combine modes and textures

To enable a texture unit, one needs to bind a valid texture even if the combine modes do not access it … I have seen people creating fake 1x1 textures to do just that.

Assuming I have already a valid texture (say 256x256) bound to a texture unit (say 0) and I want to enable the other one just to use combine modes for calculations , does it make a difference in terms of performance if I bind a fake 1x1 texture to the other unit or simply bind the existing 256x256 texture again … ?


It shouldn’t make a difference as that texture won’t actually be used by the hardware.