Work

Projects ordered by recency.

GeometryDB and Proximity Deformer

Meta | Software Engineer, Digital Humans | 2024–2026

A graph-based C++ procedural execution framework for real-time deformation and simulation workflows, and a real-time proximity deformer built on top of it.

  • Designed and implemented GeometryDB: a parallel, attribute-level DAG framework in C++ with Python bindings.
  • Built a real-time proximity deformer on top of GeometryDB with automatic bindings generation.
  • Built a Rerun-based visualization suite as first-class graph nodes.

C++ · Python · Deformers · Cloth Sim · Real-Time · Node Graph

Jiggle Spring Deformer (and Wiggly Splines)

Epic Games | Physics Software Engineer | 2022

Real-time zero-restlength spring deformer for Unreal Engine, built to restore ballistic secondary motion to ML Deformer output. Per-vertex stiffness and damping estimated from offline flesh sim data; forward-looking tracking dependency removed for real-time use. Picks up a thread from wiggly splines work on WALL·E.

  • Zero-restlength springs connect a dynamic mesh to an animated target; per-vertex stiffness and damping estimated from offline flesh sim to approximate full simulation ballistics
  • Linearized backward-differencing tracking: removes the forward time dependency from Jin et al. for real-time use with one-frame lag
  • Implemented as an HLSL vertex shader in Unreal Engine's Optimus deformer framework

Unreal Engine · Deformers · FEM · Flesh Sim · Real-Time · SIGGRAPH

Skin and Muscles on 'Incredibles 2'

Pixar | Senior Software Engineer | 2016–2018

Led skin and muscle simulation developments on Incredibles 2.

  • New robust skin tracking algorithm using 2D ray-tracing over mesh surfaces
  • Non-uniform projection spring constraints for art-directed skin behavior
  • FEM muscle development

PAL · PhysBAM · FEM · Skin Sim · Flesh Sim · Muscle Sim · SIGGRAPH

Fluid Simulation on 'Brave'

Pixar | Senior Software Engineer | 2010–2012

Large-scale distributed multiphase fluid simulation for the river and cauldron sequences.

  • Distributed PLS fluid simulator
  • Deformable level set collision objects
  • Windowed source
  • Divergence field

PAL · PhysBAM · Fluid Sim · Houdini · SIGGRAPH

Armature Rigging & Rigid Fracture on 'Brave'

Pixar | Senior Software Engineer | 2009

Simulation-driven armature rigging workflow and virtual-node rigid fracture in Houdini.

  • Soft body simulation for rigging
  • Highly detailed rigid fracture for effects

PAL · PhysBAM · Rigging · Houdini

Flesh & Skin Simulation on 'Brave'

Pixar | Senior Software Engineer | 2009–2012

Layered FEM flesh and skin simulation on the bears and horses of Brave. Independent volumetric flesh and sliding triangular skin simulations, both biphasic, with constitutive models that adapt stiffness to hold across slow secondary motion and fast ballistic action.

  • Layered simulation: volumetric FEM flesh allowed to break silhouette, topped by an independent triangular skin sim that slides over the flesh without breaking profile
  • Biphasic constitutive model: stiffness increases beyond a deformation threshold, so a single parameter set holds across slow secondary motion and fast ballistic action
  • Skin constraint forces split into normal (shape preservation) and tangential (sliding), applied sequentially without a coupled solve
  • Rest state retargeting on both flesh and skin: rest states update each timestep to match the animated target, so simulation cooperates with animation rather than fighting it

PAL · PhysBAM · FEM · Skin Sim · Flesh Sim · SIGGRAPH · Patent

Physics Abstraction Layer (PAL)

Pixar | Senior Software Engineer | 2008-2018

Architected and led PAL, a C++/Python simulation scene graph used across most Pixar films from Toy Story 3 through Incredibles 2.

  • Technical lead and architect for PAL core systems.
  • Supported production use from Toy Story 3 through Incredibles 2.
  • Bridged research code to production reliability.

C++ · Python · FEM · Cloth Sim · Flesh Sim · Hair Sim · Fluid Sim · Node Graph

Fluid Simulation on 'WALL-E'

Pixar | Software Engineer | 2007

PLS fluid simulator for Mow's backpack.

  • Particle Level Set fluid simulation for Mow's backpack
  • Distributed simulation across multiple machines via MPI
  • Level set merging and marching cubes surface reconstruction

PhysBAM · Fluid Sim

Character Driving System on 'WALL-E'

Pixar | Software Engineer | 2006

Custom widgets for path-following character driving system.

  • Spline path with ground map sampling
  • Timing knot widgets for animator control
  • Ground-locked and flying widget modes

Rigging · Animation · UI Design

Simulating the Devolved: Finite Elements on WALL·E

Pixar | Senior Software Engineer | 2005–2008

Tetrahedral FEM flesh simulation for WALL·E's devolved humans, from jelly-blob concept through final production. Ran on every shot with a human character, operated by animators. Co-authored the SIGGRAPH 2008 sketch.

  • Invertible tetrahedral FEM with co-rotated linear elasticity: stable through the extreme nonphysical poses Pixar animation demands
  • Rest state retargeting (US8290757B2): each element's rest state updates each timestep to match the animated pose, so the sim adds ballistic motion rather than fighting the rig
  • Laplace-based surface-to-volume transfer for both weight maps and animation targets; no interior rigging required
  • Two-way rigid body coupling and MPI parallelism: scales to crowd sequences with hundreds of simulated characters

PhysBAM · FEM · Crowd Sim · MPI · Rest State Retargeting · SIGGRAPH · Patent

Creature Dynamics at ILM

ILM | R&D Simulation Engineer | 2002–2005

Rebuilt ILM's flesh and cloth simulation pipeline, then advanced it production by production — culminating in Davy Jones, widely considered one of the greatest CG creatures ever put on screen.

  • Replaced ILM's flesh simulator with PhysBAM for Van Helsing's Hyde — first CG creature to hold up at full screen with nowhere to hide.
  • Deforming level set colliders and level set time interpolation for T3's leather-clad TX, keeping clothes on at high speed.
  • Adaptive subdivision collision detection for cloth on thin geometry — deployed on Harry Potter 3 and Pirates of the Caribbean.
  • Pseudo-muscle activation on EP3's Varactyl using holistic tetrahedral meshes with spatially varying material parameters.
  • Introduced embedded tetrahedral meshes on Davy Jones's tentacles, cutting simulation from hours to under a minute per frame.
  • Drove adoption of PhysBAM as ILM's deformable body simulation standard, which was a disruptive change that remains in use at the studio decades later.

C++ · PhysBAM · FEM · Flesh Sim · Cloth Sim · SIGGRAPH