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Internal animation loop, automatic output file name numbering and the ability to shell out to the operating system to external utilities which can assemble individual frames into an animation, greatly improved the animation capability. The internal animation loop is simple yet flexible. You may still use external programs or batch files to create animations without the internal loop.
Clock=n.n |
Sets clock float identifier to n.n |
+Kn.n |
Same as Clock=n.n |
The Clock=n.n option or the
+Kn.n switch may be used to pass a single float value to the
program for basic animation. The value is stored in the float identifier
clock. If an object had a rotate <0,clock,0>
attached then you could rotate the object by different amounts over different
frames by setting +K10.0,+K20.0... etc. on
successive renderings. It is up to the user to repeatedly invoke POV-Ray with
a different Clock value and a different
Output_File_Name for each frame.
The internal animation loop relieves the user of the
task of generating complicated sets of batch files to invoke POV-Ray multiple
times with different settings. While the multitude of options may look
intimidating, the clever set of default values means that you will probably
only need to specify the Final_Frame=n or the
+KFFn option to specify the number of frames. All other
values may remain at their defaults.
Any Final_Frame setting other than -1 will trigger
POV-Ray's internal animation loop. For example
Final_Frame=10 or +KFF10 causes POV-Ray to render your
scene 10 times. If you specified Output_File_Name=file.tga
then each frame would be output as file01.tga, file02.tga,
file03.tga etc. The number of zero-padded digits in the file name
depends upon the final frame number. For example +KFF100 would
generate file001.tga through file100.tga. The frame
number may encroach upon the file name. On MS-DOS with an eight character limit,
myscene.pov would render to mysce001.tga through
mysce100.tga.
The default Initial_Frame=1 will probably never have to be
changed. You would only change it if you were assembling a long animation
sequence in pieces. One scene might run from frame 1 to 50 and the next from
51 to 100. The Initial_Frame=n or
+KFIn option is for this purpose.
Note: if you wish to render a subset of frames such as 30 through 40 out
of a 1 to 100 animation, you should not change Initial_Frame or
Final_Frame. Instead you should use the subset commands
described in section "Subsets of Animation Frames".
Unlike some animation packages, the action in POV-Ray animated scenes does
not depend upon the integer frame numbers. Rather you should design your
scenes based upon the float identifier clock. By default, the
clock value is 0.0 for the initial frame and 1.0 for the final frame. All
other frames are interpolated between these values. For example if your
object is supposed to rotate one full turn over the course of the animation,
you could specify rotate 360*clock*y. Then as clock runs from
0.0 to 1.0, the object rotates about the y-axis from 0 to 360 degrees.
The major advantage of this system is that you can render a 10 frame animation or a 100 frame or 500 frame or 329 frame animation yet you still get one full 360 degree rotation. Test renders of a few frames work exactly like final renders of many frames.
In effect you define the motion over a continuous float valued parameter (the clock) and you take discrete samples at some fixed intervals (the frames). If you take a movie or video tape of a real scene it works the same way. An object's actual motion depends only on time. It does not depend on the frame rate of your camera.
Many users have already created scenes for POV-Ray 2 that expect clock
values over a range other than the default 0.0 to 1.0. For this reason we
provide the Initial_Clock=n.n
or +KIn.n and Final_Clock=n.n
or +KFn.n options. For example to run the clock from 25.0 to
75.0 you would specify Initial_Clock=25.0 and Final_Clock=75.0.
Then the clock would be set to 25.0 for the initial frame and 75.0 for the final frame.
In-between frames would have clock values interpolated from 25.0 through 75.0 proportionally.
Users who are accustomed to using frame numbers rather than clock values
could specify Initial_Clock=1.0 and Final_Clock=10.0
and Frame_Final=10 for a 10 frame animation.
For new scenes, we recommend you do not change the
Initial_Clock or Final_Clock from their default 0.0 to
1.0 values. If you want the clock to vary over a different range than the
default 0.0 to 1.0, we recommend you handle this inside your scene file as
follows...
#declare Start = 25.0; #declare End = 75.0; #declare My_Clock = Start+(End-Start)*clock;
Then use My_Clock in the scene description. This keeps the
critical values 25.0 and 75.0 in your .pov file.
Note: more details concerning the inner workings of the animation loop are in the section on shell-out operating system commands in section "Shell-out to Operating System".
When creating a long animation, it may be handy to render only a portion
of the animation to see what it looks like. Suppose you have 100 frames but
only want to render frames 30 through 40. If you set Initial_Frame=30
and Final_Frame=40 then the clock would vary from 0.0 to 1.0 from
frames 30 through 40 rather than 0.30 through 0.40 as it should. Therefore
you should leave Initial_Frame=1 and Final_Frame=100
and use Subset_Start_Frame=30 and Subset_End_Frame=40
to selectively render part of the scene. POV-Ray will then properly compute the
clock values.
Usually you will specify the subset using the actual integer frame numbers
however an alternate form of the subset commands takes a float value in the
range 0.0 <=n.nnn <=1.0 which is interpreted as a fraction of
the whole animation. For example, Subset_Start_Frame=0.333 and
Subset_End_Frame=0.667 would render the middle 1/3rd of a
sequence regardless of the number of frames.
Cyclic_Animation=bool |
Turn cyclic animation on/off |
+KC |
Turn cyclic animation on |
-KC |
Turn cyclic animation off |
Many computer animation sequences are designed to be run in a continuous
loop. Suppose you have an object that rotates exactly 360 degrees over the
course of your animation and you did rotate 360*clock*y to do
so. Both the first and last frames would be identical. Upon playback there
would be a brief one frame jerkiness. To eliminate this problem you need to
adjust the clock so that the last frame does not match the first. For example
a ten frame cyclic animation should not use clock 0.0 to 1.0. It should run
from 0.0 to 0.9 in 0.1 increments. However if you change to 20 frames it
should run from 0.0 to 0.95 in 0.05 increments. This complicates things
because you would have to change the final clock value every time you changed
Final_Frame. Setting Cyclic_Animation=on or using
+KC will cause POV-Ray to automatically adjust the final clock
value for cyclic animation regardless of how many total frames. The default
value for this setting is off.
Field_Render=bool |
Turn field rendering on/off |
Odd_Field=bool |
Set odd field flag |
+UF |
Turn field rendering on |
-UF |
Turn field rendering off |
+UO |
Set odd field flag on |
-UO |
Set odd field flag off |
Field rendering is sometimes used for animations when the animation is being output for television. TVs only display alternate scan lines on each vertical refresh. When each frame is being displayed the fields are interlaced to give the impression of a higher resolution image. The even scan lines make up the even field, and are drawn first (i.e. scan lines 0, 2, 4, etc.), followed by the odd field, made up of the odd numbered scan lines are drawn afterwards. If objects in an animation are moving quickly, their position can change noticeably from one field to the next. As a result, it may be desirable in these cases to have POV-Ray render alternate fields at the actual field rate (which is twice the frame rate), rather than rendering full frames at the normal frame rate. This would save a great deal of time compared to rendering the entire animation at twice the frame rate, and then only using half of each frame.
By default, field rendering is not used. Setting
Field_Render=on or using +UF will cause alternate frames
in an animation to be only the even or odd fields of an animation. By
default, the first frame is the even field, followed by the odd field. You
can have POV-Ray render the odd field first by specifying
Odd_Field=on, or by using the +UO switch.
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