statto wrote:

> Explaining why might make my question clearer: some friends and I
> were discussing what it would look like if you could take a film with
> a camera so fast that you could watch the progress of light across a
> room. I want the light to ooze slowly out of the lights and over
> objects, and so I want to terminate any ray which is longer than a
> distance ct, where c is the speed of light and t the (short!) time
> since the start of the film.

I think there is a fundamental problem with this approach,
namely that POV-Ray does not trace from the light sources
forward but from the eye backwards. So, terminating rays
doesn't really have the effect of light oozing anywhere.

What you might do however, is to create an animation with a
light source which increases in range (using rather drastic
settings for fade_distance and fade_power, you should be
able to get sharp cutoffs).

Although this may look similar to what you expect, it is
however not physically correct because it does not take into
account the time for the light to travel from the object to
the camera.

Furthermore, you may also need to take into account that
your film material moves at relativistic speed :-P

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