Belgian Amiga Club - ADF Collection/BS1 part 23.zip/BS1 part 23/C-light d1.adf/Documentation.txt

Text File | 1988-10-15 | 22KB | 378 lines

                  Creating Animations with C-Light

                      0) Introduction
                      1) Design and Generation.
                      2) Creating an ANIM file.
                      3) Playback of animation.
                      4) An example.
                      5) A tutorial on using ED.

0) Introduction

     There are two disks included as part of C-Light.  The disk labeled
C-Light contains the scene editor, ray-tracer and View and Video tools.
The second disk, labeled Animate contains the animation creation tools
MakeAnim and PlayAnim as well as some demonstrations and examples.  Be
sure to create backup copies of the disks before proceeding.  It is
recommended that you read the C-Light manual before reading this document.
     To view the demonstration movies on the Animate disk, open the Movies
drawer and double click on the icon of the movie you wish to view.  The
screen will turn black while the movie is being loaded into memory, then
the first frame will appear.  To start the movie, click once with the left
mouse button.  To stop the movie, click again with the left mouse button.
     This document is an addendum to the C-Light manual, serving to explain
the use of the MakeAnim and PlayAnim tools for creating your own animated
movies.  (The terms movie and animation will be used interchangably in the
following text as will the terms picture and frame.)  Animations can be
created in any mode (low-res, non-interlaced, interlaced, overscanned.)
IFF pictures created with other programs can be included in an animation also.
Note that you can NOT mix modes within an animation.  If the first frame is
low-res and non-interlaced then the rest of the frames must be low-res and
interlaced.  Interlaced animations will have a tendency to be slower because
more of the screen has to be changed.  Also, having two floppy disk drives is
almost essential (although a RAM disk can probably be used in place of a
second floppy drive.)

1) Design and Generation

     The first step in creating an animation is to dream up some idea that
you would like to see animated.  This is probably the part of any task that
is the most fun.  Once you have the idea you then have to figure out how to
make it happen with the tools and resources you have available.
     Producing animations with C-Light involves breaking the motion in the
movie you are going to create into individual frames that are slightly
seperated in time; just like the frames of film in a reel of movie film.
Each frame is slightly different from the previous one so that when shown
rapidly in sequence, the eye is tricked into seeing smooth motion on the
screen.  Probably the best way to create this sequence of images with
C-Light is a technique known as key-framing.  Key-framing allows you to
control motion by picking out the most important moments (or key frames)
in the movie and using these to determine the locations of all the objects
for all the frames inbetween.  Thus, for example, to create a movie of a
sphere and cube melting together, you might pick a scene where the cube and
sphere are seperate as one key frame and one where they are melted together
as another key frame.  Then, since these two key frames tell you the starting
and ending locations for the cube and sphere, you can figure out (using some
simple math) where the cube and sphere are located for all the frames
inbetween the two key frames.  For example, if the sphere starts at
x = -100, y = 0, and z = 0 and stops at x = 0, y = 0, z = 0 and there
are 8 frames inbetween the key frames (for a total of ten frames in the
movie) then the positions for the sphere in each frame are:

     Frame       X Position  Y Position  Z position
       1            -100          0           0
       2             -89          0           0
       3             -78          0           0
       4             -67          0           0
       5             -56          0           0
       6             -45          0           0
       7             -34          0           0
       8             -23          0           0
       9             -12          0           0
      10               0          0           0

     In order to figure out how much the position changes for each frame,
just divide the total change in position between key frames by the total
number of frames minus one.  Thus the x position for the sphere is:

         Position change =  +100
         -----------------------   =  11 (its ok to round it off)
         10 frames total - 1 = 9

