Negative atmospheric density on spotlights

Mouse

So spotlights have an atmospheric density property. Typically you assign this property a value between 0 and 1.


@Kasharic and @Mephilles have discovered that you can also assign negative values.

With positive values atmospheric density gives the light coming from spotlight a glow that's of the same colour as the spotlight. Effectively it decreases contrast.

From left to right the values in this pic are 10, 1 & 0.1

With negative values atmospheric density gives the light coming from the spotlight a glow that's a different colour than the spotlight. Effectively it increases contrast.

From left to right the values in this pic are -0.1,-1 & -10

I'm not sure what the exact relationship between the colours is:
- white (255;255;255) -> black (0;0;0)
- red (255;0;0) -> blue (0;0;255)
- green (0;255,0) -> purple (255;0;255)

I've had a play with negative atmospheric density in fusion where I've mostly just negated the existing values and made no attempt at tweaking:

Unloading (in editor)
Positive atmospheric density



Negative atmospheric density



Shortcut (in editor)
Positive atmospheric density


Negative atmospheric density


Observation (in game)
Positive atmospheric density


Negative atmospheric density

A rough guide for using negative atmospheric density
- It can look good, but you need to use it subtly
- With positive atmospheric density values between 0 and 1 work the best. With negative atmospheric density values between 0 and -0.2 work the best (the spotlight in Observation uses a value of -0.01)
- It looks the best when there's a decent amount of secondary lighting and the room is relatively well lit to begin with. It negative atmospheric density can look utterly terrifying when it's coming from the main light source in a dark room
- If you're going to add it to your level do it last as a final tweak to the lighting, because the quality of the effect depends entirely on the rest of the lighting in the room

The_Welsh_Wizard

This is cool.

Vetinari

Does this effect only work if the player has atmospherics enabled?

Mouse

Vetinari wrote: »

Does this effect only work if the player has atmospherics enabled?

Yep. Without atmospherics turned on you just have standard spotlight.
Which is another reason it should only be added in a final pass on the lighting.