Amiga Format 20/af020.adf/Script4D/readme.doc

Text File | 1980-02-23 | 26KB | 1,017 lines

********************************************************
DOCUMENTATION FOR AMIGA SCRIPT4D version 1.00   Jan 1991



Version 1.00 of the SCRIPT4D executable program is in the Public
Domain.  It may be freely copied and distributed provided that it
is always accompanied by this document in it's original form and by
the supplied example files.


Bug reports, comments, suggested enhancements and constructive critisism
of SCRIPT4D are most welcome - BY MAIL - to:

        Richard Swingwood
        181 Bergholt Road
        Colchester
        Essex  CO4 5AH
        England


SCRIPT4D was developed using Lattice C V5.05.

If I've used any trademarks in this document then I acknowledge that
they belong to someone.



===================================================================
INTRODUCTION
===================================================================

SCRIPT4D was created to ease the pain of creating animated sequences
using the SCULPT 3D/4D range of software.

I don't wish to imply that those packages are, in themselves, the
cause of any grief.  Personally, I find them a pleasure to use when
creating objects and scenes; the problem, for me, comes when doing
key-frame animations of any complexity.  It's a chore I can do
without.

What I envisaged was a method of taking my ideas about HOW & WHEN
objects in a particular scene should move and have them converted
into a SCULPT script file that would do the hard work for me.

Assuming my ideas could be expressed in some sort of consise language
then, if I made a pigs ear of the animation, rather than have to wade
through umpteen key-frame scenes recalculating object positions and
making changes I could simply change my definition of the motions -
the AMIGA could then do the hard work!

I haven't forgotten about the global animation facility in SCULPT,
which can also take a lot of the hassle out of animation; I just
find it unusable for complex motions that are not repetitive.

As it happens, SCRIPT4D could well be put to other uses because it is
not tied to SCULPT command syntax or file formats.

So here's SCRIPT4D.  It's by no means perfect or complete - I
need your feedback!



==================================================================
CONCEPTS
==================================================================

SCRIPT4D takes a 'scripting program' (program from now on) as input
an produces a file of SCUPLT script commands (script from now on) as
output.  The script is then used to drive SCULPT and produce the
animation.

It is executed from the CLI with a command of the form:

    SCRIPT4D   <progname   >scriptname

eg.

    SCRIPT4D   <Eye.prog   >Eye.script


A program has a basic layout of:

    FRAMES n

    ...declarations...

    ...procedures...

    ...controllers...

    END


The 'FRAMES n' specifies the number of frames in the animation.

Declarations are used to define arrays of values and 'smooth motion'
information.

Procedures generally contain, amongst other things, SCULPT script
commands that will be ouptut to the script.  Individual procedures
can be either active or suspended.

Controllers specify program actions to take place at specified
frames in the sequence.  Controllers are usually used to activate
procedures at the required frames.


Program execution occurs as follows:

    1)  An internal current-frame counter is set to 1

    2)  Any and all controllers that refer to the current
        frame are executed.

    3)  All active procedures are executed in the order
        they appear in the program.

    4)  The frame counter is incremented and, if it does not
        exceed the declared number of frames, execution
        continues at 2) above.


A skeleton program would be..

    FRAMES 50

    TO blink        /* procedure */
        ...commands...
    END

    TO nod            /* procedure */
        ...commands...
    END

    AT 1            /* controller */
        START nod
    END

    AT 5 25            /* controller */
        START blink
    END

    END


Thus the procedure 'nod' would be activated just before frame 1 and 'blink'
would be activated just before frames 5 and 25.
Each time they would remain active until explicitly suspended, either
by itself, by another procedure or by a controller.

Let's take a more detailed look at a procedure.  As we'll see later
this one will be used to make a modelled eye blink.  The commands
used will be more fully described in the COMMANDS section.

