Could someone tell me approximately what is the max number of textures I can load into memory before the performance totally break?
Thanks!
It depends on many things. Like the size of the texture, the size and number of components, whether you MIP map, the available video memory and depending on the implementation the size of your framebuffer and use of display lists etc. Then there are other factors like the size of your AGP aperture and through that available system memory.
Basically there’s no easy answer to your question.
In fact when you ship some program/demo/game to end user he must have options to decrease datail of textures (this includes for example switching trilinear/mipmapped textures to bilinear, also scaling original textures to 1/2, 1/4 … size)
Your best bet is to test it yourself. On Quadro II and Geforce2 boards we limited our texture sizes to 1kx1k with filling the 64Mb, and the performance is twice that of 2kx2k textures also filling the same 64MB. The same software gained 50% increase in speed on Quadro DCC, also filling the 64Mb, however, we were able to run texture sizes up to 2kx2k to reduce seams rather than tile with almost no loss in speed. Geforce4 technology increased the speed yet again, though only on the larger texture sizes, smaller textures seem to run the same speed as geforce3 for our application. Your application may utilize different sizes than ours, different distributions on area of models, etc. There are lots of variables.
Good Luck!