[Bf-committers] [Bf-blender-cvs] SVN commit: /data/svn/bf-blender [22941] branches/blender2.5/blender/config : * BGE optimisation tweaks.

[Mitchell Stokes]

On Wed, Sep 2, 2009 at 1:40 AM, <jmsoler at free.fr> wrote:
>
> You should be careful about fastmath :
> https://projects.blender.org/tracker/index.php?func=detail&aid=8861&group_id=9&atid=127
>

This is the BGE, not Blender itself. When it comes to a game engine,
precision isn't as import as speed. However, doing some benchmarking,
it seems that the two optimizations did little for frame rates. Here
are the results of the default cube scene:

Base line (BGE_CXXFLAGS = ['/O2', '/EHsc', '/GR'])
Min: 93.9956808054
Max: 1032.34567385
Average: 923.693778411

With "/fp:fast"
Min: 88.6841658558
Max: 1030.30926569
Average: 926.200376381

With "/arch:SSE2"
Min: 81.7896209204
Max: 1027.67823461
Average: 925.338981321

With "/fp:fast" and "/arch:SSE"
Min: 66.4432752384
Max: 1040.1976284
Average: 920.833553036

Operating System: Windows 7 RC
Graphics card: NVIDIA Geforce 8600m GT
Processor: Intel Core 2 Duo T8100 (2.1GHz)

As one can see, the differences are negligible. When testing I noticed
that the average framerate would vary about 5~10fps per run with the
same flags/settings.

I also did a quick test with the YoFrankie! svn to test some logic,
etc. I wasn't as exact when recording results from this, but just from
watching the framerate, it looked like there was little difference
between the baseline and then with fp:fast and arch:SSE.

I encourage people to do their own benchmarks and testing as well!

Cheers,
Mitchell Stokes (Moguri)