Exhibit quadrilateral mesh plots in 3 movies of a drumhead.
The drumhead is initially stationary, but has a bump near one
edge. Yorick is solving a 2D wave equation to compute the
evolution of this bump.
The first movie is a filled mesh plot with color "proportional"
to the height of the surface of the drum. A few well chosen
contour levels (here 3) add a lot to a filled mesh plot.
The second movie is a "3D" perspective plot of the height of the
drumhead. In this movie, the mesh lines are drawn, which is
slightly confusing since the cells are not all the same shape.
The second movie is a "3D" shaded plot of the height of the
drumhead. Yorick computes surface shading based on the angle
of each cell from a light source.
As you watch this, you might reflect on the two dimensionality
of your retina. What Yorick lacks by way of 3D graphics is
really just fancy hidden surface algorithms; the simple
painter's algorithm used here and in plwf.i is easy to
There are two optional arguments to demo2: the first is the
number fo the movie (1, 2, or 3) you want to watch; the second
is a time limit on the duration of each movie in seconds (default
is 60 seconds each).
interpreted function, defined at i/demo2.i line 10