zeno

Zeno is a node-based visual programming framework for building those simulations. Picture a Houdini-like node graph but open source, built for technical artists and simulation engineers.

MPL-2.0 license, C++ core. You connect nodes to build simulation pipelines: meshing, physics solvers, rendering, data processing. Supports OpenVDB, CUDA GPU acceleration, and real-time preview. The node system is extensible. Write custom C++ nodes for your specific simulation needs.

Zenus Technology offers commercial licensing and support, though exact pricing isn't publicly listed. The open source version under MPL-2.0 is free for use. You can modify it but must share changes to Zeno's own files. Solo VFX artists or researchers: the open source version gives you a capable simulation platform for $0. Small studios: free, add custom nodes for your pipeline. Larger studios: contact Zenus for enterprise support and potentially proprietary extensions.

The catch: and velocity means a small community. If you hit a bug or need help, you're largely on your own. The node-based paradigm has a learning curve, and documentation is limited compared to commercial tools like Houdini. For production VFX, Houdini is the industry standard. Zeno is the open source alternative for teams that can't or won't pay SideFX's licensing fees ($2K-4.5K/year).