The following post is an animator program for the HP48SX or GX, along
with six "movies."  

The animator accepts n GROBs on levels 2 through n+1, with n on level 1.
(Just like ANIMATE on the G/GX.)  It is only 343.5 bytes big, entirely in
User RPL, and is controlled using these keys:
[Cursor-UP]: Single step forward one GROB
[Cursor-DOWN]: Single step backward one GROB
[ENTER]:Animate continuously in the current direction (forward or backward)
Any other key except [ON]: exit

I wrote this animator program as an attempt to combine the continuous and
single-step (stop-frame) animators in C. Patton's Suite3D.  If someone can
make it smaller than 343.5 bytes but retain it's features, I'd like to know
how.  The ability to animate a GROB sequence, in either direction, stop-frame
or continuously, at will, has been very helpful to me when giving presentations
to students on the HP48 Overhead Classroom Display.

The movies are:
A derivative movie (secant lines approaching a tangent)
and integral movie (Riemann sums approaching an an integral)
eccentricity (a conic section animation)
taylor series (from the manual, but improved)
dragon (watch a line fold itself into the space-filling curve)
cube3d (stereoscopic rotating 3-d cube, very impressive.)

credit where credit is due:  Lynn Garner, Wayne Rust, J.A. Eidswick,
Charlie Patton, Donald R. Snow.

I sent these to Mr. Horn a while ago, but I don't know if he judged them to
be of "goodies" quality or not.


ANIM: Animation utility by Carl Robert Gibbons

I couldn't think of a way to make this animator do what it
does and run faster or use less memory.  User RPL & ONLY 343.5 bytes!

ANIM just requires n graphics objects on levels 2 through n+1
and the number n on level 1.  The graphics objects can be of
any size.  They are simply placed in the graphics screen,
one after another, to provide the illusion of motion.

To control the animation:
* Press [Cursor-Up] to single-step (stop-frame) through the
  grobs one at a time.  Press [Cursor-Down] to single-step
  through the grobs one at a time and in reverse order.
* Press [ENTER] to resume continuous animation (Either
  forward or backward, depending on which [Cursor-key] was
  last pressed).
* Press any other key (except [ATTN]) to stop.  The n grobs
  and the number n remain on the stack.

I haven't seen the forward/backward with step animation feature
in any other animator program, including the ANIMATE command
built into the HP48G/GX.

This program began as an attempt to combine the continuous
movie program and the single-step movie program found in
Charles Patton's Suite3D package.

Here are some sample movies with which to try the ANIM animator:
They are stored with the .MOV extension as lists of graphics
objects;  all you have to do is execute OBJ\-> and they are
ready to be animated.

CALCMDER.MOV -- Graphical animation of the derivative (a secant
                line approaching a tangent line)
CALCMINT.MOV -- Graphical animation of a Riemann Sum (rectangles)
                approaching an integral
CUBE3DM.MOV  -- Two 3-d rotating cubes, which are situated so
                that by relaxing your eyes and letting the two cubes
                merge into one, you obtain a true 3-d optical
                illusion of a rotating cube.  (Stereoscopic 3D!)
DRAGONM.MOV  -- Watch the space-filling fractal "dragon" curve
                take shape.  (The dragon was drawn using some
                turtle-graphics routines.)
ECCM.MOV     -- Conic sections of various eccentricities, animated
                from eccentricity 0 through infinite (ì) eccentricity
TAYM.MOV     -- Animation of Taylor's polynomials (like the one in
                the Owner's manual, except a lot cleaner and using
                a lot less memory)

(from BYU HP Calculator Club notes #8)