Le 15-12-17 17:23, Sven Littkowski a écrit :
> Hi,
>
> I admit, I never worked with fog or media before, and thus I don't
> really even know, what exactly to look for in the help file. When
> looking up there for FOG, I did not see what I need.
>
> Thus I am asking here for some starting advise.
>
> My intention is, to create a spherical object that appears like a
> blurred fog, wish shades of glowing orange inside. There is no shark
> outside edge. Just imagine a glowing, but relatively dim sun. I wonder,
> if FOG or MEDIA can do the trick, but need here some advises what
> exactly to look for inside the Help file. Thanks.
>

fog is not what you need. It can't be shaped in any way.

What you need is media.
As you want a glowing thing, emissive media seems to impose itself.
You probably don't want your glowing media to fill the whole scene, so, 
you need to contain it in something. A good shape, in your case, is the 
sphere.
Here's a minimal example:

sphere{
	0, 1
	pigment{rgbt 1} //make it totaly invisible
	hollow // enable it to contain your media
// the "magic" start here

	interior{
	 media{ emission 1 // adjust as needed
	 density{ spherical }
// start at 1 at <0,0,0> and drop to zero at radius 1
	}

	scale Dimention
	translate Location
}

This will give you a spherical shaped area of luminous gray to white 
media at the origin that you can scale as wanted, then, translate/move 
to the desired location.

If you create the sphere elsewhere, the media pattern will NOT be placed 
adequately.

If you scale, the media effect will change proportionately.
The value for emission can be a colour and it's value is not limited to 
the 0..1 range.
emission<10, 100, 1000> is legal as is emission<-1, 1, 1>

The pattern used can have a color_map that can change the effective colour.

If you add some turbulence to the pattern, you need to make the 
containing sphere larger: turbulence 0.5 need a sphere's radius of about 
1.5, otherwise, part of it will be clipped.

If you use radiosity, adding "media on" in the radiosity block will 
allow that media to illuminate it's surrounding. In a normal scene, you 
need to add an actual light_source to have it shed any light around. 
Beter to use an area_light in this case.




Alain

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