Intersection Of Two Cylinders
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.