Forearm twist
I've been looking at forearm twist rigging lately. How complex does this need to be? How many joints do you need to have? At the moment I'm particularly working with figuring out the best way to do the skinning; the rigging control can come later, I just want to get a good method down for good deformation.
The most successful method I've seen is one that uses 4 twist joints along the length of the forearm; the weights are just about perfect by default and the twist is nice and smooth. But I notice that a lot of game characters only seem to have one twist joint. The HumanIK skeleton generator in Maya2012 also generates only one twist joint. So is that actually sufficient?
thanks for any tips!
The most successful method I've seen is one that uses 4 twist joints along the length of the forearm; the weights are just about perfect by default and the twist is nice and smooth. But I notice that a lot of game characters only seem to have one twist joint. The HumanIK skeleton generator in Maya2012 also generates only one twist joint. So is that actually sufficient?
thanks for any tips!
Replies
The way the engine handles the skinning also has a big influence on what is most appropriate. For example, some game engines now use "dual quaternion" style skinning which preserves volume very well while joints twist counter to each other. In that case you can most likely get away with only one twist joint even if it's going to be seen closely.
Another factor to take into account is the data/processing cost. For most engines the rotation data from the joints needs to be baked (so you get one key per frame) which means having 4 additional joints per arm can ultimately mean a significant increase in the amount of memory the animations end up taking up.
Even with DQ, you still need twist bones.