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OpenGL Opengl and graphics cards

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I don't know much about the basics of how opengl works, ie how it interacts with the hardware ... but here are some questions I was asking myself: 1. Most people on this forum who have tested my code or anything have quality cards like GeForces and the like ... but lots of people I know use the Intel 810 graphics driver (poor souls). How will GL programs do in hardware like that? 2. Similar to the previous question, as we say move back in time in the development of graphics hardware ... in what ways will the performance of the application be affected except for just frame rate? 3. If you remember, old games such as NFSIII had a "Software render" option. What is that all about? 4. Some GL extensions, as far as I know, are vendor specific, aren't they? How do I know which extensions will work where? Related: What are the GL_ARB extensions? Do they have any hardware dependence, or will just having the latest runtime do? Sure I will compile with the latest headers, but what about the runtime? 5. How does DirectX compare with OpenGL on the above counts of compatibility? Thanks in advance for taking time out to answer!

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Quote:
Original post by deavik
I don't know much about the basics of how opengl works, ie how it interacts with the hardware ... but here are some questions I was asking myself:

1. Most people on this forum who have tested my code or anything have quality cards like GeForces and the like ... but lots of people I know use the Intel 810 graphics driver (poor souls). How will GL programs do in hardware like that?

2. Similar to the previous question, as we say move back in time in the development of graphics hardware ... in what ways will the performance of the application be affected except for just frame rate?

3. If you remember, old games such as NFSIII had a "Software render" option. What is that all about?

4. Some GL extensions, as far as I know, are vendor specific, aren't they? How do I know which extensions will work where? Related: What are the GL_ARB extensions? Do they have any hardware dependence, or will just having the latest runtime do? Sure I will compile with the latest headers, but what about the runtime?

5. How does DirectX compare with OpenGL on the above counts of compatibility?

Thanks in advance for taking time out to answer!



1. never heard of it, so i wouldn't have the highest of hopes

2. unless you make your program frame rate dependant( game physics, etc ) or if the gl commands to update screen( i use SDL, so my SDL_GL_SwapBuffers() ) blocks until drawing completes

3. software renderer - use the processor instead of a graphics card. slow
http://www.mesa3d.org/ i think this does software...

4. dont use them yet

5. directx is windows only , thats the only compatability issue i need.

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Quote:
Original post by deavik
I don't know much about the basics of how opengl works, ie how it interacts with the hardware ... but here are some questions I was asking myself:

1. Most people on this forum who have tested my code or anything have quality cards like GeForces and the like ... but lots of people I know use the Intel 810 graphics driver (poor souls). How will GL programs do in hardware like that?

Depends on the quality of the driver and the hardware. In general the i810 aren't bad if you're just pushing a few textured polys, but they're missing lots of features.

Quote:
2. Similar to the previous question, as we say move back in time in the development of graphics hardware ... in what ways will the performance of the application be affected except for just frame rate?

Older cards won't have as many features. If you're using basic GL 1.1 then you're fine. If you start using extentions you need to check if these are available first (typically you'll be using at least multitexturing, which is an extension).

Quote:
3. If you remember, old games such as NFSIII had a "Software render" option. What is that all about?

What it says on the tin. Ignores the graphics card and does everything on the CPU.

Quote:
4. Some GL extensions, as far as I know, are vendor specific, aren't they? How do I know which extensions will work where? Related: What are the GL_ARB extensions? Do they have any hardware dependence, or will just having the latest runtime do? Sure I will compile with the latest headers, but what about the runtime?

ARB extensions are vendor-independant and usually availible on lots of hardware. Ideally stick with these whenever possible. You can use glGetString(GL_EXTENSIONS) so your code can determine at run time what extensions are available and which aren't. Theres a whole section on extensions in the forum FAQ.

Quote:
5. How does DirectX compare with OpenGL on the above counts of compatibility?

Depends on the drivers, but usually about the same.

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Thanks for the replies! glGetString(GL_EXTENSIONS) seems to be the best way to do things for now. And I read in a wiki article that on Vista they would clamp to a Opengl 1.4 version support. I don't need to worry, though, till date I haven't used a single extension except for GL_BGR_EXT!

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