The first animations truncate a regular polyhedron to the mid-points
of its edges, then switch to the dual model and truncate back
from the mid-points of its edges.
The second animations show the full range of an idealised truncation.
The edges are treated as lines rather than line segments. The edges
are cut in a ratio that ranges from -infinity to +infinity.
extremes of the range the circumsphere of the model grows to become
infinitely large. In order to view the transformation the truncated model
is scaled to maintain the circumsphere at a constant size. The effect on
the base polyhedron is to shrink it into the centre at the
The animations were made with the following scripts
An idealised truncation of a
from -infinty to +infinity.
The model is scaled to have a circumsphere of constant size.
The tetrahedron does not have central symmetry, and hence the limit of
truncation at the two extreme ratios produces different models. This
is seen as a break in the animation cycle at the switch from +infinity
view animation (1.4Mb)