Houdini

RBD & FLIP Interactions with Stavros Sofianos

Simulate milk pouring into a bowl of cereal to learn the art of interacting with Rigid Body Dynamic objects and FLIP Fluid Particles. This 3.5-hour workshop by Stavros Sofianos will teach you how to craft a dynamic, art-directable splash effect, filling the bowl with milk and allowing your cereal pieces to float. This tutorial is created for intermediate-level artists with a basic understanding of Houdini. 

Stavros begins by creating various layers of cereal and placing them in a simple yet effective way that will allow you to create a pleasing splash interaction later using the FLIP solver. You’ll also explore a Voronoi fracture technique to correctly create proxies that can be used in an RBD simulation to generate the initial state of the cereal in the bowl.

You will discover how to reconnect the proxies back to the original geometries, how to create the emitters for the FLIP simulation, how to master a custom stick field technique so you can control the stickiness of the milk on the bowl and on the cereal, and you’ll learn how to efficiently set up an RBD and FLIP solver together to interact with each other.

This workshop also details how to create our own custom mesh for the FLIP simulation, shows a technique for generating wet maps, and covers Stavros’s shading and rendering techniques using the Arnold renderer.

Project files provided with this workshop include two bowl geometry files (one in Alembic and one in FBX format) and the Houdini file with the setup that Stavros created for this workshop. Links to the models and free assets used are also provided.