[Visualpython-users] From newbie: major performance woes

[Jiang Q. <jq...@ph...>]

Hi:
	Sorry about the confusing subject line of my last email. I did 
manage to compile the beta, I just have major performance problem.
	I took a look at the code of sphere.cpp, and notice there's 
discussion about levels of details. I wonder, however, are all that 
exposed to the user? Is there anyway I can reduce the level of details 
from my script? Or if that's not possible, is it possible to in fact 
change the code manually and recompile?
	Another issue that may or may not have anything to do with my 
performance woes. There are several demos in the example directory does 
not run properly in my installation. Drape shows only a rod. Double 
pendulum is way slower than in 3.4, Hanoi shows artifacts whenever I 
move a ring. I'm beginning to think there might be something wrong with 
my beta installation. How can I check?
	Thanks in advance for your help.
								Jiang

On Wed, Nov 07, 2007 at 01:35:57AM -0500, Jiang Qian wrote:
> Hi all:
> 	I'm new to this list. I installed the stable visual-3.2.9 and it 
> worked great. But I really would like to to get the transparency to 
> work.  So I installed visual 4.beta16. I jumped through all sorts of 
> hoops, and finally got it to work. The transparency works quite well. 
> But I have serious performance issue.
> 	I mainly use visual to visualize packed spheres, and small 
> particles inside the spaces between them. In visual 3.2.9, a system with 
> a few hundred spheres packed inside a cube works very smoothly: I can 
> rotate, zoom at will with middle and right button. By combining the two, 
> I can essentially "walk" into the sphere packs.(The spheres rendered are 
> not perfectly smooth, but I manually changed some lines in the source 
> code to make the smoothness ok). It all works fine, the only thing I 
> miss is transparency.
> 	However, in visual 4.beta16, using identical code(with *no* 
> transparency yet), I get a spectacularly smooth and well lit spheres, 
> but the tradeoff seem to be heavy performance penalty: I can barely zoom 
> and move, the rotation is slow. Interactive zooming and rotation is the 
> key reason why I use visual: otherwise I can just render things in 
> povray. Needless to say, I would like to find a way to trade away some 
> of the more spectacular visual effects to have better interactive 
> performance.
> 	I tried to look through the documentation of beta, but there 
> aren't too much info about performance tuning. The only thing I found is 
> to set shininess to 0, which helps marginally at best.
> 	What other tricks can I use to improve interactive performance?  
> For example, can I tune the smoothness of the spheres? Sometimes my cpu 
> usage is not even fully 100%, but dragging, rotating and zooming the 
> image is still very slow.
> 	It'll really be a shame if I have to revert to the old version 
> due to performance issue.  There must be a way to balance performance 
> and effects.
> 	In a related issue. I also need to render particles between the 
> spheres in the pack. In the old version, I basically render them as 
> smaller spheres. But in the new version, there's a mention of point 
> objects, which seems to be just for that purpose. However, there's not 
> too much documentation of the point objects. How do I use them? Do they 
> offer a lighter overhead than the render spheres? Can I give them 
> colors?
> 	On the final note, a word about my system: I have a thinkpad 
> T43, with Pentium M Dothan 1.86MHz, 1GB PC2-4200 memory, ATI X300 mobile 
> discrete graphics(M22) with 64MB of VRAM, and 60GB 7200rpm disk. It's 
> not a powerful machine by today's standard, but it runs the old version 
> of visual just fine. Also, runs other 3D accelerated openGL programs 
> like googleearth and stellarium just fine(glxgears score, which I know 
> is not a benchmark, is around 1750 FPS).
> 	The software environment is an outdated ubuntu(5.04), with 
> custom compiled 2.6.18 kernel, gcc version 3.3.5, python 2.4, fglrx 
> proprietary driver 8.42.3(latest).  Numpy 1.0.3, the latest gtkglxtmm I 
> compiled and installed from source.  If you want to know more, let me 
> know what more relevant info I can give.
> 	If there's a simple patch for the stable version 3.2.9 that 
> enables transparency, I'll be very happy to use that, too. Because 
> really the stable version satisfies all my need except for 
> transparencies.
> 	Thank you all for any hint/help you can give.
> 								Jiang
> 
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