Without vram, blitz uses a managed mode. Which I believe is a case of performing ops in system memory, then uploading to vram. And also keeping textures in sys ram until referenced by a model, to help cards with low vid mem(I.e texture swapping. Whether mark's code does this or dx I dunno)
But with vram flag, this managed mode is circumvented so that copyrects etc translate into(in gl terms, dx is not something I'm familar with) simple direct buffer copies from backbuffer to texture bufer (I.e no trip to system memory ala non v-ram flag mode, as color buffer/tex buffers are all agp side)
I could be wrong, but if I am then I'm just as confused as you are to what it means ;)
But with vram flag, this managed mode is circumvented so that copyrects etc translate into(in gl terms, dx is not something I'm familar with) simple direct buffer copies from backbuffer to texture bufer (I.e no trip to system memory ala non v-ram flag mode, as color buffer/tex buffers are all agp side)
I could be wrong, but if I am then I'm just as confused as you are to what it means ;)