About rainbow - I did never enable the dispersion for fog. - But it used for?glimpse wrote:don't see anything 'bug' like except Your incompetence with render engine, Sorry for straight forward answer.
What You're trying to achieve, Nuno? You want to split the light & see the rainbow spectrum in the fog? =)
my rig is on the road, but I'll give a look into this, 'cos You're messing with this case way too long..
Please, post REFERENCE image of what You want to get.
Ok.Daniel wrote:I think you need to at least understand the basic physics behind these phenomena before trying to tackle these effects.
First of all, the image you posted looks to be light coming from a projector, so the source of the light is multicoloured, it's not being split by another medium. Secondly, fog is nowhere near dense enough a material to split light. It has to travel through something like glass or diamond, and at an angle no less, if you want to see the spectrum of light come out the other end.
The light source (laser) multicoloured isn't needed but yes it's a example. The disperison is for prism or diamond only. 
