Sign in to follow this  
Dirge

Bones vs. Tags

Recommended Posts

I'm putting some prelimary thought into an animation system I plan to implement and I'm wondering what direction people around here have gone as far as using either bones or tags. (To me a bone (or joint) is just a transformation matrix like in any standard animation system that vertices can index to and a tag is _very_ similar, however isn't exported along with a model but is defined externally through a text file). For example, lets say I want to attach a single thruster effect to a point on a space ship model. I have two choices; add the bone to the model and re-export it, or I could just add the tag as a child of the model root and attach to that. It seems like it would be annoying to always have to ask an artist to re-export if I'm tweaking the thruster position, but then again, perhaps the only time I'd be doing this is if the model changed anyways (so maybe it was better off in an artists hands). Has anyone run into these practicality issues or is it just not a big deal. The reason I ask is I'd hate to have to waste time supporting both if just using bones is sufficient. Thanks for any insight.

Share this post


Link to post
Share on other sites
A better idea is to allow a tag to specify a joint name as its base position and orientation, rather than fixing it to the root.

'Course this can bloat your animation data (since a joint name/reference lookup needs to be included).

Share this post


Link to post
Share on other sites
I'd include the tags in the models format and have the bone structure and whatnot be a separate format that the mesh references.

A tag is basically an artist selected offset, the best solution when you want a mesh to have an 'attached mesh' but don't want to hardcode the location where the meshes are 'attached'. In skeletally animated meshes, the tag has an added bonus of referencing more than one bone, for an added plus to the attachment system :)

With enough foresight and planning, your animation system can do whatever it is you want it to do.

Share this post


Link to post
Share on other sites
Winterdyne: I was just giving an example in the case of the ship. Normally tags would be able to attach to any bone, not just the root model/world.

Wudan: Yes, interesting point. Originally I hadn't really considered the possibility of seperating the model and skeleton but perhaps that might make things much easier. In that situation I suppose it wouldn't be a far stretch to have a tag file as well since what I'm really striving for is a streamlined production pipeline where I'm not waiting a few hours for an artist to move a bone 0.002 units over, wasting his and my time in the process.

I gave it some thought though and it seems something like a tag is somewhat redundant if you're able to easily change your bones, so I might just concentrate my efforts more on that.

Thanks guys.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this