"Dave Blandston" <nomail@nomail> writes:

> That's interesting - I had forgotten that
> frame_number even existed because I
> got used to using clock years ago, but I can see
> that frame_number would be more
> appropriate under some circumstances, possibly
> including this one. I did in fact
> have to include some code to convert number of
> frames generated to time elapsed
> so using frame_number would be exact instead of
> within 1 / framerate / 2. The
> beat markers will be in milliseconds which would
> have to be converted to
> frame_numbers though so it's a trade-off either
> way. Thank you for the excellent
> suggestion!

In case someone doesn’t know, the /POV-Ray Reference/ has something to
say about this
(<http://www.povray.org/documentation/3.7.0/r3_2.html#r3_2_1_2>):

> 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.

[...]

> 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.

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