So starting at x = -100 the sphere moves 11 units to the right for each frame.
     The MakeAnim tool that will be used to combine the pictures into a
single movie will automatically make the movie looped.  This means that
when the movie reachs the last frame it will go back to the beginning and
start again.  Thus if you want to make a movie that repeats the same motion
over and over (like a spinning Enterprise) you have to make sure the last
frame and first frame flow together smoothly.  This just means that you have
to have the same amount of motion between the first and last frames as between
any of the inbetween frames.  (For example, in the Enterprise animation, the
ship rotates 1/16 turn each frame and when the movie reaches the last frame,
another 1/16 turn will make it the same as the first frame.  Thus when the
first frame is played again right after the last frame, the motion looks
smooth.)  If you run the movie play back tool PlayAnim from CLI you can
control precisely the number of times a movie will repeat before stopping
(from 1 to 999,999 times.)
     Now this may sound like a lot of work and it can be if your
picture is very complicated and there is a lot of motion in it.  However,
for most movies it will take only an hour or two to create the scene
description files for all the frames once you get the hang of it.
     There are some simple tricks you can use to speed things up too.
For example, to create the Enterprise animation (included on the Animate
disk in the Movies drawer) a detailed picture of the Enterprise was first
created.  Then, instead of figuring out a new position for each part of the
ship for each frame as the ship rotates, the VIEW function in C-LightII was
used to rotate the whole ship for each frame.  Thus, once the ship was
created, it only took a few minutes to create all the scene description files
for the animation (just change the VIEW rotation, save the picture, change
the rotation, save, change, save, etc.)
     Being organised also helps keep things simple when creating an
animation.  Make up a list showing the position for each object for each
frame and use it as a checklist when creating the scene description files
for all the frames with C-LightI.  Be sure to give each file a unique name
that will make it easy to figure out what order they go in later.
(Melt1, Melt2, Melt3...)
     Now, once the scene description files for all the frames have been
created each picture has to be calculated using C-LightII.  This is done in
exactly the same way as it would be for a single picture so refer to the
C-Light manual for instructions on calculating a picture.  It's ok
if the pictures fill up more than one disk as will be shown in the next
section.  You can see that if the scene is complicated (so that it takes a
long time to calculate a single frame) then it can take a LONG time to
calculate all the frames in a movie.  To give you an idea of how long, the
Enterprise animation took about one week to calculate, doing two pictures a
day.  You can speed things up by turning off shadows, using less lights and
using fewer objects.  The reason it is so slow is because of the
incredible number of calculations that must be done.  Each dot on the
screen (pixel) requires about 100 calculations (for say, a picture of
a room with one light and no shadows).  Thus for a non-interlaced,
non-overscanned (320 pixels by 200 pixels) movie with 16 frames this means:

       100 * 320 * 200 * 16 = 100,024,000 calculations!

Even an Amiga takes a little while to accomplish a task of this complexity!
Movies also take up a lot of disk and RAM space.  An Amiga with 512K of RAM
can playback a movie no larger than about 210K.  Larger movies can be played
if you have more than 512K RAM.  The largest movie that can be created by
MakeAnim without a hard disk drive is the size of one floppy disk (880K).
     For the advanced user, an example program called Spheres.c is
included to show how to create scene description files from a program.
In this way you can animate hundreds of objects without having to
shift them individually for each frame.  By studying this program you
can also learn the format of the scene description files written by 3)C-LightI
and read in by 3)C-LightII.  These files are standard ASCII text files and
can be read and modified using any text editor.

2) Creating an ANIM file

     Once you have created all the individual frames for a movie, they have
to be put together in the proper order and saved in a single file.  Also,
in order to fit as many as possible in the memory of your Amiga, the
pictures have to be compressed into a more compact format.  The ANIM
format was devised to give us a standard way to compress movies into
a common format.  It achieves the compression of a sequence of pictures
into a smaller space by storing only the differences between each frame
instead of the entire picture.  The MakeAnim utility has been included as
a part of C-Light to automatically compress a sequence of pictures and
create an ANIM file from them.
     To use MakeAnim there are two simple preparations you have to make.
First, you need a blank disk that has been given the name TMP.  (See
the "Introduction to Amiga" manual for instructions on formating a blank
disk and relabeling it or see the example in section 4.)  This disk will
be used as a temporary work space by MakeAnim.  [To use MakeAnim with a
hard disk drive, use the ASSIGN command to make your Amiga think that
the TMP: disk is a subdirectory of your hard disk.  For example:

             ASSIGN TMP: dh0:WorkArea/Movies

The ASSIGN command must be issued from a CLI window.  See section 5 below
for instructions on creating a CLI window.]
     Second, you need to create a list that tells MakeAnim where to find all
the pictures that make up your movie.  If you have a text editor you can use
it to create the list (make sure to save the file as text-only so that all
the text formating characters are not included.)  If you don't have a
favorite text editor you can use the simple one that came with your Amiga.
It is called ED and must be run from a CLI window.  If you are not familiar
with ED or running programs from the CLI, see section 5 below for an easy
step by step tutorial on using ED.
     This list, which tells MakeAnim where to find all the pictures in your
movie, is called a script file.  It has the following format:

DiskName:Movie_Name
Time  DiskName:Frame_1_Name
Time  DiskName:Frame_2_Name
Time  DiskName:Frame_3_Name
Time  DiskName:Frame_4_Name
Time  DiskName:Frame_5_Name
      etc...

