"Slime" <fak### [at] emailaddress> 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.
>
> If you want to accurately simulate the speed of light, you want surfaces to
> remain dark until enough time has passed for light to travel the distance
> from the light source to the object, and then to the camera.
>
> So, for any point in 3D space, the time until that point should be visible
> is proportional to distance(point, light) + distance(point, camera). You can
> make a function{} that calculates this value. Then, make a texture that uses
> that function to display white where it is less than a certain threshold,
> and black otherwise. If you apply that texture to all objects in the scene,
> and change the threshold over time with the 'clock' variable, you can make
> an animation where the lit parts of the scene are shown in white.
>
> Then, it should be possible to take that video and use it as a mask for the
> original, normally textured image. This could be done in POV-Ray with some
> texture/function cleverness or just in a third party video editor.
>
>  - Slime
>  [ http://www.slimeland.com/ ]

Sounds pretty, good, but one could also multiply that pigment with existing
scene pigments.  That way, the white parts will leave the original pigment
unaffected, whereas the black bits will cancel it out.

Or something.

-Reactor

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