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double O seven

OpenGL What do the graphics depend on?

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Sorry to be asking a question so basic, but the more I think about it the more my curiosity grows. I know that with a high quality game like ones that require DirectX 9 and the latest OpenGL. But is it multiple texture maps that requires a game to run on a high end video card? Or what makes a game so graphically advanced that it needs an expensive video card to be viewed at its highest quality? I really didn't think it was the poly count, because that is up to the processor right? Just curious.

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Guest Anonymous Poster
I'm guessing mostly a combination of serveral factors:
- particular features (OpenGL extension or DirectX version) that must be supported by the card (I think this is the more important one). A good example is shaders. These, sometimes very specific, features make it easier (or even possible) for developers to support a certain visual effect. Not many developers are willing to code that effect in software if it isn't available in the hardware. So you need a card that supports it to run the game.
- increased polycount
- more and higher resolution textures
- more calculations are being moved from the CPU to the GPU

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anti-aliasing is a big feature. being able to move that from the cpu to the gpu gives amazing speed ups to games.

but like AP said before "more calculations are being moved from the CPU to the GPU" is the main point.

DirectX and OpenGL have certain calls that a programmer makes. at the beginning of an application the API (that is what DirectX and OpenGL are to programmers) checks your cards capabilities. so when a programmer makes one of these calls to the API it knows wheather your card can do it, if not the API takes over and makes a "software call". software call = bad. hardware call = good. programmers have to balance the fact that not everyone is going to have the latest and greatest cards... meaning those people will have to make more software calls if the programmers puts too many high end calls to the API. one of the "tricks" to get around this is to let the user set some options about their video card (and some are found and calcualted automatically by the programmer) so instead of making a software call that would be slow, the program just skips the call altogether.

example: jane's card supports 4x anti-aliasing. dick's card supports 1x anti-aliasing. bob writes a program and tells the API he wants 4x anti-aliasing. the game runs great on jane's computer, and crappy on dick's. bob decides to help his friend dick out and writes an "option" to let dick set the graphics quality to 1x anti-aliasing. now when the API goes to make a call to the anti-aliasing it checks to see if the option is set... if so, it does the 1x anti-aliasing instead of 4x. and now the game runs nice on both dick and jane's machines.

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Quote:
Original post by cheez_keeper
anti-aliasing is a big feature.
Anti-aliasing is certainly something that has improved with newer cards, but I've not yet seen a game that requires it. If the hardware doesn't support it, it's simply turned off. It's not something supported in software, at least under Direct3D.

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Quote:
Original post by superpig
Quote:
Original post by cheez_keeper
anti-aliasing is a big feature.
Anti-aliasing is certainly something that has improved with newer cards, but I've not yet seen a game that requires it. If the hardware doesn't support it, it's simply turned off. It's not something supported in software, at least under Direct3D.


at least for me anti-aliasing is still too slow... just looking at Elder Scrolls: Oblivion: If I have to decide whether to have anti-aliasing on (even only 2x FSAA) and lose precious FPS or simply turn it off and get that little extra FPS, my choice is clear, at least in a very demanding game like that.
Not exactly related to the question, but I still wanted to mention it ;)

I guess, the AP has mentioned the most important things already, so I don´t have anything to say regarding the original question... too bad :)

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