[osg-users] I created 10000 cylinder, osg run very slow

[Sebastian Messerschmidt]

Am 22.07.2015 um 14:12 schrieb Trajce Nikolov NICK:
> Hi Sebastian,
>
> few months ago I tested something (was the lighting system) 
> implementation with updates via osg::Image and osg::Texture - not 
> related to instancing at all, but the mentioned method. My colleague 
> then did benchmarking and the update of the Image (and the texture) by 
> OSG was terribly slow - the same thing using raw OpenGL calls 
> out-performed the one from OSG. I also remember Robert implemented 
> then the Vertex Attribute Divisor wrapper for OSG so it might really 
> need example of these with various techniques ...
Thats right for data dynamically changed via texture. Static data is 
incredibly fast however (I'm talking ~1mio trees @30Hz min) .
Getting slightly off-topic here, but:
Are you sure you had resizing and mipmapping disabled for the 
texture/image? That is certainly a performance killer.
>
> Thanks for the ping :-)
>
> Nick
>
> On Wed, Jul 22, 2015 at 1:59 PM, Sebastian Messerschmidt 
> <sebastian.messerschmidt at gmx.de 
> <mailto:sebastian.messerschmidt at gmx.de>> wrote:
>
>     Hi Nick,
>
>     The implementation is almost to complicated. Using instancing with
>     osg::Image and a texture almost beats all other implementations
>     I've tested so far in terms of complexity and performance.
>     Maybe we should some more examples for this to osg.
>     Cheers
>     Sebastian
>
>>     Hi Luo,
>>
>>     have a look at this paper - it is OSG related with GL calls (In
>>     the latest OSG release there are OSG wrappers for most of them).
>>     It will help you with large number of instancing and controlling
>>     each instance separately
>>
>>     http://3dcgtutorials.blogspot.com/2013/09/instancing-with-openscenegraph-part-ii.html
>>
>>     Hope it helps
>>     Nick
>>
>>     On Wed, Jul 22, 2015 at 9:25 AM, Sebastian Messerschmidt
>>     <sebastian.messerschmidt at gmx.de
>>     <mailto:sebastian.messerschmidt at gmx.de>> wrote:
>>
>>         Hi,
>>
>>             Hi,
>>
>>             I need to use cylinder to simulate the “ladder”.  So
>>             there are many cylinder to create. I new a osg::Geode ,
>>             and then use it to new 10000 osg::MatrixTransform, all
>>             these osg::MatrixTransform were added to one group.
>>
>>             But the program runs very very slow.
>>
>>         Are you testing in debug mode?
>>
>>             In fact I create the same scene using opengl, the program
>>             runs quickly.
>>
>>         Are you using the osg::Shapedrawable for the cylinder shape?
>>         Try to replace it with a simple triangle for testing to see
>>         if the geometry or the transforms are your bottleneck.
>>
>>         I'd use hw-instancing for this amount of copies of a simple
>>         geometry or bake the transformations into big geometries
>>         representing hundreds of cylinders each.
>>
>>         Also if the 10000 elements are spatially separable and thus
>>         not all of them in the view at the same time you should use
>>         some grouping to balance your scenegraph. Simply putting
>>         10000 transforms into one group most likely will kill
>>         performance, as all children will have to be traversed each
>>         frame.
>>
>>
>>
>>             How can I upgrade my program?
>>             thanks.
>>
>>         Can you provide a more detailed description or an example?
>>         Your question is too open to get you specific answers.
>>
>>
>>             Thank you!
>>
>>             Cheers,
>>             LUO
>>
>>             ------------------
>>             Read this topic online here:
>>             http://forum.openscenegraph.org/viewtopic.php?p=64386#64386
>>
>>
>>
>>
>>             Attachments:
>>             http://forum.openscenegraph.org//files/mfc_osg_124.cpp
>>
>>
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>>
>>
>>
>>     -- 
>>     trajce nikolov nick
>>
>>
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> trajce nikolov nick
>
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