Morphing Simulation: From Blender to Houdini — HHS2:E3

Houdini Houdono | S2E3 - Morph Simulation with Custom Falloff

Hey guys! Welcome to Houdini Houdono! Ronald here, and we’re diving into Season 2, Episode 3.

In this episode, I’ll show you how to use custom attributes to control your Vellum simulation—just like the effect you see on screen. This was a popular request on my Instagram, so if you’re curious about using custom attributes to drive simulations, this video is for you!

As always, I’m covering how to go from your native software to Houdini. Today, we’ll be importing Blender’s famous Suzanne model into Houdini and discussing some differences in the workflow. We’ll create a custom falloff attribute to drive both the simulation and the materials, giving you full control over how it all evolves.

Here’s what we’ll cover:
1. How to import models from Blender to Houdini.
2. Setting up a custom infection solver for falloff, using Pyro Source Spread.
3. Using the falloff attribute to drive the Vellum simulation and materials.

✨ Don’t forget! Head over to my Instagram post by 13 Oct 2024 and comment "Morph" to get the annotated working file for this setup. Can’t wait to see your renders! ✨

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Here are three important tips from this episode:

Using Custom Attributes to Control Simulations
Learn to create and manipulate custom attributes to drive simulations dynamically:

Use nodes like Pyro Source Spread to generate organic falloff patterns from a starting point.
Remap attributes (e.g., temperature) for different purposes such as simulation (sim_falloff) and shading (falloff).
Rest Length Scale for Dynamic Growth
In Vellum simulations, adjust the rest_length_scale property to control the growth of soft bodies. Remapping attributes allows you to achieve localized growth or deformation, making the simulation more interesting and visually engaging.

Efficient Import/Export Between Blender and Houdini
Understand the strengths and limitations of different file formats (e.g., OBJ, Alembic, FBX, and glTF) when transferring assets between Blender and Houdini. Address scale discrepancies by using transform nodes and match size to align imported geometry with Houdini’s units and ground plane.

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Instructor: Ronald Fong
Editor: Jasmine Seo