   DrawIndexprimitive performance minIndex, NumVertices
  Just wondering what people's performance experiences have been with providing accurate minIndex and NumVertices arguments to the DrawIndexedPrimitive function.I can calculate these for my model class, no big deal.  Just curious.I'll run my own test eventually, but I'm assuming I'll need a larger data-set than I have to really see the difference.   
  I have to admit that I've never tried to profile it... but my understanding is that correct usage of those parameters can yield better pre/post TnL cache hits on the hardware, as well as requiring the GPU to traverse less (potentially unused) vertex data.Jack   ;  Software T&L processes all the vertices first, then passes them on to hardware, so any extra vertices specified in the range will definately cause some kind of performance hit.nVidia HW T&L processes the vertices on the fly based on the indices read, and completely ignores these two values.  The values shouldn't affect performance at all.ATI HW T&L... I'm not sure what it does.  It requires accurate values to render correctly.  Whether it transforms everything first or does it on the fly, I'm not sure.Also, be aware that specifying the wrong values might mean the required data isn't uploaded to the card when needed.  It could also mean transferring too much data to the card if you specify too large a range.  So there is a chance of a combination of extra transform time, and extra data transfer time.Profiling your system isn't going to be indicative of all past, current and future hardware and driver combinations.  Considering how easy it is to specify correct values, you might as well do it to guard yourself against a system that incurs a big hit.   