    TO blink
        SETUP
            blinkstep = 2            /* cos step 1 is 0 deg. */
            closingtime = 0
        END
        EXECUTE
                  /* select next angle for smooth motion */
        SMOOTH blinker blinkstep blinkangle
        'DESELECT ALL'
            'SELECT NAMED "Eye+Lid" '    /* script commands to.. */
            'WINDOW EAST'            /* rotate the eyelid... */
            'ROTATE CLOCKWISE %d '  (i) blinkangle
            IF blinkstep = 7        /* handle eye-closed time */
                FREEZE closingtime
            ENDIF
            blinkstep += 1
            IF blinkstep > 12
                SUSPEND blink 32000        /* ie. until reSTARTed */
            ENDIF
        END
    END


A procedure consists of two command blocks, SETUP & EXECUTE.
Commands in the SETUP block are executed at the time the procedure is
STARTed.  Those in the EXECUTE block execute for each frame that the
procedure is active.

In our example the SETUP block is simply initializing two variables:
'blinkstep' is used to keep track of how far through the 'blink' we
are,  'closingtime' will be used to keep the eye closed for a
variable amount of time (zero extra frames by default.)

Once 'blink' is active, the commands in the EXECUTE block are executed
for each subsequent frame.  The SMOOTH command will calculate a
suitable angle through which the eyelid should be rotated at the
current step in the blink.  The necessary SCULPT script commands are
then output.  Once the eye is closed, at step 7, it is 'frozen' in
that state for a variable number of frames, otherwise the step number
is incremented.  If the blink has completed then the procedure
SUSPENDs itself.

Note that SCRIPT4D still relies on you to specify the appropriate
SCULPT script commands, but it then gives you flexible & programmable
control over the content & occurrence of those commands in the output
script.



==================================================================
EXAMPLE PROGRAM
==================================================================

For the purposes of this description, I'll assume we want to animate
a blinking eye that floats up & down.  This in itself isn't complex
enough to warrant using SCRIPT4D but it provides a method of
demonstrating how SCRIPT4D can be used.

The approach we'll take is thus:

    a)  The animation will be 50 frames

    b)  A Take, named EYE has been created, all relevant
        options selected and details filled in.

    c)  A global SCENE containing OBSERVER, TARGET & LAMP(S)
        has been defined for the Take.

    d)  An scene, called EYEEYE, has been created and stored to
        disk.  The scene contains a single object.

        This object is named as follows:

                  ...Lid
                 |
           Eye...|
                 |
                 |...Ball
             |
             |
             |...Socket

        The centre of the eye sits at (0,0,0) and it is looking
        south.  The eyelid covers the top of the eyeball, tilted
        back about 45 degrees.  The socket is simply a cube in
        which the eye sits.

    e)  A scene will be created for every frame of the animation
        by loading in the 'base' Eyeeye object and then modifying
        it as required for that frame.


All the relevant files should accompany this program.  I suggest you
have a quick peek at EYEEYE.SCENE so you can see what's what!

Every frame of the Take will be a key-frame.  With the computer doing
the work there's no reason why not!  In any case, with complex
animations this usually needs to be the case.

The program, listed below can be found in the file 'Eye.prog'.
Use this to generate the script file with the command:

        SCRIPT4D  <Eye.prog  >Eye.script

Path names, both in the above command & in the supplied 'Take'
may need modifying depending on your system configuration.

There is a certain amount of 'housekeeping' required in the program,
resulting in something that appears too complicated for what we're
trying to achieve.  However, such housekeeping can be defined once in
a 'template' program and subsequently reused (with minor changes.)

Note that within the program comments are delimited by '/*' &  '*/'.


    FRAMES  50

        /* define a 7-step smooth motion for 0 thru 90 degrees */
    SMOOTHER blinking 0 90 7
        /* relative up/down motion in 10 steps */
    SMOOTHER floating -400 400 10

    TO init
        EXECUTE
        'LOAD TAKE "EYE" '
        SUSPEND init 32000    /* init suspended for 32000 frames! */
        END
    END

    TO getscene            /* gets base scene for each frame */
        EXECUTE
            'TAKE CURRENT FRAME %d' (i) frame
            'ERASE ALL'
            '(0,0,0)'
            'LOAD SCENE "Eyeeye.scene"'
        END
    END

