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What is Happening with OpenGL?
Trapped In Windows Hell asks: "I was just at the local game store looking for a new game, and I noticed the absolute lack of ANYTHING other than DirectX games. Where has OpenGL gone, and what does this mean for games on GNU/Linux? If DirectX is so hard to program in, so clunky to use, and limits the game to being sold on only one OS, WHY do so many programmers use it? It seems logical (to me, at least) that programming as portably as possible, as simply as possible, and using standards where possible, leaves a lot more sales options open for the future... and DirectX seems to close all options *but one*." OpenGL use in Windows gaming has decreased dramatically in favor of the use of DirectX which is improving with each release. Will OpenGL continue to mature on the Windows platform (which arguably is the platform that drives most of the mainstream demand for graphics) or will it continue to stagnate as game and driver developers concentrate on the offerings from Microsoft?
When you only have 1 OS that you plan to sell your game on, why do you need something that is cross-platform? When 92% of home users run Windows, and many people who have linux also have a windows install for playing games, why would you put your extrememly limited money and time and effort into supporting something that's not needed? It's just like OS/2's problem. If they didn't support Windows applications, nobody would use their OS (even though it kicked ass), but if they did support it, nobody would natively develop for their OS because they didn't have to.
And from what I've heard, DirectX is not clunky nor is it hard to program in.
I think that once linux starts getting a much larger hold on the desktop, then we will start to see games being developed for more than one platform.
That just made me think, is there such a thing as an OpenGL for gaming consoles? Imagine how much nicer it would be if you could program your game once for one API, and run it on PS2, N64, GC, etc, etc. That would be really kickass!
If God gave us curiosity
Nowadays it seems that more and more new games are scheduled for release on the mac and pc simultaneously (or more often: the mac version released shorty after the pc version) Since most pc games are using DirectX, it's apparently not too hard to port them to OpenGL.
Come to think of it, the companies that are porting games to Mac OS are probably the ones that would be best at making linux ports. By porting the games to SDL they suddenly have a port that runs on two platforms.
Somewhere in the heavens... they are waiting.
I've done extensive OpenGl (Mesa) programming, and no it isn't. My programs ran equally well on a UltraSparc running Redhat and also regular PII machines with RH 6.2, without me even knowing any of the graphics cards that were installed.
OpenGL is a 3d programming API, which means it allows the programmer to not be concerned with the hardware itself, only that OpenGL is present so it can be called.
By the way, OpenGL is not really "open" software, it is a very expensive license from sun if you want to use it. Most Opensource developers would be interested in Mesagl, which is basically an open source version with some changes.
The upcoming Detonator 4's (supposed to be released last week, now "very soon") will support OpenGL 1.3. A good sign, as they are the major player right now. This includes:
Cube map texturing -- for higher quality environment mapping and lighting support
Multisampling -- for order-independent anti-aliased rendering of points, lines and polygons
New texture modes that provide more powerful ways of applying textures to rendered objects:
Texture Add Environment mode
Texture Combine Environment mode
Texture Dot3 Environment mode
Texture Border Filtering mode
Compressed texture framework -- to allow higher quality textures in less memory regardless of file format
That's not correct. Alice uses DirectX only for setting the screen resolution. The rest is all OpenGL. Trust me - we have it working just fine in Wine.
-Gav
--
Gavriel State, CEO
TransGaming Technologies Inc.
gav@transgaming.com
I'm still developing everything with OpenGL, and I'm still targeting mac and linux as well as windows, but I want to rationally address some points in the API debate:
D3D is clunky, etc
Not really true anymore. MS made large strides with each release, and DX8 can't be called a lousy API anymore. One can argue various points, but they are minor points. Anti-Microsoft forces have a bad habit of focusing on early problems, and not tracking the improvements that have been made in current versions. My rant of five years ago doesn't apply to the world of today.
I do think that the world would be a slightly better place if Microsoft had pulled an embrace-and-extend on OpenGL instead of developing a brand new API that had to be rewritten a half dozen times, but its water under the bridge now.
Open for more sales, etc
It has been pretty clearly demonstrated that the mac market is barely viable and the linux market is not viable for game developers to pursue. Linux ports will be done out of good will, not profit motives. From an economic standpoint, a developer is not making a bad call if they ignore the existence of all platforms but windows.
DX8 Gives more features
Some people have an odd view that an API gives you features. Assuming you don't care about software emulation, hardware gives you features, and an API exposes them. If you try to use vertex programs or bump env map on a TNT, DX8 doesn't magically make it work. DX8's hardware independence is also looking a bit silly now as they make point releases to support ATI's new hardware. They might as well say D3D-GF3 or D3D-R200 instead of DX8 and DX8.1.
All of Nvidia's new features have showed up as OpenGL extensions before they show up as new D3D features.
Divergent extensions haven't been a problem up until very recently. All of the vendors tended to support all the extensions they could, and if they had unique functionality, like register combiners, they made their own extension. The current status of vertex programs does piss me off, though. I really wish ATI would have just adopted Nvidia's extension, even if it meant not exposing every last bit of their hardware.
Abstraction in a high performance environment can be dangerous. If you insist that all hardware behave the same, you prevent vendors from making significant improvements. If the spec for behavior comes from people that aren't hardware oriented, it can be a huge burden. D3D still suffers somewhat due to this, with some semantics and odd features that make hardware guys wince.
The Good News
We are rapidly approaching a real golden age for graphics programming. Currently, cards and API's are a complex mess of hundreds of states and function calls, but the next two years will see the addition of the final primitive functionality needed to allow arbitrarily complex operations with graceful performance degradation.
At that point, a higher level graphics API will finally make good sense. There is debate over exactly what it is going to look like, but the model will be like C. Just like any CPU can compile any C program (with various levels of efficiency), any graphics card past this point will be able to run any shader. Some hardware vendors are a bit concerned about this, because bullet point features that you have that the other guy doesn't are a major marketing feature, but the direction is a technical inevitability. They will just have to compete on price and performance. Oh, darn.
It's a Turing machine point. Even if OpenGL 2.0 and DX10 don't adopt the same shader description language, they will be functionally equivalent, and could be automatically translated.
There is lots of other goop like texture specification and context management that will still be different between API, but the core day-to-day work of a graphics programmer will be basically above the disputes.
John Carmack