In this paper, we propose an efficient technique for
the animation of flexible thin objects.
Mass-spring model was employed to represent the flexible
Many techniques have used the mass-spring model to
generate plausible animation of soft objects.
The easiest approach to animation with
mass-spring model is explicit Euler method, but
the explicit Euler method has serious disadvantage that
it suffers from `instability problem'.
The implicit integration method is a possible
solution to overcome the instability problem.
However, the most critical flaw of the implicit method is that
it involves a large linear system.
This paper presents a fast animation technique for mass-spring model
with approximated implicit method.
The proposed technique stably updates the state of n mass-points in O(n)
time when the number of total springs are O(n).
We also consider the interaction of the flexible object and air in order to
generate plausible results.