[osg-users] Fwd: Slow down with shared nodes

Andre Normann andre.normann at gmail.com
Wed Mar 8 01:39:08 PST 2017

Hi Robert,

I used 3.2.3 to load the obj files and converted it into ive format. In
3.2.3 I load the ive file, build my scenegraph and I get 60 fps. When I now
load the same ive file into 3.4.0, build my scenegraph, I get the slow

- There must be something which is causing the slow down in OpenSceneGraph
- The obj loader is creating a lot of primitive sets, which is not optimal.
In near future I will try to fix that issue.

I created a test file. Simply do an "osgviewer SlowDownTest.zip".

2017-03-08 9:45 GMT+01:00 Robert Osfield <robert.osfield at gmail.com>:

> Hi Andre,
> On 8 March 2017 at 08:40, Andre Normann <andre.normann at gmail.com> wrote:
> > hopefully I am getting closer. I find out, that the source model might be
> > the problem. I exported an obj file from Bentley Microstation and
> imported
> > into OpenSceneGraph. When I now export the scene into an osg file, I see
> a
> > lot of PrimiteSets (e.g. > 1000). So I will end up with a lot calls to
> > DrawElementsUShort. When I load the obj file into 3dsmax convert it into
> a
> > fbx file and reexport it from OpenSceneGraph into an osg file, I have
> only
> > one PrimitiveSet with one DrawArrays call. This file is working well in
> > 3.4.0 with sharing nodes.
> >
> > So I guess there might be a problem with sharing osg::Geometry which has
> a
> > lot of primitive sets. In 3.2.3 it was working well. What do you think?
> It sounds like data import path is the crucial part, perhaps changes
> to the .obj plugin between 3.2.3 and 3.4.0 are what is causing the
> difference.
> Doing an:
>     osgconv myfile.obj myfile.osgt
> In 3.2.3 and 3.4.0 will tell you the differences that the plugin and
> any optimization passes are making.
> Is there any chance you could share an example of one of these .obj
> files that is causing the performance problems?
> Robert.
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