Graphics Reference
In-Depth Information
The Passing Position
The passing position describes the moment in the walk cycle when the
body is supported by only one of the legs, which is held in a vertical position
with little or no bend at the knee. At this point the leg is positioned directly
below and in line with the torso. The other, nonsupporting leg is positioned
alongside the weight-bearing leg and swings forward past the supporting
leg—hence the term
passing position
. The knee of this leg is bent at this
stage to allow the foot to be raised to clear the ground. During the passing
position the kinetic energy of the figure's forward movement is converted into
gravitational potential energy as the figure rises slightly. This energy is then
released as the leg swings forward and the body drops and completes the
stride.
If we now take a look at the two passing positions and both the strides as
a sequence of keyframes, we can see how the entire cycle works and can
analyze it in its simplest form.
FIG 5.30
The walk cycle keys. From
left to right: stride, passing position,
stride, passing position.
The leg movement is clearly the primary action of a walk cycle, but the walk
action is not limited to the movement of the legs alone. In the following
phases of the walk, we can see how all parts of the body work together to
produce a complete sequence. The phase order in this instance is an artificial
one and quite arbitrary, since there is no distinct beginning or end to this
cyclical movement. However, the sequence holds as a general guide, though
variations will occur in different walks.