    TO blink            /* how to make the eye blink */
        SETUP
        blinkstep = 2        /* 2 'cos 1st angle would be 0 */
        closingtime = 0
        END
        EXECUTE
                    /* select next angle for smooth motion */
        blinkangle @= blinking blinkstep   /* alternative to SMOOTH */
            'DESELECT ALL'        /* output script commands to.. */
            'SELECT NAMED "Eye+Lid"'    /* ..rotate eyelid */
            'WINDOW EAST'
            'ROTATE CLOCKWISE %d' (i) blinkangle
            IF blinkstep = 7    /* handle eye-closed time */
                FREEZE closingtime
            ENDIF
            blinkstep += 1        /* ready for next frame */
            IF blinkstep > 12
                SUSPEND blink
            ENDIF
        END
    END

    TO float            /* floating up & down */
        SETUP  floatstep = 1  END
        EXECUTE
            floatlevel @= floating floatstep
            'SELECT ALL'
            'GRABBER ON'
            '[0,0,%d]' (i) floatlevel
            'GRABBER OFF'
            floatstep += 1
            IF floatstep > 10
                floatstep = 1
            ENDIF
        END
    END

    TO savescene            /* saves scene & makes key frame */
        EXECUTE
            'TAKE KEY YES'
        'TAKE SAVE KEY FRAME SCENE'
        END
    END

    TO render            /* final script command */
        EXECUTE
        'TAKE PREVIEW'        /* OR  'TAKE RENDER ALL'  */
        END
    END


    AT 1                /* before anything else.. */
        START init            /* start once-off init */
        START getscene        /* start scene load.. */
        START savescene        /* ..and save procedures */
        START float            /* floating all the time */
    END

    AT 50                /* when all scenes generated.. */
        START render
    END

    AT 5                /* what to do at frame 5 */
        START blink            /* set it rolling */
    END

    AT 25                /* what to do at frame 18 */
        START blink            /* longer blink this time.. */
        closingtime = 7        /* ..by overriding default */
    END


    END    /* of program */


The 'housekeeping' is done by the init, getscene, savescene &
render procedures.

The output from this program (Eye.script) can be input to SCULPT
via the 'LOAD SCRIPT' menu option.


I feel it's worth reiterating on the idea of having one, or indeed
a set of, base objects that are modified from scratch for each key-
frame scene.

Imagine that our Eye was installed in a Head and that we wanted the
animation to show a blinking eye, wobbling in a nodding Head.
By having a base object of Head, pointing along one of the SCULPT
axes, containing Eye, also pointing along an axis, we have created
a known starting position of the object(s) for each key-frame scene.

If motions are performed from the bottom of the hierarchy upwards (ie.
Eyelid/Ball, Eye and finally Head) then there is no conflict between
them.

Imagine twisting the Head to one side and then trying to blink the
Eyelid (uummm.. rotate Eyelid about which axis...?).

Such a situation could arise if we base key-frame scene N on key-
frame scene N-1.

Using SCRIPT4D we can code each motion in a separate procedure and
then order the procedures within the program to match the hierarchy
of the objects.  The 'nodding, wobbling, blinking eye' would require
a program structure of the form:

    FRAMES n

    TO blink
        ...
    END

    TO wobble
        ...
    END

    TO nod
        ...
    END

    etc...

Different procedures could, of course, refer to the same part of an
object.  For example, you could have one procedure that blinked the
eyelid and another that made it flutter!  Either could then be
activated as & when required.

This approach is by no means definitive.  After you have studied
the avalable commands you may well decided on a better method.
Again, tell me your ideas!

When it comes to archiving your creations all you need to copy is
the SCRIPT4D program, the TAKE and the Global & base SCENE.  There's
no need to keep a copy of all the key-frame scenes because, if they're
needed again, they can be recreated automatically.  The saving in disk
space can be huge!


==================================================================
COMMANDS  &  program structure
==================================================================

The program file is free-form except that all 'tokens' must be
separated by white-space.  Case is not significant except within
string variables.

SCRIPT4D is fairly strict when it comes to syntax checking but there
are bound to be a few howlers, so take care -  this is version 1 after
all!

A variable, smoother & table can NOT have the same name.  However
a procedure can have the same name as any of these without causing
any conflct.