The first line tells MakeAnim what the name of the final ANIM file will
be and where to put it.  The disk name can also include the names of
drawers (subdirectories) such as:

            Movies:Melt_Drawer/Melt1.ilbm

The next lines tell where the pictures are, what order they go in, and
how long each one should stay on the screen.  Again, the disk name can
include drawers.  The order of the pictures is the same as their order
in the script file (the first one will be shown first, the second one
second, etc.)  The time entry is a number that tells how long each
picture should stay on the screen.  This gives you complete control
over how fast things change in any part of your movie.  The time is
in multiples of one sixtyth of a second (1/60 second).  Thus an entry of
zero means to show the current frame as fast as possible, an entry of one
means wait 1/60 second before going to the next frame, an entry of 2 means
wait 2/60 second before going to the next frame, etc.  So if you want the
movie to run at about the same speed as a movie projector (24 frames/second)
try a time value of three.  The following is an example of a complete script
file:

Animate:Enterprise
0 WorkDisk_1:Enterprise/Enterprise1.ilbm
0 WorkDisk_1:Enterprise/Enterprise2.ilbm
0 WorkDisk_1:Enterprise/Enterprise3.ilbm
0 WorkDisk_1:Enterprise/Enterprise4.ilbm
0 WorkDisk_1:Enterprise/Enterprise5.ilbm
0  WorkDisk_1:Enterprise/Enterprise6.ilbm
0 WorkDisk_1:Enterprise/Enterprise7.ilbm
0 WorkDisk_1:Enterprise/Enterprise8.ilbm
0 WorkDisk_2:Enterprise9.ilbm
0 WorkDisk_2:Enterprise10.ilbm
0 WorkDisk_2:Enterprise11.ilbm
0 WorkDisk_2:Enterprise12.ilbm
0 WorkDisk_2:Enterprise13.ilbm
0 WorkDisk_2:Enterprise14.ilbm
0 WorkDisk_2:Enterprise15.ilbm
60 WorkDisk_2:Enterprise16.ilbm

Note that the pictures are located on two different disks in this
example (WorkDisk_1: amd WorkDisk_2:).  Also, on WorkDisk_1: the pictures
are in a subdirectory (drawer) while on WorkDisk_2: they are in the main
level directory.  It is a good idea to have the final ANIM file reside on
a different disk from those containing the pictures so that you don't run
out of space.  The time values are all set to zero so that the movie will
run as fast as possible except for the last one which is set to 60.  This
means that the movie will pause for one second on the last frame before
going back to the first frame.  (There can be as many spaces as you like
between time and picture name, but there must be at least one!)  All
these variations show the flexibility that is allowed in creating a script
file.
     Once you have created the script file, run MakeAnim.  If you run it
from Workbench it will ask you for the name of the script file (a disk name
and/or drawer name can be included too.)  [If you want to run from CLI, just
run MakeAnim and it will give you instructions.]  Once MakeAnim has the
script file name, the rest of the process is automatic.  A window will
open that will tell what is currently going on in the process of compressing
and storing the pictures.  At various points in the process you will be asked
to insert different disks so that MakeAnim can access them (first it will
look at all the pictures and write out some temporary files to the TMP disk,
then it will take one picture and all the TMP files and create the final ANIM
file on the output disk.)  This process really requires two disk drives.
It is possible to do it with only one, but you'll wear your arm out swapping
disks.  If you have a RAM expansion the RAM disk can be used as a second
drive.  Just copy all the pictures to the RAM disk and use RAM: for the
disk name in the script file.  Alternatively, you can use the ASSIGN
command to make your Amiga think the RAM disk is the TMP disk.  Just
issue the command:

                 ASSIGN TMP: RAM:

from a CLI window.  See section 5 below for instructions on opening a
CLI window.
     Even with two disk drives you should be intelligent about which drive
you put a disk into.  Try to place disks in a drive such that you never have
two disks being accessed from the same drive.  For example, MakeAnim first
asks for a picture disk, then asks for the TMP disk.  Don't put the TMP
disk in the same drive as the picture disk or you will have to constantly
swap them.  Instead, place it in the second drive and everything will
procede smoothly.  Similarly, don't put the TMP and the final output disk
in the same drive.  You can stop the process at any time by typing
Control-C (hold down the CTRL key and the C key at the same time.)
     The process is relatively quick; it usually takes only five to
twenty minutes to create the final ANIM file depending on the length
of the movie and the amount of motion that occurs within it.

