CD Actual 22/PC Actual CD 22.iso/SHARE/prog/POVRAY/CLOCKMOD.ZIP/CLOCKMOD.TXT

Text File | 1997-06-24 | 13.9 KB | 388 lines

**************************************************************************
**************************************************************************
        CLOCK MODIFIER INCLUDE FILE FOR PERSISTENCE OF VISION 3.x
**************************************************************************
**************************************************************************

Created by Chris Colefax, 24 June 1997

1.0  INSTALLATION
2.0  QUICK START
3.0  CLOCK TYPES
        3.1  Accelerate
        3.2  Decelerate
        3.3  S-Curve
        3.4  Triangle
        3.5  Jump
        3.6  Bounce
        3.7  Oscillate
        3.8  Wave
        3.9  Recoil

4.0  CLOCK MODIFICATION OPTIONS
        4.1  clock_start & clock_finish
        4.2  clock_repeat
        4.3  clock_strength
        4.4  clock_combine

5.0  USING THE CLOCK MODIFICATION PREVIEW
        5.1  graph_continuous
        5.2  graph_thickness
        5.3  graph_smoothness

6.0  USING THE mclock VARIABLE
        6.1  TRANSLATING OBJECTS
        6.2  OTHER TRANSFORMATIONS
        6.3  PIGMENTS AND OTHER ATTRIBUTES

7.0  CONTACTING THE AUTHOR

**************************************************************************


1.0  INSTALLATION
**************************************************************************
The Clock Modifier consists of two files, ClockMod.inc and ClockP.inc
which should be copied to one of the directories (folders) in your POVRay
library path.  Normally this is the INCLUDE sub-directory of the directory
where you installed POVRay, so if you installed POVRay in C:\POVRAY you
should copy the ClockMod.inc file to C:\POVRAY\INCLUDE.  On a Windows 95
system, this is probably something like:

   C:\Program Files\POV-Ray for Windows\Include

On UNIX and similar systems, where filenames are case-sensitive, you may
have to rename the include files so the capitals and lowercase are as
shown above.  This will enable you to render the sample files without
modification.


2.0  QUICK START
**************************************************************************
POVRay animation is usually achieved using the clock variable. While this
concept is quite simple, it can also be very frustrating.  Even trying to
animate the most basic of scenes often requires you to know and use a lot
of complicated mathematical functions.  With the Clock Modifier include
file you can choose from a whole variety of different clock types, such
as Acceleration, Deceleration, Recoil, and Bounce, and use them to animate
objects, light_sources, etc. in all sorts of different ways.  Using a
modified clock value is as simple as declaring the name of the desired
modification, and then including ClockMod.inc, eg:

   #declare clock_type = "Wave"
   #include "ClockMod.inc"

In addition there are a variety of other options than can be used to
modify and combine different clock types.  To use any of these just add
the following line to your scene file, BEFORE including ClockMod.inc:

   #declare [variable-name] = [value]

substituting the desired variable name and value where appropriate.
The Clock Modifier include file will then create a new variable, mclock,
that can be used to scale, rotate, and translate objects, as well as
alter their pigments and other attributes, eg:

   object {MyObject
      #declare clock_type = "Bounce"
      translate y * mclock * 10}

Note that ClockMod.inc should NEVER be included at the start of a scene
(like "colors.inc" or "textures.inc").  It should only be included
after declaring the desired clock type and options.  To use the Clock
Modifier more than once in a scene, you should declare the first set of
options and include "ClockMod.inc".  Then declare the next set of options
and include "ClockMod.inc" again.


3.0  CLOCK TYPES
**************************************************************************

The Clock Modifier include file allows you to use nine different clock
types, as listed below.  To use a particular clock type, you must first
declare the clock_type variable as the name of the desired type.  Note
that you only have to use the first letter of a particular type, eg:

   #declare clock_type = "O"

rather than #declare clock_type = "Oscillation".  You can preview all of
the available clock types by rendering the Preview.pov scene.

3.1  ACCELERATE
***************
This clock type starts out slow and then gradually speeds up.  This is
very useful for animating moving objects.  You can adjust the rate of
acceleration using the clock_strength option (see below).  See the
Anim1.pov scene for an example of this clock type.