Literals                              Literals

    Three types of literal are recognised by SCRIPT4D:
    integers, floating-point & string (enclosed in double
    quotes.)  For example:

        1234
        55.7
        ":SCULPT/SCENES/"


Variables                             Variables

    Most SCRIPT4D commands use named variables to supply or
    store values.  Variable names are recognised by context
    when the program is translated.  Names must begin with
    an alphabetic character and can be up to 20 characters in
    length.

    A variable can hold any of the three literal types and is
    not restricted to any one type during program execution.

    There are two pre-defined variables:

        frame        holds the current frame number.
                This should be considered 'read-only'.

        nextframe    can be assigned the number of the next
                frame to be processed.  Useful if you
                don't want every frame to be a key-frame.



In the following command descriptions 'variable' parameters are shown
in the form of '<name>'.  From the command description it should be
obvious which ones must be variables and which can be literals.

Variables & literals are converted to the type required by the
command when they are accessed. For example, if an integer was
required then variables/literals with these values would all return
an integer value of 34 :

        34
        34.1
        "34fred"

If a specific type of variable/literal MUST be used then the command
description will make that clear.


**************************************************************
The following commands can only appear at the outer level of a
program.  They can not appear within procedures or controllers.


FRAMES                                FRAMES

    A FRAMES command should be the first of the program.
    It tells SCRIPT4D how many times it should loop through
    the program.

    Syntax:
            FRAMES  <number>

    Where <number> must be an integer literal.


TABLE                                 TABLE

    TABLE commands declare an 'array' of values that can be
    accessed at run-time.

    Syntax:
            TABLE  <name>  <value>...  END

    <name> must follow the rules for a variable name.
    As many <value>s as required can be specified.  Both literals
    and variables can be used.  In the latter case the value
    contained in the variable when the table is accessed will be
    used.

    Example:
            TABLE  table1  12 45.7 tiltangle "90" END

    See the CHOOSE command for more details.


SMOOTHER                             SMOOTHER

    SMOOTHERs are used to declare a sequence of values that
    progress smoothly from one limit to another in a given
    number of steps.

    Syntax:
            SMOOTHER <name>  <from>  <to>  <steps>

    <name> follows the rules for a variable name.  <from> &
    <to> must be integer or floating-point, literals or
    variables.  <steps> must be an integer literal or variable.

    Example:
            SMOOTHER twist  -20  20  11

    Via the SMOOTH command (see later) this would generate values
    that vary from -20 to 20 in 11 steps.  The value at step 1
    would be -20, that at step 6 would be 0 and at step 11 would
    be 20.  Steps less than zero and beyond the number specified
    (11 in this case) can be used - see 'Using Smooth' later.


TO / END                              TO / END

    TO & END are used to name and delimit a procedure.
    There are two command blocks within a procedure, SETUP &
    EXECUTE, either but not both of which are optional.

    Syntax:
            TO  <name>
                SETUP
                    .
                    .commands
                    .
                END
                EXECUTE
                    .
                    .commands
                    .
                END
            END

    <name> must follow the rules for a variable name.

    See the 'START' command.


AT / END                              AT / END

    AT & END delimit a controller block and specifies at which
    frame(s) the controller is executed.

    Syntax:
            AT  <frameno>...
                .
                .commands
                .
            END

    <frameno> must be an integer literal.  More than one frame
    number can be specified.

    Example:
            AT  2  7  22  16
                START kick
            END


*************************************************************
The following commands can only appear within a procedure or
controller.


SCRIPT COMMAND                        SCRIPT COMMAND

    A SCULPT script command is generated by enclosing the
    command in single quotes.  In fact, any string can be
    output by this method.

    Syntax:
            '...text...'  <parameter>...

    Parameters enable value substitution within the text string.
    Such substitution occurs in the manner of a C language
    'printf' function.

    For example, the following:

        param1 = 45
        param2 = 1.23
        param3 = "34fred"
        'One %d  Two %f  Three %s' (i) param1 (f) param2 (s) param3

    would result in an output of:

        One 45  Two 1.23  Three 34fred

    The %d, %f & %s formats will be those most commonly used. You
    can, however, use any legal conversion specification that may
    appear in a C 'printf' format string provided they match the
    supplied parameter type.

