In article <chsckk$r7i$1@chho.imagico.de>, chr### [at] gmxde says...
> Antonio Ferrari wrote:
> > [...]
> > 
> > - the results that can be reached seems very poor, and in any case are only
> > a rough approximation of BSSRDF real results;
> 
> To be frank this argument shown quite well the misconception you have 
> about this effect.  POV-Ray scattering media is much more 'real' than 
> any commonly used subsurface scattering trick you find advertised in 
> other programs.  The point is of course these tricks can be much faster 
> than a full media simulation but the above sentence as you wrote it is 
> simply an inversion of reality.
> 
Speaking of reality.. There is 'the right way' and there is the 
'practical way'. Sometimes it simply isn't practical to do things the 
'right' way. A good example would be using an organic model design by 
someone else. There is no 'practical' way to make sure that the model is 
solid, especially if you used it for animation, where each frame runs the 
risk of added unexpected holes in the object. Media cannot function with 
such uncertainty to produce subsurface scattering. Not without applying 
an insane amount of impractical work into testing the media on every 
frame, then tweaking each frame of that model to 'fix' the problem. There 
may even be circumstances where you 'intend' to produce cutaways or other 
effects that may make the use of media nearly impossible for that 
application. You would want sss on the parts that are not cut away, but 
media and sss absent from the part you cut into. You can't do that in any 
practical sense with media. I don't think that for some specific cases 
'fast' with respect to the algorithm is the point, so much as that using 
media in some circumstances is simply far more complicated and time 
consuming to use than stimulating the effect.

This may be a hobbyist program, but some people would like to use it for 
more practical applications. That isn't feasible when you adhere strictly 
to 'do it the correct way or not at all' ideas. For most uses of media 
that philosophy is perfectly reasonable, for this specific use.... it is 
questionable imho. For it to be practical requires a dependence on 
everyone else making a product to 'get it right' as well and they have no 
incentive to cater to POV-Ray's limitations, even if we see it the other 
way around. I think it would make a simpler and easier option for some 
applications. Those that want to do it 'right' can still do so and good 
for them. Anyone else can save time and aggravation by doing it the other 
way.

-- 
void main () {

    call functional_code()
  else
    call crash_windows();
}

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