  Secondary animation effects are essential for liveliness. We propose a
simple, real-time solution for adding them on top of standard skinning,
enabling artist-driven stylization of skeletal motion. Our method takes a
standard skeleton animation as input, along with a skin mesh and rig weights.
It then derives per-vertex deformations from the different linear and angular
velocities along the skeletal hierarchy. We highlight two specific applications
of this general framework, namely the cartoonlike "squashy" and "floppy"
effects, achieved from specific combinations of velocity terms. As our results
show, combining these effects enables to mimic, enhance and stylize
physical-looking behaviours within a standard animation pipeline, for arbitrary
skinned characters. Interactive on CPU, our method allows for GPU
implementation, yielding real-time performances even on large meshes. Animator
control is supported through a simple interface toolkit, enabling to refine the
desired type and magnitude of deformation at relevant vertices by simply
painting weights. The resulting rigged character automatically responds to new
skeletal animation, without further input.
