Sorry. I didn't think I needed to explain this, I mistakenly thought everyone knew it. Take your example of a DX3 app running on a DX10 implementation. The DX3 app gets nothing other than the DX3 API. Should the software developer attempt to use just one new feature in DX10, the only route forward is to port the _entire_ app to the new DX10 API.
Compare this to OpenGL. An OpenGL 1.0 app running on an OpenGL 2.1 implementation has access to all the features that have been added in each successive release, and you can modify the app to access those features without porting your entire app. Only in OpenGL 3.1 does this model change, but now you have a couple choices as an app developer: * Don't modify context creation. You continue to get a 2.1 context, but you also have access to many new 3.x features available as ARB extensions. * Create a 3.0 context, or a 3.1 context with the compatibility extension. You get essentially the same results as with 2.1, except the same new features you had access to as ARB extensions are now core features, and there are additional new ARB features available. You'll eventually port away from 1.x/2.x, but this system allows you to do so on your timetable, not someone else's. That is the compatibility difference between the two APIs in a nutshell. Paul Martz Skew Matrix Software LLC http://www.skew-matrix.com +1 303 859 9466 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tueller, Shayne R Civ USAF AFMC 519 SMXS/MXDEC Sent: Wednesday, March 25, 2009 9:09 AM To: OpenSceneGraph Users Subject: Re: [osg-users] OpenGL 3.1 at GDC Paul, In what way has D3D screwed the existing user base with each new release? I'm not trying to argue your point, I just want to understand where you're coming from here. -Shayne -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Paul Martz Sent: Wednesday, March 25, 2009 8:31 AM To: 'OpenSceneGraph Users' Subject: Re: [osg-users] OpenGL 3.1 at GDC > YES!!!!!!!!!!!! :))))))))))))))) > > but robert, thanks for your arguments! i will use them there. ;) > > best regards to all and other arguments are welcome too! I agree with Robert's sentiment. In many ways, D3D has chosen the easy way out -- supporting only one platform, and screwing the existing user base with each new release. This is the easy way to develop an API. Running cross platform, continuing to evolve and remain relevant, and not screwing existing users is a much harder task, but OpenGL has a proven track record of success in all these areas. _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
