Inquisitive minds want to know ! And if they don't -- well like that ever has stopped me before ..
I'm thinking that in the last step the reset of frame and skin should probably be done outside of the interpolation #ifdef. It seems like a valid precaution just in case the frame and skin for the baseline are invalid for the new model, and the QC doesn't send updates for either or both of them. This is something that could possibly happen even in stock ID software Quake.
Also, all of the code here is also good for GLQuake and is a more sensible way of doing it than in the old interpolation tutorial. This would include the clearing of the interpolation data on a model change (I've seen GLQuake crash - very occasionally - with the old code on account of not having that step). You don't need to pollute R_RotateForEntity and you don't need special case handling for the viewmodel this way. It's just cleaner.
