Stable Inverse Dynamic Curves
ACM Transactions on Graphics, December 2010 (Proceedings of the ACM SIGGRAPH Asia 2010 Conference)
Abstract
2d animation is a traditional but fascinating domain that has recently regained popularity both
in animated movies and video games. This paper introduces a method for automatically converting
a smooth sketched curve into a 2d dynamic curve at stable equilibrium under gravity. The curve
can then be physically animated to produce secondary motions in 2d animations or simple video
games. Our approach proceeds in two steps. We first present a new technique to fit a smooth
piecewise circular arcs curve to a sketched curve. Then we show how to compute the physical
parameters of a dynamic rod model (super-circle) so that its stable rest shape under gravity
exactly matches the fitted circular arcs curve. We demonstrate the interactivity and
controllability of our approach on various examples where a user can intuitively setup
efficient and precise 2d animations by specifying the input geometry.
Download
- Paper: [PDF]
- Accompanying video (core of the method): [MPEG4]
- Supplemental video (applications): [MPEG4]
- Supplemental material I (technical details): [PDF]
- Supplemental material II (evaluation of our geometric fitting method): [PDF]
- Executable code: [Linux 32 bits] [Linux 64 bits] [Mac OSX] [Windows]
Artistic contribution:
Gibule's character was created by Laurence Boissieux (INRIA).