Tim Nikias v2.0 wrote:

> SNIP
> 
>>I don't see why implementing it would make things
>>worse as you don't _have to_ use it allways - except that it needs to be
>>implemented ;) It would simply make POV-SDL more versatile. But maybe
>>POV-SDL will someday evolve to a form where this can be done easily.
> 
> SNIP
> 
> Just to comment on this lone part of the discussion: I don't think that
> making assumptions for the User is versatile. It often leads to places where
> the User has to guess/assume what the Programm is assuming and
> counter-effect that. POV-Ray, to me, was always about scripting what you
> need and want. If I want a special effect, like photons, I have to put it
> there, especially since photons can cause a load of data which would slow
> down rendering even if not in sight. I was always glad that POV-Ray "ships"
> with the most basic default settings, and assumes nothing, so that I know
> *exactly* what's happening, when I view the code.

You are totally correct and I agree that the user should allways have 
the control. BUT:

Basically photon mapping is an effect in the same way as caustics, 
specular reflection, reflection etc. It uses different method and might 
cause considerable slowdown even when not visible, but it is still an 
effect and it can replace caustics, for example. And if caustics can be 
included in material definition, then why not photons as well? I simply 
don't understand why photons should be treated differently than the rest 
of the "effects".

And: if you assign photons to a material, why wouldn't you know what is 
happening? Why would you need to assume anything? If you assign that 
material to an object, that object will be used as photon target. Simple.

There are worse examples of guessing/assuming: using radiosity you are 
making every object emit light unless you alter the default ambient 
value. So not all default values are intuitive :)

> Oh, and "efficiency" has nothing to do with speed of PC's. If you don't need
> calculations for effect, don't do them. That's efficiency: save where
> possible.

Yes, but photons, for example might contribute to the visible part of 
the scene even when the object itself is not visible. So efficiency 
would be to test if the object affects to visible part and save the 
calculations if not. I have to admit I don't know exactly how photon 
mapping in POV-Ray works so it might be doing this kind of checking 
allready.

PS. I'm not trying to complain, I just proposed a feature that might be 
of some use to some people. To me, atleast ;-)

Severi S.

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