Intersection of two cylinders. The radii remain constant during
the animation, distance and angle between their axes change.
When the cylinders touch each other, a double point of the
intersection appears.
The intersection of two cylinders gives a nice collection
of space curves. If the two cylinders touch each other in
one point, then the intersection curve has a double point
at that point (making a figure 8 like curve, in the middle
of the animation).
In this special case the cylinders have the same radius and
their axes meet. Therefore we have two symmetry planes which
interchange the two cylinders. This implies that the intersection
of the two cylinders must lie in these two planes - we get two
ellipses as intersection curves.
In architecture this has been used in the ceilings of roman
cathedrals.
These anaglyph imagee show two touching cylinders; one rotates
about the common normal. Their intersection curves are
therefore figure-8-like in the whole animation.
