What is texture memory, allocated with OpenGL, limited by?

Question

I'm making a 2D game with OpenGL. Something I'm concerned with is texture memory consumption. 2D games use a few orders of magnitude more texture memory than 3D games, most of that coming from animation frames and backgrounds.

Obviously there's a limit to how much texture memory a program can allocate, but what determines that limit? Does the limit come from available general memory to the program, or is it limited by how much video memory is available on the GPU? Can it use swap space at all? What happens when video memory is exhausted?

datenwolf · Accepted Answer · 2014-08-03 00:07:44Z

5

OpenGL's memory model is very abstract. Up to version including 2.1 there were two kinds of memory fast "server" memory and slow "client" memory. But there are no limits that could be queried in any way. When a OpenGL implementation runs out of "server" (=GPU) memory it may start swapping or just report "out of memory" errors.

OpenGL-3 did away (mostly, OpenGL-4 finished that job) with the two different kinds of memory. There's just "memory" and the limits are quite arbitrary and depend on the OpenGL implementation (= GPU + driver) the program is running on. All OpenGL implementations are perfectly capable of swapping out textures not used in a while. So the only situation where you would run into a out of memory situation would be the attempt to create a very large texture. The more recent GPUs are in fact capable of swapping in and out parts of textures on a as-needed base. Things will get slow, but keep working.

Obviously there's a limit to how much texture memory a program can allocate, but what determines that limit?

The details of the OpenGL implementation of the system and depending on that the amount of memory installed in that system.

edited Aug 3, 2014 at 0:07

answered Aug 2, 2014 at 23:22

datenwolf

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Prabindh Over a year ago

In addition, I would say it also depends on how the texturing itself is handled by the framework, like the case of "MegaTextures"/ Virtual texturing.

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