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The falloff value in a spotlight is the outside of the light cone. The radius
is the inside spot and the tighness defines how sharp the transition is. A
lower tightness gives a wider spot and a sharp edge to the light. It sounds
like what you want is something that will diminish the intensity of a point
light source though.
For that, you want to use light fading. This diminishes the intensity of light
the farther it is from the source. The two things to control this are:
fade_distance - how far from the light source the light fades
fade_power - the method use for the falloff. Can be 1, 2, or 3
1 is linear
2 is quadratic
3 is cubic (I assume)
This is covered in section 7.5.6.7 for reference.
-Mike
David Vincent-Jones wrote:
> I am trying to achieve in an image similar bright information lights - like
> a traffic light or a car tail-light - without coloring the entire image from
> that light.
> Falloff looks like the correct control to use but I am having a problem
> finding documentation for lights other than the spotlight. Should falloff
> reduce the intensity of the light back to the camera or just to the
> surrounding structures?
> Has anybody experience with falloff values in general.
> Thanks
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David Vincent-Jones (geo### [at] galaxynet com) wrote:
: I am trying to achieve in an image similar bright information lights - like
: a traffic light or a car tail-light - without coloring the entire image from
: that light.
There are two possibilities:
a) You want only a light source to be seen, but not necessarily illuminate
anything (like a little led or something like that). Don't put any light
source, but put an object with finish { ambient 1 }. This object will look
like it's emitting light (because it's bright even if there's not any light
source in the scene). It's also fast to render.
b) You want a light source that actually illuminates the objects very
near to it, but that diminishes very fast. Use a fading light with
a little fade_distance and fade_power set to 2 (this works a lot like real
light sources). Note that this will slow the rendering because this light
source is checked for every pixel in the scene, so if you put 1000 light
sources like this, it will be quite slow...
--
- Warp. -
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