<ber### [at] inamecom> wrote:

>  > What about cloth simulation *requires* this? It could easily be kept
>  >  as  a persistent object, like the particle_system patch, or have
>  > data stored  in a temporary file, like radiosity or photon mapping.
> 	This assumes you're doing an animation and want the cloth to evolve from 
> frame to frame.

No, it doesn't!


> I was speaking more of several test renders of the same scene for 
> which having the cloth computed once ond for all is clearly better.

It certainly is (unless you are adjusting the cloth, of course...). And 
there is no problem with storing it to a file and using the file for 
test renders, or even with quitting and restarting POV-Ray.


> 	Unless I'm very much mistaken, you do recompute the particle_system for 
> each render don't you? (I don't mean each frame in an animation here) 

Yes, I do, because I haven't implemented the save_file and load_file 
features yet. But it is certainly possible to save the state to a file 
and restore it when needed, it just needs to be implemented.


> This is too slow in my opinion, so you need to be able to perform the 
> cloth simulation once and save the result in a file (a mesh is the most 
> logical form of output here, though not the only one).

But you can't continue the cloth simulation from mesh data...the most 
logical output would be to save the whole cloth simulation. If it was an 
external utility and you were producing an animation, you would have to 
output a lot of POV scenes and then render them, instead of running a 
simulation while the animation progresses. If it is an internal patch, 
it doesn't make sense to have it save to a POV file, because that means 
you will always have to run it from the very beginning.


> Maybe the particle system renders faster than cloth, otherwise I 
> would argue that particle systems should probably be implemented as 
> an outside utility too...

And I don't see what rendering time has to do with any of this...it will 
render at the same speed whether you use a patch or an external utility. 
Actually, it may be possible to optimize a patch for even more speed...


> 	I'll return the question about height-fields to you: what is the 
> difference between hfs and cloth that would justify the cloth to be 
> generated in pov while the hf is generated by an outside program? 

Um, well, I usually generate my height fields with POV-Ray...
The difference between height_fields and cloth? Cloth interacts with the 
objects of the scene, that information is required in order to generate 
the cloth, so it makes sense for it to be specified as part of the 
scene. Height fields are a fixed element that don't usually depend on 
anything in the scene.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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