See section 12.14.8 for projections in space.
The projection command takes one or two arguments.
If projection has one argument, it is a geometric object.
projection returns a new command which projects points onto
the object.
Input:
then:
Output:
Input:
then:
Output:
If projection has two arguments, the first arguments is a
geometric object as above, and the second argument is a point.
projection returns and draws the projection of the point onto
the object.
Input:
Output:
Input:
Output: