Ref:
https://news.povray.org/povray.general/thread/%3Cweb.69500a6feff8ac8317bac71e8ffb8ce3%40news.povray.org%3E/

Paul Bourke's slit-camera post made me remember something I thought about when I
experimented with slit-cameras and with in scene audio generation.

In an animation a clock runs from [0,1]. Lets say we animate at 30 fps and want
synchronised sound written by POV-Ray. You start a mini animation for the
duration of one frame with a frame local clock going [0,1]. For audio you chop
it up into 441000/30 audio frames. Synthesise the sound and writ the sound
bits'n'bytes to wav file. This can easily be done with the SDL.

In slit-camera applications there are multiple movements. It is like recording
an animation in time to a single frame. The slit shaped[1] shutter moves in some
direction, lets say left to right. The an object in a scene also moves. The
camera itself also moves. Currently in POV-Ray this all together requires
creating an animation and stitching together the slit parts of images.

It would be nice if there also was a build in frame local clock for animation.
The slit above would move along the image resolution in the frame_clock period
[0,1] in horizontal direction. Only the pixels that are under the slit are
written to file. At the same time one can move an object around using the
frame_clock in the same way it is done with the global clock. The whole camera
idem.

The slit-cam was just the inspiration. The most obvious use case would be
motion-blur. Attach a frame_clock to an object and it will be rendered at
multiple positions within a single frame.

A more esoteric use case would be temporal AA for smooth animations. In an
animation one could generate in between frame samples for AA for objects that
move but have no motion blur set. One could even get AA samples from the future.
The temporal sample depth could depend on the objects speed, or camera speed.

What about animated textures in this context?

Things that could be handy in a 4.0


[1] There is no reason why the slit shutter should be a line. It can be a pixel
wide circle that opens from some "centre point", or even a animated spline that
only covers part of the "film".

On a side note, as animation is discussed. Does POV-Ray use separate R-Trees for
static objects and dynamic objects (with clock) in an animation? I tried this in
simple 2D animation, it saved me from reparsing/filling the static tree for each
frame.

ingo

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