    Note that it's mandatory to force the type of the parameter to
    match the required format, whether or not it already has the
    appropriate type:

        (i)  forces to integer
        (f)  forces to floating-point
        (s)  forces to string


CHOOSE                                CHOOSE

    Selects a value from a table.

    Syntax:
            CHOOSE  <name>  <entry>  <result>

    <name> must be the name of a previously declared table.
    <entry> is a variable or literal that specifies which entry
    in the table to retrieve, starting at 1.  <result> is the
    variable that will take the selected value.

    Example:
            CHOOSE  table1  4  tilt

    See 'Assignments' for another way of coding this command.


SMOOTH                                SMOOTH

    Calculates a value from a sequence defined by a SMOOTHER
    declaration.

    Syntax:
            SMOOTH  <name>  <step>  <result>

    <name> must be the name of a previously declared smoother.
    <step> is a variable or literal that specifies the step for
    which a value will be calculated.   <result> is the variable
    that will take the value.

    Example:
            SMOOTH  twist  twiststep  twistangle

    See 'Using Smooth' for more details.

    See 'Assignments' for another way of coding this command.


Assignments                           Assignments

    A direct assignment is of the form:

        <dest>  =   <source>

    <dest> must be a variable,  <source> can be a variable or
    literal of any type.

    Arithmetic assignments are of the form:

        <dest>  +=  <source>
        <dest>  -=  <source>
        <dest>  *=  <source>
        <dest>  /=  <source>

    These perform the appropriate operation on <dest> & <source>
    and put the result in <dest>.

    For example, the commands:

        size = 20
        diff = 5
        size /= diff

    would result in 'size' having a value of 4  ( 20/5 ).

    <dest> must be a numeric variable.  <source> can be a literal
    or variable but must be numeric.  Note that <dest> always
    retains its type.

    Selection assignments are of the form:

        <dest>  @=  <name>  <step>

    where <name> is a TABLE or SMOOTHER name.  <dest> takes the
    value of the <step>th entry in the table or smoother.  This
    is an alternative method of coding SMOOTH & CHOOSE commands.

    Example:
            tilt  @=  table1  4


JOIN                                  JOIN

    Concatenated strings.

    Syntax:
            JOIN  <this>  <onthis>

    Both values are, if necessary, converted to strings and
    then <this> is appended <tothis>.  The result is placed
    in <tothis>.

    Example:
            JOIN  "+Lid"  object


EXIT                                  EXIT

    Used to immediately terminate execution of a procedure for
    the current frame.

    Syntax:
            EXIT


START                                  START

    Activates a procedure for subsequent execution.

    Syntax:
            START  <name>

    <name> must be a procedure name.

    A START command will clear any suspended or frozen state
    of the named procedure and execute its SETUP block (if any).

    STARTs would normally be used within controllers.  If however
    a procedure called A (say) STARTs procedure B then B will execute
    in the current frame if it appears after A in the program and
    will not execute until the next frame if it appears before A
    in the program.


DO                                    DO

    Executes a procedure immediately.

    Syntax:
            DO  <name>

    <name> must be a procedure name.

    The EXECUTE block of the named procedure is executed.
    No notice is taken of any suspended state nor is it cleared.
    A frozen state could be cleared if execution of the procedure
    causes its freeze count to decrement to zero.


SUSPEND                                SUSPEND

    Suspends a procedure for a given number of frames.

    Syntax:
            SUSPEND  <name>  <suspendcount>

    <name> must be a procedure name.  <suspendcount> must be a
    numeric literal or variable.

    Before a procedure is executed a check is made to see if it is
    suspended.  If so, the suspend count is decremented by 1 and if
    it has not reached zero execution of that procedure is skipped.

    Example:
            SUSPEND  eyeroll 16


RESTART                                RESTART

    Activates a suspended procedure &/or thaws a frozen procedure.

    Syntax:
            RESTART  <name>

    Example:
            RESTART  eyeroll


FREEZE                                FREEZE

    FREEZE enables the procedure in which it occurs to be
    'frozen' in a particular state for a given number of
    frames.

    Syntax:
            FREEZE  <freezecount>

    <freezecount> is a numeric variable or literal.

