[osg-users] OpenGL 3.1 at GDC

Paul Martz pmartz at skew-matrix.com
Mon Mar 30 11:59:26 PDT 2009


If the tool starts to act sluggish when rendering complex models, then
moving away from glBegin/glEnd to buffer objects would improve performance.
It would be unfortunate if someone were to use a poorly-written OpenGL or
OSG application and blame the poor performance on OpenGL and mistakenly
think that things would be better if the app had been written in D3D.
Uneducated programmers can code poorly performing apps using either API.

SketchUp really excels at very simple models on the order of a few hundred
triangles or less, so I suspect the performance bottleneck they have
designed into their application is probably not an issue for 99% of its
target audience and usage cases. Nonetheless, there's no excuse why the app
wasn't coded to at least use vertex arrays from the start, as they've been
commonly available since the early days of consumer 3D hardware, '96-'97.

As an aside, I understand @ Last Software (now the Google SketchUp division)
was started by a former AutoCAD employee.

(A note about performance tuning... I recall tinkering with the terrain
rendering code at my former employer, which used glBegin/glEnd to render the
terrain triangles. As a test to see how much of a performance hit this might
be causing, I commented out the rendering code altogether, recompiled, and
benchmarked it. I only saw about a 10% improvement. Obviously the
application's bottlenecks were elsewhere, and spending time converting this
to use buffer objects wouldn't help. Perhaps Google has done the same
analysis with SketchUp and came to the same conclusion.)

Paul Martz
Skew Matrix Software LLC
http://www.skew-matrix.com
+1 303 859 9466

-----Original Message-----
From: osg-users-bounces at lists.openscenegraph.org
[mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of R Fritz
Sent: Sunday, March 29, 2009 11:03 PM
To: OpenSceneGraph Users
Subject: Re: [osg-users] OpenGL 3.1 at GDC

> I guess I'm not too surprised. There seems to be an overall lack of 
> expertise in 3D graphics. Lots of people practice it without adequate 
> training or education. Ever look at a GL capture of SketchUp? It's 
> utter crap, glBegin/glEnd all the way.

Would fixing the OpenGL problems of SketchUp improve its performance as a
modeling tool?  That's its great strength, after all.  How would you make it
work, if you were designing it?

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