128x128 would also be faster to draw since the stride across video ram as you stepfrom pixel to pixelis smaller, improving cache coherency.Īs the user changes zoom, you might check for a given texture what the screen resolution of a texel is (divide size on screen by texture size). Todisplay those you dont need 512x512 textures (128x128 would be ok without losing detail onscreen). It occurs to me that if you are displaying, say, 10x10 textures on a 1280x1024 screen, then each tile is only 128x102. The numbers in my math are made up but you could substitute your own values. Also theres probably shaders and other bits & bobs using up the remaining memory. You should also consider that there is probably some driver overhead in GPU ram, as well as any render targets you have, and vertex / index buffers which I assume you use for rendering. Thats great news about the extra memory from mipmaps. Why would there be such a hard limit? Is there some way to change what this apparent "hard limit" is set to? So why would I get an 'out of memory' error? I would expect opengl to simply use more of my available system ram. And I can tell for sure that OpenGL is using system ram for the textures because I can see the "free" ram going down in 'top'. The odd thing is this: this architecture doesn't have dedicated video ram, it's shared. This, along with simple measurements while looking at "top", indicate to me that I'm hitting up against an ~128MB limit for textures. When I get to about 118-120 of these, I get an "out of memory" error from OpenGL, and I also get this message on the console: "error: INTEL_ESCAPE_ALLOC_REGION failed". Here's the problem: I have code that allocates a bunch of 512x512x32 textures (about 1MB apiece). Oh, you should also know that i have 1 GB of available system memory. I'm running with the Tungsten Graphics "Gallium" driver on Ubuntu 9.10 Karmic Koala. (It's my understanding that the GMA500 is a PowerVR under the hood, but I'm not sure). I am working on an embedded OpenGL graphics application running on an Intel Atom z530 with the GMA500 graphics hardware.
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