Former Pixar FX Artist Shares Multi-Layered RBD Workflow for Efficient Destruction Refinement

Destruction simulations present a persistent production challenge: once a director approves the overall motion and composition, adding fracture detail or making specific refinements can force a complete recalculation. Even minor changes to fracture patterns or piece behavior alter indexing, constraints, and collisions, affecting surrounding geometry and undoing work already locked in.

Jae Jun Yi, who spent 12 years as an FX Technical Director at Pixar Animation Studios, The Mill, and Blur Studio, developed a solution called Multi-Layered RBD Simulation. Presented as a poster at SIGGRAPH 2026, the workflow allows Houdini artists to build destruction in progressive stages, starting with a simple base simulation focused on composition and large-scale motion.

The process begins with a standard RBD simulation that establishes overall destruction direction and framing. Once approved, artists select specific pieces for additional detail either manually or through procedural conditions such as size, velocity, impact strength, or collision events. Those selected pieces are fractured again into smaller geometry.

The critical step is preserving motion continuity. Yi stores piece identifiers from the previous simulation as separate attributes before creating new fractures, maintaining a link between original and newly fractured pieces. Transform and motion attributes are transferred to the new pieces, which initially follow the inherited movement rather than immediately triggering a new simulation.

Each new piece transitions into active RBD simulation only when an artist-defined trigger is reached. Triggers can be set manually or generated from conditions like impact or velocity. This staged activation maintains physical continuity while allowing directors to request increasingly specific changes without cascading recalculations.

Yi emphasizes that the workflow extends Houdini's existing RBD toolset rather than introducing a specialized system unfamiliar to other artists. He acknowledges limitations for highly interconnected destruction or scenarios where pieces continuously interact, but the approach directly addresses the production bottleneck where art direction becomes progressively more detailed as projects develop.

Since leaving Pixar in 2025, Yi has worked as an independent filmmaker exploring AI in animation production. He released an AI-assisted animated short film titled Masha in 2026, which screened in the AI Frontier section of the Bucheon International Fantastic Film Festival.