In article <3a79f7f5@news.povray.org>, "Alessandro Coppo" 
<a.c### [at] iolit> wrote:

> DLLs are binary modules which contain code loadable and callable at 
> runtime. Windows has DLLs. Linux, BSD, Solaris etc.etc. have shared 
> libraries (look into /usr/lib for all those .so files...). VMS has 
> shared libraries. I presume that Mac's have a similar mechanism, OSX 
> being a Mach kernel + GNU tools is in the U*X pack.

However, they all do things in their own platform/OS-specific way, so 
you still have to (re)write code for handling the libraries for each 
platform. Handling the Linux/BSD Unix/Mac OS X group might not be too 
difficult, but add in Mac OS versions before and including 9.1, and the 
various Windows versions, and other OS's, and you have a problem. There 
is no standard C mechanism for doing this kind of thing.


> A proposal for a custom compile: create a multithreaded engine which 
> can take advantage of multi CPU boards (render a different set of 
> lines on each CPU and merge the result.). The speedup would be almost 
> linear (what about a quad 1GHz Athlon PC?)

This is a different matter completely...and very difficult to do 
properly, because POV-Ray was never designed to have multiple threads. 
Even if you ignore cross-platform differences, you have problems getting 
it to share data among the different threads properly (for example, 
radiosity, maybe photon maps, etc.). If you don't do this, you end up 
with visible artifacts where parts of the image rendered on different 
threads join together. You would need to do a lot of reworking on the 
source code to get it to work at all.
I think there is a multithreaded version of POV-Ray available (PVM-POV), 
but I don't know much about it, and I don't think it works well with 
radiosity. I don't even know if it does things on a per-image basis, it 
may just distribute different frames to different processors, or give 
different chunks of the image to different processors.

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

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