3.2  DECELERATE
***************
This clock type starts out fast and then slows down.  You can adjust
the rate of deceleration using the clock_strength variable.  See the
Anim1.pov scene for an example of this clock type.

3.3  S-CURVE
************
This clock type is like a combination of acceleration and deceleration;
it starts out slow, speeds up, and then slows down again.  It had many
uses, such as smoothly changing the colour of an object (see the Anim3.pov
scene for an example).

3.4  TRIANGLE
*************
This clock type rises and then falls again, with sharp changes of
direction.  It can be used to make objects pulsate (see the Anim2.pov scene
for an example).

3.5  JUMP
*********
This clock type is similar to the Triangle clock type, but it slows down
as it rises, and then speeds up again as it falls (the change of direction
at the top is smooth).  The clock_strength option can be used to adjust
the rate of acceleration/deceleration.  See the Anim3.pov scene for an
example of this clock type.

3.6  BOUNCE
***********
As the name suggests, this clock type can be used to make objects bounce.
It starts out high, than falls and bounces back.  The clock_strength option
can be used to adjust the rate of acceleration/deceleration.  See then
Anim2.pov scene for an example of this clock type.

3.7  OSCILLATE
**************
This clock type starts at 0, then rises to 1.  It then falls to -1, and
rises again to 0.  It can be used to oscillate all sorts of objects (see
the Anim2.pov scene for an example).

3.8  WAVE
*********
This clock type is similar to the Oscillate clock type, but it starts at 0,
rises to 1, and then falls back to 0.  See then Anim1.pov scene for an
example of this clock type.

3.9  RECOIL
***********
This clock type can be used to animate all sorts of recoiling objects, such
as firing guns, etc.  The clock_strength option can be used to alter the
rate of recoil.  See the Anim3.pov scene for an example of this clock type.


4.0  CLOCK MODIFICATION OPTIONS
**************************************************************************
The nine basic clock modification types can be altered using the following
variables.

4.1  clock_start & clock_finish
*******************************
Normally the POVRay internal clock starts at 0 (at the beginning of the
animation) and ends at 1.  If you are using different clock values, you
can set these using the clock_start and clock_finish variables, eg:

   #declare clock_start = 0
   #declare clock_finish = 100

You can also use these variables to make a particular modification occupy
only part of a scene, eg:

   #declare clock_type = "Accelerate"
   #declare clock_start = .7

will only start accelerating 70% of the way through the animation.

4.2  clock_repeat
*****************
You can use this option to make a particular modification repeat itself
during the course of an animation, eg:

   #declare clock_type = "Recoil"
   #declare clock_repeat = 10

could be used to make a cannon fire 10 times.

4.3  clock_strength
*******************
This option can be used to alter the rate of acceleration/deceleration of
the following clock types: Accelerate, Decelerate, Jump, Bounce and Recoil.
The default value is 1; numbers larger than this will increase the rate,
while numbers smaller than 1 will decrease the rate, eg:

   #declare clock_type = "Jump"
   #declare clock_strength = 2

will make the bouncing motion more apparent.

4.4  clock_combine
******************
This option can be used to combine one clock type with another.  This is
most useful when using a repeated Wave or similar, eg:

   #declare clock_type = "Wave"
   #declare clock_repeat = 10

will give 10 waves, each taking the same length of time.  If you wanted the
waves to get quicker as time passed, you could combine the above with an
Accelerate, eg:

   #declare clock_combine = "Accelerate"

The Combine.pov scene shows how this option works.  Note that if you using
the Clock Modification include file more than once in a scene, and you have
used clock_combine once but don't want to use it again, you should declare
is as "", eg:

   #declare clock_type = "Wave" #declare clock_combine = "Accelerate"
   #include "ClockMod.inc"

   #declare clock_combine = ""


5.0  USING THE CLOCK MODIFICATION PREVIEW
**************************************************************************
When using a variety of the above options (especially the clock_combine
option) it can be very useful to see a graph of the mclock variable.  You
use achieve this using the ClockP.inc file; first declare the desired
clock options, and then include the ClockP.inc file (DO NOT include the
ClockMod.inc file), eg:

   #declare clock_type = "Recoil" #declare clock_repeat = 3
   #declare clock_combine = "Decelerate" #declare clock_strength = 2
   #include "ClockP.inc"

No other cameras, lights, or objects are necessary, though the following
options can be used to control the clock preview.

