[osg-users] [Fwd: Mesa and gldirect]

Dorosky, Christopher G christopher.g.dorosky at lmco.com
Mon Mar 23 14:42:32 PDT 2009


In situations where your customer has bought hardware for another primary use (try tens of thousands of laptops), ATI or even Intel wins out over Nvidia on cost it seems.
Then we are stuck with integrated graphics, and poor drivers.

Where the developer has a choice of hardware, just saying no to ATI makes sense.
When your hardware is dictated, you have to do whatever you can.

I have never used Direct3D/DirectX and don't know a thing about it. Maybe we are on the losing end of this battle.

Chris 

-----Original Message-----
From: osg-users-bounces at lists.openscenegraph.org [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of Paul Martz
Sent: Monday, March 23, 2009 3:48 PM
To: 'OpenSceneGraph Users'
Subject: Re: [osg-users] [Fwd: Mesa and gldirect]

There's a very simple answer to the ATI problem: don't buy ATI. Seriously, their poor OpenGL support has been well-known for at least seven years, if not longer. In light of this knowledge, why do people keep buying ATI cards for OpenGL use? It just doesn't make any sense.

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 Jean-Sébastien Guay
Sent: Monday, March 23, 2009 2:04 PM
To: OpenSceneGraph Users
Subject: Re: [osg-users] [Fwd: Mesa and gldirect]

Hi Jan,

> Honestly, I think this will be counterproductive. It will only give 
> companies an excuse to neglect OpenGL support further or to drop it 
> completely ("You can use the emulation!"). The latter would be 
> disastrous for all non-Microsoft platforms.

Since the OpenGL over Direct3D layer will only work on Microsoft platforms for obvious reasons, I don't see how this will affect other platforms at all. If some developer wants to do 3D on Linux, they have to use OpenGL.

Basically, this is a follow-up to an earlier discussion (a rather long and heated one as I recall) saying that there were two ways to improve the OSG experience on Windows platforms or for ATI/AMD hardware, where OpenGL drivers are pretty bad compared to nVidia:

1. Demand better OpenGL support in drivers (which may be hard and does not depend on us, i.e. we can ask but we have no control over the result)

2. Create a technological solution, of which an OpenGL over Direct3D layer is one example.

Of course, it would be much preferable if vendors would, out of their own volition, improve OpenGL driver quality on Windows. However, since most games run on Direct3D, there is little incentive for them to do this. In most markets where OpenGL support is important, the software is already cross-platform, and thus moving to Linux is less of an issue. 
This means that the situation with OpenGL driver quality on Windows is likely to get worse as developers who depend on OpenGL move to other platforms and stop demanding good OpenGL driver quality.

> I fail to see the benefits of such move - why to run OpenGL on top of 
> Direct3D? Is there *any* usable hardware that has only D3D drivers and 
> does not support OpenGL?

Perhaps not, but for most hardware which has Direct3D support, the Direct3D driver quality is higher than the OpenGL driver quality on Windows (either in speed, number of serious/show-stopper bugs, etc.). 
There's a big difference between supporting OpenGL and supporting it *well*, and since there are no enforced conformance tests, vendors can support it only partly if they want...

Basically, I'm trying to find a way so that OpenGL apps can run well on Windows, independent of what vendor made the graphics card. Since there is a large pool of Direct3D applications on Windows, making OpenGL calls go through Direct3D before getting to the video card driver might be one way of doing that.

Of course, this is all theoretical, we can't know what the trade-offs are until we get a prototype running. And in any case, I'm just relaying info I got, seeing as this discussion was raised before. If the majority of people don't see the benefit, nothing will come of it and it'll just die, and we'll just go on as we have in the past.

J-S
--
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Jean-Sebastien Guay    jean-sebastien.guay at cm-labs.com
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