"KalleK" <kal### [at] gmxde> wrote in message news:3cc2d464$1@news.povray.org...
>
> I tried to set falloff and radius the same but in difference to spotlight,
> this doesn't make my cylinderlight sharp. What does radius and falloff
mean
> when used with cylinder? The help says, they have the same function as
with
> spotlight, but there seems to be a huge difference concerning falloff
> together with radius.

tightness 1, or a very small number. I've used less than 1 even though the
Doc says 1 to 100. Remember that tightness 100 concentrates toward the
radius fading the falloff, tightness 1 concentrates toward falloff diameter.
For cylinder lights this is a bit less straightforward to me, and others too
apparently, since the values for radius and falloff don't result in the same
area of projection. I can't recall what, if any, explanation is for the
differences except maybe it has to do with the cone angle versus cylinder
being a diameter. 0 to 1 (something) perhaps, instead of 0 to 360 degrees?
But I'm conjecturing. I notice it isn't stated in the Doc.

> By the way, I'm using 3.5 beta, there's a note in the helpsection 6.5.7.3
> Cylindrical Lights that says:
> "You should keep in mind that the cylindrical light source is still a
point
> light source. The rays are emitted from one point and are only constraint
by
> a cylinder. The light rays are not parallel."
> Maybe it could be added that one can in fact make them parallel by using
the
> keywort parallel.

I thought it was said someplace... maybe just inferred there where you
mention it since the following section is about parallel lights. Either that
or I could be thinking of someone commenting it into a scene file, example
with 3.5 or elsewhere.
Anyhow that still only affects the shadows, I think, and not the actual
light radius.

bob h

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