1. The Motion Dynamics of Snakes and Worms
Ryan Kern

2. Overview Gavin Miller – SIGGRAPH 1988 Mass-Spring system
Explicit Euler Integration

3. Mass-Spring system Series of connected cubes representing segments
Each cube is a lattice of springs
Mass at each corner
Spring along each edge and face-diagonal

4. Generating Motion Traveling sine wave Directional Friction
Varies the “natural” length of axial springs with time and position along body
Directional Friction
Prevents backwards movement

5. Motion Types Rectilinear Progression Horizontal Undulatory Progression
“inchworm” motion
Horizontal Undulatory Progression
More familiar snake-like motion
Also “sidewinding” and caterpillar motion

6. Maya Integration MEL script Skeletal / joint-chain data
Few nodes (n+1)

7. Problems Unknown constants!
Mass
Segment length
Amplitude
Period/frequency
Only interested in lateral movement, so the y-coord is fixed

8. Potential changes Write a plugin More motions
Parameter changes require simulation restart
NURBS surface generation using lattice as control points (allows for volume-preservation)
More motions
With missing data, non-level surfaces are possible (sometimes easy)

9. Demo
I apologize for the head