    We'll use a modified version of the 'blink' procedure
    as an example:

        TO blink
            ...
            EXECUTE
                blinkangle @= blinking blinkstep
                 /* ...commands to rotate eyelid by 'blinkangle'... */
                IF blinkstep = 7
                    FREEZE 5
                ENDIF
                blinkstep += 1
                IF blinkstep > 12
                    SUSPEND blink
                ENDIF
            END
        END

    At the 7th step of the blink (ie. when the eye is closed)
    the procedure is frozen for 5 frames.  Execution of FREEZE
    at this point causes the freeze-count to be set to 5 and
    the remaining commands of the procedure to be skipped.
    Thus blinkstep remains at 7.

    In subsequent frames, 'blink' is executed and, again, the
    eyelid is rotated to the closed position.  The FREEZE
    command will execute and provided the freeze-count is zero
    then so will the rest of the procedure.  Otherwise the
    freeze-count is decremented and the remaining commands of
    the procedure are skipped.

    By this method the rotation of the eyelid remains fixed
    because 'blinkstep' is not incremented while the procedure
    is frozen.

    Note that a RESTART will remove a FREEZE.


IF / ELSE / ENDIF                     IF / ELSE / ENDIF

    These provide for basic conditional processing.

    Syntax:
            IF  <condition>
                ...commands...
            ENDIF
        or
            IF  <condition>
                ...commands...
            ELSE
                ...commands...
            ENDIF

    <condition> is a simple comparision of two variables/literals.:

        A  <  B        less than
        A  =  B        equal to
        A  >  B        greater than
        A  != B        not equal to

    Example:

            IF  longdelay = 1
                FREEZE 12
            ELSE
                FREEZE 4
            ENDIF




==================================================================
USING SMOOTH
==================================================================


The idea of SMOOTHER & SMOOTH is to aid in the animation of objects
that are to move in an apparently smooth manner from one state to
another by simulating acceleration & deacceleration from & to rest.

Note that this applies to both rotational as well a spatial movement.

The following programs show three ways of using these commands to
get different effects.  You'll have to key these progs yourself!
In each case execute the program with a command of the form:

        SCRIPT4D  <progname

thus defaulting output to the screen for easy viewing.
These programs do not generate SCULPT script commands!


Program 1.  Moving from A (at 0) to B (at 500) in 20 steps.

This reqires a SMOOTHER specifying the limits of movement (0 and 500)
and the number of steps (20).


    FRAMES 20

    SMOOTHER move 0 500 20

    TO move
        EXECUTE        /* remember: 'frame' is pre-defined */
            SMOOTH move frame position
            'Frame %d,  move to %d' (i) frame (i) position
        END
    END

    AT 1
        START move
    END

    END





Program 2.  Moving from A to B and back to A in 19 steps

Similar to program 1 with the exception that the move from A to B
has to be done in 10 steps.  Thus the SMOOTHER is declared as 10
steps but SMOOTH accesses 19  -  1 TO 10 move from A to B, 11 to 19
move from B to A.

We need an odd number of steps to ensure the middle one (10 in
our case) results in the exact location of B.


    FRAMES 19

    SMOOTHER move 0 500 10    /* ie. move there in 10 steps */

    TO move
        EXECUTE
            SMOOTH move frame position
            'Frame %d, move to %d' (i) frame (i) position
        END
    END

    AT 1
        START move
    END

    END


Program 3.  Bounce down from B to A and back again in 19 steps

For the same reason as above this also needs an odd number of steps.
In order to achieve a bounce we must specify a SMOOTHER such that the
bottom of the bounce is half-way between the limits.  In addition, at
the half-way point we must increase the current step number by the
total number of steps in order to access the upward motion of the
bounce.


    FRAMES 19

    SMOOTHER bounce 500 -500 19  /* A is half-way between 500 */
                     /* and -500 */
    TO bounce
        SETUP
            step = 1
        END
        EXECUTE
            SMOOTH bounce step position
            'Frame %d, move to %d' (i) frame (i) position
            IF step = 10        /* half way point so.. */
                step += 19      /* going up! */
            ELSE
                step += 1
            ENDIF
        END
    END

    AT 1
        START bounce
    END

    END


************************************************************************
END OF DOCUMENTATION FOR VERSION 1.00