3) Playback of Animation

     The PlayAnim tool is used to show your movie after the ANIM file has
been created. There are two different ways to play it back from Workbench.
[To playback from CLI, just run PlayAnim and it will give you instructions.]
In the first method you simply double click on the icon for the animation
you have created.  This requires that a copy of PlayAnim is in the main
window for the disk that contains the ANIM file (or you can change the
tool type for the movie to point to the disk that has PlayAnim on it.)
To use the second method, just double click on the PlayAnim icon.  A
requestor will ask you for the location/name of the ANIM file you wish
to view.
     Once the ANIM file has been read in by PlayAnim, the first frame of
the movie will appear.  To start it playing, just click in the screen once
with the left mouse button.  When you want the movie to stop, click again
with the left mouse button.  This method is designed to give you the most
precise control of start and stop times when patching together several
movies into a longer movie on your video tape recorder.
     More precise control of the number of times the movie repeats is
possible by running PlayAnim from CLI.  Also, you may notice that the
movie flickers a little when shown on your Amiga monitor.  This is because
interlace is automatically turned on by PlayAnim in order to get the best
quality when recording on a video tape recorder.  The interlace feature
can optionally be turned off when PlayAnim is run from CLI.  (Run
PlayAnim from CLI to get instructions on how to set these options.)

4) An Example

     This section describes how to create a movie using some example
pictures included on the Animate disk.  For demonstration purposes a
set of pictures, showing a ball spinning around a rotating cube, has
been included in the Pictures drawer on the Animate disk.  A script file
and the C-LightI scene description files have also been included in this
drawer.  Make sure your copy of the Animate disk is labeled Animate; use
the Rename item in the Workbench menu to rename it if it is not.
     First create a TMP disk by putting a blank disk in your Amiga, select
the disk icon that appears and then select Initialize from Workbench's Disk
menu.  Then select Rename from the Workbench menu and change the disk name
from blank to TMP.
     Now, to turn the pictures into an animated movie, double click on the
MakeAnim icon.  A requestor will appear asking for the name of the script
file.  Enter the name:

             Animate:Pictures/b.script

which gives the name and location of the script file.  You can use an
editor to look at this script file as a working example (see section 5
if you don't know how to use a text editor.)  The script file contains
the locations/names of all the pictures that will be used to make the
movie and tells MakeAnim to put the completed movie in the main window
(top level directory) of the Animate disk and to call it Ball&Cube.
     After you have typed in the name, hit return and a small text window
will appear.  This window will keep you informed on the progress of the
movie you are creating.  After reading in the names of the picture files,
MakeAnim will ask for the TMP disk to be inserted.  Because there is a lot
of blank screen in this movie and not much motion, both the pictures and
the final movie will fit on the Animate disk with room to spare.  First
the pictures will be read in one at a time and compressed and stored a
s DLTA files on the TMP disk.  Then the first picture and all the DLTA
files will be combined into an ANIM file and stored on the Animate disk.
     When the process is complete, close the window for the Animate disk
and then reopen it.  There should now be an icon there that looks like a
reel of movie film.  Double click on that icon to play back the movie you
just created.  (See section 3 above for complete instructions on play back
of movies.)  That's all there is to it!

5) A Tutorial on using ED

     ED is a simple text editor that is included on your Workbench disk.
It is only callable from a CLI window (Command Line Interface window.)
The following steps can be used to create or examine a script file using ED:

   1) To get a CLI window call up Preferences and select CLI ON (see the
"Introduction to Amiga" manual for information on using Preferences.)
Exit Preferences by selecting SAVE, then close the Workbench window and
reopen it.  Open the drawer labeled SYSTEM.  A new icon will appear there
from now on called CLI.  Open a CLI window by double clicking on this icon.

   2) Click once in the CLI window to activate it, then type:

                    CD disk:drawer

where "disk" is the name of the disk you want to put the script file on
and "drawer" is the name of the drawer you would like it to be in (leave
out the drawer name if you want the script file to be in the top level
directory of the disk.)  Now type:

                    ED filename

(where "filename" is the name of your script file) and then hit RETURN.

   3) You are now in the ED editor and can type in the disk names, drawer
names, picture names and times for the script file.  You can use the cursor
keys (with the arrows on them) to move around while typing and can use the
BACKSPACE and DEL keys to erase mistakes.  Holding down CTRL and B at the
same time will delete a whole line.  When you are done you can save your
work to disk by hitting the ESC key, then the X key, then RETURN.

   4) You are now back in the CLI window.  If you want to close the
CLI window, type ENDCLI.  If you run into trouble at any time and want
to get out of ED, just type ESC, then X, then RETURN.  See the "AmigaDOS
Users Manual" if you would like more information on using ED.