5.1  graph_continuous
*********************
Normally the graph is plotted using spheres.  If you would prefer an
unbroken line graph, use this option, eg:

   #declare graph_continuous = true

5.2  graph_thickness
********************
Use this option to change the thickness of the line graph, eg:

   #declare graph_thickness = .01

The default for graph_thickness is .02

5.3  graph_smoothness
*********************
Use this option to alter the number of points plotted on the graph, eg:

   #declare graph_smoothness = 250

The default is 100.  Increasing this option will make the graph more
accurate, and is useful when you have a very complex graph (eg. many
repeated oscillations).


6.0  USING THE mclock VARIABLE
**************************************************************************
This section contains a basic explanation of how to use the mclock
variable to modify different objects in a variety of ways.

6.1  TRANSLATING OBJECTS
************************
Animations generally involve movement of some kind.  The simplest way
to move an object (or light_source, camera, etc.) is to use the translate
command, eg:

   object {MyObject translate <10, 10, -10>}

This will move the specified object 10 units along the x-axis, 10 units
up the y-axis, and -10 units along the z-axis.  If you wanted to animate
the object, so that it started at its current position, and then
accelerated to it's new position, you would use:

   object {MyObject
      #declare clock_type = "Accelerate"
      #include "ClockMod.inc"
      translate <10, 10, -10> * mclock}

Note that you can add translations together, so you can first create your
object at the origin, then animate it, and finally move it into the correct
position, eg:

    sphere {<0, 0, 0>, 1
       pigment {color Red}
       #declare clock_type = "Bounce"
       #include "ClockMod.inc"
       translate y * mclock * 5
       translate <10, 1, 20>}

This will create a red sphere that bounces 5 units high (up the y-axis),
and bounces on the spot located at <10, 1, 20>.

6.2  OTHER TRANSFORMATIONS
**************************
You can use mclock with rotate and scale in the same way as with
translate, eg:

   object {MyObject
      #declare clock_type = "Jump"
      #include "ClockMod.inc"
      scale mclock * 2

      #declare clock_type = "Oscillate"
      #include "ClockMod.inc"
      rotate y * 50 * mclock}

This will make the object pulsate between its normal size and double its
size, and also rotate back and forth 50 degrees around the y-axis.

6.3  PIGMENTS AND OTHER ATTRIBUTES
**********************************
In addition to the transformation above, you can use the mclock variable
with any POVRay attribute that requires a number.  An example of this is
pigments, eg. to make a flashing blue light:

   light_source {<10, 30, -20>
      #declare clock_type = "Wave"
      #declare clock_repeat = 20
      #include "ClockMod.inc"
      color Blue * mclock}

The mclock variable can also be used in the pigment, normal and finish
statements of objects, as well as when animating camera angles, etc.
Often you will want to go from one value to another, eg. changing an
object from Red to Green.  To do this, use the following commands:

   #declare clock_type = "S-Curve"
   #include "ClockMod.inc"
   pigment {Red + mclock * (Green - Red)}

As you can see, you start with the first value, and then add mclock
multiplied by the different between the two values (which is always the
second value take away the first value).  If you wanted to make an object
become less reflective during an animation, you could use:

   #declare clock_type = "Decelerate"
   #include "ClockMod.inc"
   finish {reflection .8 + mclock * (.2 - .8)}

This will change the reflection from .8 at the start of the animation, down
to .2 at the end.


7.0  CONTACTING THE AUTHOR
**************************************************************************
If you wish to contact me with bug reports, bug fixes, criticisms,
comments, suggested improvements, questions, etc. you can reach me by
email at:

   [e-mail]

or by regular mail at:

   Chris Colefax
   PO Box 110
   Kuranda, Queensland
   Australia  4872

**************************************************************************

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