Houdini 21 Splash Screen - Swirling Marbles

The splash screen for Houdini 21, made while I was at SideFX. It started as a short experiment, Swirling Marbles, built in a little under two weeks, and became the image that opens the software.

The question behind it was how to art direct something that moves on its own. Instead of keyframing shapes, I designed how they behave: a 2D Flow Solver running on the GPU moves pixels the way a fluid would, so every change could be judged almost immediately. In that system velocity becomes direction, feedback becomes memory, because each frame carries into the next, and dissipation becomes fade.

The motion is shaped by influence rather than control. Forces and noise add turbulence; a 3D surface, turned into a height map and its gradient, gives a direction field that follows the form, so the geometry steers the flow. Once the motion felt right, the velocity image became a 3D volume that advects particles and Vellum grains, and the same flow data drives their colour, reflection and refraction in Karma. The aim was not to decorate the simulation, but to reveal it.