Soap, Bubbles & Surface Tension
Bubbles seem to be one of the constantly recurring themes in CGI. After researching how soap films and soap bubbles work in real life it became apparent, that when bubbles stick together they do a bit more than just somehow intersect each other.
Modeling / Geometry
Thankfully there are some notes by Andrew Glassner on the topic. Turns out that bubbles always try to minimize their surface area and thus their geometry is only dependent on their radii.
To generate this geometry I've implemented Glassner's exmaple code in Xpresso and Python in Cinema4D. And with a little help from some dirty boolean objects I've generated the bubble's geometry.
Bubble Geometry generated by Xpresso and Python in C4D.
Shading
Turns out a soap film shader is a tad more than just a refractive material. In fact the appearance of soap bubbles is defined mostly by the colorful interference patterns that form due to the very small thickness of the soap & water layer that forms the bubbles.
To recreate these intricate patterns I've dug deep into Octane's mix material to combine multiple procedural shaders (mostly noise and gradients) with a pre-rendered texture out of After Effects.
Shader Details
This is the bubble shader's node graph - if you're into that kind of stuff. Looks more complicated than it actually is. In parts due to the fact that I didn't want to use Cloth NURBS to give the bubble a thin appearance and instead relied on the shader to do so.
Animation
When it comes to animation I'm ususally quite lazy. This one was animated using no keyframes, instead relying on C4D's vibrate tag, animated noise, diplacer and jiggle deformer.
