Hi Robert, hi all, As mentioned in some articles, Direct3D *seems* more popular among game developpers than OpenGL (contrary to "pro" apps). I don't know if it is true, but I'm inclined to belive so. This is a bit what I was saying a few months ago about OSG and the game industry. Well of course OSG's code isn't the only to use OpenGL, but maybe advertising (a bit) towards game industry would help reducing the devouring importance of D3D. Moreover, advertising towards game industry would help us for the OSG 3.0, since we would have more console-oriented developpers (Except XBox!).
I also wanted to say that, far beyond the MS goals of world domination, the competition between - at least - two major APIs is profitable. I disagree with the article roughly saying that OpenGL is dead and/or far behind D3D, but we at least can say that when one of the two is a bit behind the other, then all tend to reduce the gap. There are many cons to such a competition, but I guess we all can agree with this, can't we? IMHO, neither D3D nor OpenGL should die. And finally, about having OSG to support D3D... Well I'm not *that* happy with it because D3D non-portability is an offence to the C++; but I think that it should be done, and it should be done *after* or even *during* the refactoring for an API agnostic code. We should rely on incoming D3D devs to let this part be developped (the more they are interested in it, the more it would be developped/tested). However, I agree than the community *must* be kept coherent (even if it would be a bit harder), and that OSG should not switch to a D3D style code. And I guess simply adding an OpenGL->D3D mapper is a mistake because D3D conviced devs would see it as a trickery/fraudulent "fake D3D". Sukender PVLE - Lightweight cross-platform game engine - http://pvle.sourceforge.net/ Le Wed, 25 Feb 2009 11:36:06 +0100, Robert Osfield <[email protected]> a écrit: > I'm writing a second email on slightly different tack, as the one I've > just written covered the anti-trust/support for OpenGL aspect, this > one I'll do a what if tack that looks at practicalities. > > With looking at any new feature one has to weigh up the costs vs > benefits, considering Direct3D support is no different. > > A) Benefits of introducing DIrect3D. > > 1) Marketing value of providing support for API that some end users > see as important. > > 2) Access to better drivers where OpenGL drivers are poorly > featured or implemented. > > 3) Access to XBOX / XBOX 360 > > 4) Possible growth in community due to attracting those who are > convinced by the marketing on > Direct3D value. > > B) Costs of introducing Direct3D. > > 1) Core scene graph API must be converted to across to an API > agnositic interface, this would break > backwards compatibility. > > 2) Implementations of HAL API's (OpenGL/Direct3D/OpenGL ES etc) > would have to be decoupled from > scene graph. > > 3) Developer time in designing, implementation and debugging new > infrastructure. > > 4) Ongoing Developer time in maintenance and development once > infrastructure is implemented. > > 5) Division of labour - rather than everyone using and testing > OpenGL, the community gets split > over multiple profiles. If you labour gets split too much then > quality will go down, and forward > progress would falter. > > 6) Testing matrix goes up significantly as you now have multiple > paths to tests, so the testing load > goes up and the number of combinations of failures goes us. > Cost of doing releases would go > up and the risk of regressions not being spotted also goes up. > > 7) Risk of undermining support for OpenGL within software and > hardware vendors. > > 8) Risk of culture clash and increased community friction. > OpenGL/OpenGL ES centric developers > in general will be relatively platform agnostic and value > portability, Direct3D centric developers > will care about Windows and unlikely to be bothered by > regressions in portability or OpenGL support. > > > Now in the context of OpenGL/OpenGL3.0/OpenGL ES discussions about the > costs of B.1 to B.6 are something that we will have to consider, so > the cost of adding Direct3D into the mix is potentially lower, however > there is still a significant cost that can't be hidden by the other > work. There is no doubt that a larger active development community > and would be required, and managing this bring extra strain on the > project, keeping the community cohesive would be priority. Even a > couple of years of cash injection to fund this effort wouldn't elevate > the ongoing project costs of maintaining ports - one would have to > mark sure that a larger and still cohesive community is able to pick > up when specific dev funding peters out. > > At this point in time, I believe the cost vs benefits of supporting > OpenGL ES exceeds that of OpenGL 3.0, given that we'd be able port > existing OSG applications to new devices/platforms, and we'd pull in a > new breed of application developer into the community. OpenGL 3.0 > doesn't offer any new platforms, applications types or community, > rather it's just a continuation of how we refine the scene graph to > better handle modern hardware. These refinements are just as relevant > to OpenGL 2.0 as well, so I think port to OpenGL 3.0 is possibly a bit > mis-leading as a goal in itself, rather it would fall out of a goal to > refine the scene graph for hardware programability, and a goal to > support OpenGL + OpenGL ES + OpenGL 3.0. > > The strategy I feel we should take is to look at refactoring the core > API so that it is more HAL API agnostic, but retain the OpenGL/OSG > language conventions where possible, also at the same time look at > making the state management far more flexible and better suited for > handling shader only implementations. This work would then give us > the ability to do OpenGL 2.x, OpenGL 3.x, OpenGL ES and OpenCL. There > are costs involved in this, and dangers in running the community too > thin if we can't introduce enough new blood, and keep on board enough > of the existing community that are OSG-2.x based. > > Once we are in the position of having a re-factored core scene graph, > and with the infrastructure to do multiple rendering back-ends, the > costs of a introducing and maintaining a Direct3D profile will be > lower. Whether the benefits would outweigh the costs at this point is > still hard to say. The benefits aren't likely to go up over time, > rather with a faltering MS and it's competitors getting significantly > stronger time is likely to diminish the benefits of Direct3D support. > > A successful campaign in support of the OpenGL family, and better > support for OpenGL drivers would also diminish the value of Direct3D > support. If we got the technical issues with OpenGL dirvers sorted > out, and we got the value of OpenGL out to the application buyers then > pressure for such a port would be diminished. This isn't entirely > under our control. What is under our control is getting the message > our, and putting pressure on the hardware vendors that don't yet > support OpenGL well enough. > > If we achieve this then the only value proposition for a Direct3D port > would be XBox and XBox360 support. This takes us in the context of > more general console ports. Which ones do we target and which ones > first? Wiii? Playstation2/3? XBox/XBox360? New consoles in > development? > > Another take completely to take would be to look for, instigate, and > project that converts OpenGL calls to Direct3D ones. Such projects > have existed in the past, but none I know of are in wide use. One > could possible make things easier be selecting just portions of OpenGL > to expose, perhaps by us providing OpenGL profiles that make it easy > to do such an API mapping. Such a OpenGL subset -> Direct3D project > would be of wider value than just to the OSG community so one could > spread the costs of development and ongoing support. > > Robert. > _______________________________________________ > 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
