The BioDigital Human Particle System

Tarek Sherif

Lead Graphics Engineer, BioDigital

Background

• We frequently want to visualize
  • Fluid motion
  • Molecular interactions
  • Drug effects

Before the Particle System

• Particles would be rendered as low-res spheres
• Each particle would be manually animated by an artist

Particle System

• These effects can be efficiently rendered with a particle simulation
  • Draw points
  • Fine-grained simulation components to apply forces/constraints

Architecture

• Particles are separate arrays of properties
• Position
• Velocity
• Color
• Age

Architecture

• Particles updated each frame by components
• Creators: Initialize a property
• Updater: Update a property each frame
• Constraint: Ensure a property remains within bounds

Current Component List

• Creators
  • cube-position, directional-velocity, point-position, sphere-position, cylinder-position, lifetime, random-velocity
• Updaters
  • age-color-blend, brownian-motion, cylindrical-force, friction, gravity, path, radial-force, sprite-animation, uniform-force
• Constraints
  • lifetime-kill, lifetime-stop, path-kill, path-radius, path-stop, shape-bounce, shape-kill, shape-stop
• Shapes
  • cube, cylinder, plane, sphere

Architecture

• Each component has a minimal function in the sim
• Allows artists to combine them in expressive ways

Applications

• Initially limited to basic processes and ambient effects

Applications

• Additional features rolled out over time
  • Textures
  • Component parameter animations

Thanks!