nemesis wrote:
> andrel wrote:
>>> I think is that ATM GPU's are useful for trangulations and
>>> that the  result is near real life. As far as I have heard the
>>> rendering is less physical correct and more is faked. I though they
>>> were a bit lacking in multiple reflection and refraction, in media
>>> and possibly also in versatility of procedural textures. I am not a
>>> gamer, so I don't actually know for sure.
>>>
>> So, point me to where I talked exclusively about game tech.
> 
> "less physical correct", "lacking reflection and refraction", "lacking 
> media" and "lacking procedural textures" are all indeed game tech 
> limitations (for now) that don't show up at all in the "physically 
> correct" path tracer running on GPU I linked to.
> 
>> But let me try to explain again: what you pointed at and other things 
>> I have seen so far is that GPUs are used for a limited set of 
>> primitives only, modelling a subset of physical behaviour. Even if 
>> they claim to be physically accurate in practice they aren't
> 
> GPU's don't claim anything.  General purpose algorithms making use of 
> their sheer math processing power do.
> 
> I thought by physically correct you were talking about materials or 
> light propagation behavior, not every model being made of from polygons.
> 
>>  Again what I have seen and understood is that up till now POV is more 
>> physical complete (disclaimer: I have not seen everything that is out 
>> there.). Hence POV still has a place.
> 
> and I hope that place is a GPU.
> 
>> In order to get more 'realistic' games the GPUs have been optimized to 
>> render textures and fake reflections and shadows. They can be used as 
>> FPU replacement for certain tasks, but they are not perfect for 
>> general processing (yet). That is as far as I know. There may have 
>> been significant advances that I have missed because I am not a gamer 
>> and hence do not follow the developments closely.
> 
> I'm not talking about games at all.  I only hinted at the fact that 
> several other raytracers are beginning to use the GPU for their 
> calculations, including full raytraced reflections, refractions, 
> mesh-based lighting etc.  They are not using the GPU as a mere game 
> scanline engine,  they are just general purpose programs (actually, 
> parts of it) running on GPU.
Lets just say that.. It may be feasible to do in an hour what takes days 
now, using a GPU, for POVRay, when it was using prior CPUs, that didn't 
have the bit depth for floats that modern ones do. But I agree with 
Andrel's general assessment, based on what I have seen and read, that, 
*in general* too many things are still done using cheats, because the 
GPU can't handle them, and you *may* find yourself running into 
precision issues, when trying to use some GPUs.

Now, that said, you *could* allow for a "minimum" requirement in that 
respect, and get stuff as good or better than we see on a cheap machine 
now, possibly. Though, that is a pure guess. You could then "allow for" 
some sort of computable scaling of settings, where if the GPU allowed 
larger floats, you could adjust to get a *better* final. Problem is, 
most of that parameters are stuff that is bloody hard to get right when 
you *know* the machine you are using, never mind if you had to have the 
parser "update" them to match a better GPU.

All of which become irrelevant, if AMD's idea takes wing and the GPU 
becomes part of the CPU, making the difference between the "internal" 
floats, and the "external" GPU floats completely bloody meaningless. We 
may see GPUs become a sort of "enhanced process" loaded with stuff the 
inbuilt doesn't handle, instead of the main focus of this whole thing. 
The end result is likely that the difference between an AMD compliant 
POVRay and one for GPU will be zip, zilch, and nada.

-- 
void main () {

     if version = "Vista" {
       call slow_by_half();
       call DRM_everything();
     }
     call functional_code();
   }
   else
     call crash_windows();
}

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