In article <35B614C9.CEDD9B4A@dtmf.com> , Photon <pho### [at] dtmfcom>  wrote:

>I've been using Povray since the 2.x days, and I just grabbed 3.1b4
>(first new release I've touched since 3.0[12])....   I have two
>questions about this 3.1 release:
>
>1.  There is no unix beta... does this imply there will be no unix
>version period?  Or was it just that you didn't want to put out the
>source code until after the beta cycle is complete? (which doesn't make
>sense to me....)  Unix versions need to be beta tested too...


The Mac version contains the following in one of the readmes (BETANOTE.TXT), it refers
to beta 2 (which was only available in the POVRAY forum on CompuServe):

------------ Begin Forwarding --------

A Message from POV-Team Coordinator Chris Young

This beta test version of POV-Ray 3.1 is being distributed only via the CompuServe GO
POVRAY forum.  You may use it and share it with friends but do not re-post it on any
web site, newsgroup, online service, bbs, cd rom,  or any other form of public mass
distribution.

The POV-Team will only accept bug reports via public forum messages on GO POVRAY on
CompuServe.

This version fails to render any scene which used halo or atmosphere.  Keep a copy of
3.02 if you need these features.

The documentation is VERY INCOMPLETE.  The new interior{media{...}} feature which
replaced halo and atmosphere is totally undocumented except for the sample scenes. 
We're working as fast as we can.

This is an expiring beta with no source code.  We will not release any source code
until all platforms are in final release.

At this time only Mac and MS-Dos platforms are being released.  Others will follow as
our time and resources permit.

To everyone who complains about this very limited, incomplete release... all we can
say is we're doing our best and we figured a partial release was better than nothing.

------------ End Forwarding --------


>2.  I noticed the Windows version indicates that it is compiled with
>Watcom "Pentium II Optimized".  Since all Pentium II's have MMX
>instructions... does this mean it will make use of them when running ona
>P2 (or P-MMX)?
>
>I agree with other further back in this list that OpenGL and similar
>"3D" technologies don't help POV (although they do help modelling
>software).  However, despite all the media hype over the Multimedia
>benefits of MMX, MMX probably helps povray better than almost any
>application.  MMX instructions are SIMD math instrucions, allowing fast
>multiple operand mathematical operations (add, sub, div, mul, and
>logic).  Povray could probably see some big speedups by using MMX
>instructions deep down in the renderer in a few places for math
>calculations.

You should not trust Intel and its adds...MMX is SIMD (Single Instruction, Multiple
Data) and the MMX unit uses the FPU registers of the processor, BUT it only offers
integer calculations for 8,16 (and 32?) bit components of a 64 bit register. This
mechanism requires the no change to existing multi-tasking systems (because they save
the state of the FPU registers for each task) but is forces the compiler to switch
between FPU and MMX mode - this switching is (much!) slower than the benefits of MMX
could be for POV-Ray. Additionally, MMX is not implemeted very well in most compilers
- you will usually have to use assembler programming (and loose POV-Rays
cross-platform functions) to get a speed advantage over non MMX code.
But you are not totally wrong: Intel has "MMX-2" (not implmemented in existing
processors yet), which provides floating-point SIMD - but currently the make a big
secret out of it...
However and alliance of the other x86 makers (AMD, Cyrix and Centaur) has created
"3DNow!", which is build into AMDs current K6-II and Cyrix and Centaur will offer it
soon, too. This standard is supported by Microsoft, but currently there is no compiler
out there for it (as far as I know).
If you have not heard about 3DNow! you may want to refer to this article:
<http://www.heise.de/ct/english/98/12/028/> (This is an English translation of a
German computer magazine article! The translations are free and so they are a little
it (two issues) behind...)

>Going back to the "no unix version?" question.... will the 3.1 source
>for the Windows version be released?  (and again.. why not in beta...
>makes testing much easier when you can see the source)... I'd already
>know about the MMX question.. or be able to attempt it myself... if the
>source were around..

The source code won't be available until final 3.1. This has been the case for all
previous betas (at least for 3.0) as far as I know.


Thorsten

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