hi
when i render hair,there is v attribute,if i choose hair generation as ‘use sop geometry’ there is motion blur.but if i switch to ‘generate geometry in mantra’ the motion blur is disappear.

is there anything i missed or it's a bug?

thankyou!

v blur doesn't work for hengine procedural afaik. Deformation blur does, however.

what a bad news,use deformation blur will take double time and more memory to generate the hair geometry!

It shouldn't take double the memory, because the samples are computed sequentially, and sop memory should be unloaded between cooks. It will only take double the memory used to store the hair geometry.

A factor of 2 change is pretty insignificant in terms of cpu time. At least it doesn't take 1000 times longer.