By definition, if it is supported by more than one platform, it is cross-platform. Just like Kylix was meant to be cross-platform, even though it only supported Windows and Linux.

Sushil wrote:
”OpenGL is a hardware and a software spec”

Then:
”since it is tied directly to the underlying hardware it essentially becomes a hardware spec”

Eh? The whole point, Susheel, is that OpenGL is an open spec, and hardware has to support OpenGL, not vice-versa. So no, OpenGL isnt tied to a specific hardware. Infact, GLSL has had features which hardware had to catchup to later. Also, any platform/os/hardware can implement OpenGL. DirectX on the other hand, is a ‘closed’ spec, so no, you cannot write a virtual machine/hardware/operating system that implements DirectX without the explicit blessings of Microsoft.

sushil wrote:
”Can you implement OpenGL 3.0 on Intel on-board graphics cards”

Intel on-board chips have always supported OpenGL. Which particular version they support is irrelevant, because various chips will support various versions depending on market and price. The fact that they all can implement OpenGL makes it cross-platform.

Sushil wrote:
”Yes OpenGL ES is a subset of OpenGL…It’s however doesn’t mean that the OpenGL ES under both platforms is essentially the same.

Then the question arises, If OpenGL is cross platform then why does anyone need OpenGL ES?”

You asked a question when you answered it already yourself. OpenGL is cross-platform, precisely ‘because’ we have a version of it that can run on other devices. OpenGL ES is a subset, i.e, stripped down version of the desktop version to make it compatible with lower end hardware.

When you say OpenGL ES is not OpenGL its basically akin to saying Java ME is not Java because it isn’t Java SE (the ‘original’). Ofcourse its Java…just like OpenGL ES is OpenGL…

And if u see new hardwares yes…OGL 3.0 GFX hardwares are out!! Intel GMA dont support the opengl programmable pipeline. It still supports the Fixed functionality of OGL(if not wrong, till spec 1.5).

This is as simple if u compare a DX 10 hardware with DX 9 Hardware.

@Susheel wrote:
”As I said earlier, the same Linux distro can have different versions of OpenGL depending on different hardware. What does that tell you?”

That means if the hardware supports the extensions then….ur OS will enable the functionality.
The reason behind is that same extensions are being used by NVIDIA and ATI
Both have different hardware architectures and so different ways to implement!!

At the end, Nothing is completely cross platform…

In my above argument when I said “they are OSes and not platforms” I meant it in the context of this argument and OpenGL implementation and not a textbook definition of “a platform”. It is true that Nvidia has great drivers, but that doesn’t necessarily mean that having great Nvidia drivers = full cross platform. As I said earlier, the same Linux distro can have different versions of OpenGL depending on different hardware. What does that tell you?

My above argument makes the Mac argument moot. If you have the hardware, then nothing prevents you from having GL3.0 over there!

Yes OpenGL ES is a subset of OpenGL and in that it allows h/w manufacturers to make changes. It is not OpenGL standard since you can customise it to fit it to your hardware and that is exactly why PS3 and iPod have adopted it. It’s however doesn’t mean that the OpenGL ES under both platforms is essentially the same. They may have common origin and superficially look the same, but from there on things can diverge significantly as is the case with PSGL, like for instance PSGL doesn’t even support GLSL it supports CG which is essentially HLSL with a different name.

Then the question arises, If OpenGL is cross platform then why does anyone need OpenGL ES?

All valid points, and I was just going to leave it at that, right until you began talking about platforms…

(1) Linux /FreeBSD are different OSes, they cannot run DirectX, and ‘thereby’ they are different platforms. Duh! A platform isn’t just hardware. It can be a software-framework that allows software to run.

(2) The Mac is a platform (both hardware and software), and OpenGL is written all over it. SnowLeopard (yes, the developers version is up and running) has even introduced OpenCL.

(3) OpenGL ES isnt OpenGL? Get real. OpenGL ES is a ’subset’ of OpenGL, so yes, it ‘IS’ by definition OpenGL.

Sources

http://www.webopedia.com/TERM/P/platform.html
http://pcworld.about.com/od/softwareservices/OpenGL-3-2-Released.htm
http://www.khronos.org/opengles/

Did you guys even read what I said. I bet you saw directx and started to flame?
Chill out guys.

I used the words “DirectX10 class” GPUs to stress upon the type of hardware. Most of the things that were included in the 3.2 spec were already available as extensions under Nvidia drivers for like 6 months or more now. As far as ATI goes, they haven’t even released 3.1 drivers as yet.

… And to put a stress on what poster called “yes” said, I added that OpenGL 3.2 supports mostly all of DirectX10 level functionality and is not lacking in anyway.

The gist of my comment for those who have difficulty understanding, let me repeat, “same functionality was available under OpenGL for a long time now. The only difference was, the functions were available as extensions.” So it isn’t a big deal to move them up to spec level for Nvidia.

@Abhishek Dey
OpenGL performance lags behind Direct3D! You have any proof of that?
OpenGL and Direct3D are “APIs” ie they are interfaces to hardware and have equivalent performance for given hardware if the drivers are implemented properly. That said have you tried running a platform like Ogre3D using both APIs? You will be surprised by the results!
https://www.ogre3d.org/forums/viewtopic.php?f=2&t=44183&start=0
(scroll down and look at Sinbad’s comment).

Can you tell me how many “platforms” have full OpenGL 3.0 support as yet? No don’t give me names your favourite Linux, FreeBSD distro, they are OSes and not platforms. Platforms like iPhone and PS3s (PSGL2) have long since moved to OpenGL ES (which is not OpenGL).

And as Julien said….OpenGL is cross-platform.

Let Microsoft Dare to release a cross platform library!! Can it…??
dude..u r dealing wit a Cross platform advanced high performance graphics API….and OpenGL wil proudlyl Flaunt it …. always!!

ITS THE BEST CROSS PLATFORM API !!

Abhishek Dey says:
August 3, 2009 at 8:13 pm

OMG…NVIDIA Just Released officially der OpenGL 3.2 and GLSL 1.50 Drivers for Window/Linux.

To download NVIDIA Drivers:

http://developer.nvidia.com/object/opengl_3_driver.html

NVIDIA – LIGHTNING FAST!!!

…. Because everything was available via some extension or the other loooong before GL3.2. At the heart of it DX10 class GPUs support the exact same functionality (for more than 2 years now) under DirectX 10, and OpenGL is nothing but an interface to that. Nvidia had already released most of the extensions a year to 6 months ago. It’s trivial to move those things to spec level. Big deal!

@yes
When compared to DX10, nothing is lacking in OpenGL3.2. The major feature missing is well, a complete rewrite of GL.

What are your top three features that you perceive to be lacking in GL 3.2 ?

To download NVIDIA Drivers:

http://developer.nvidia.com/object/opengl_3_driver.html

NVIDIA – LIGHTNING FAST!!!

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