Sign in to follow this  
locker_locker

Problem with poses and hierachies

Recommended Posts

Hello everyone, I'm writing because I have a very old problem regarding 3D transforms with hierarchies and animation (forward kinematics). Right now I am trying to get only the rotation part fixed (quaternions). I am exporting models from 3ds max using the standard ASE export plugin. All my transforms work correctly with or without animation fed to my own keyframer as long as there are not hierarchies. After some talking with a friend who knows more about this than I do, it turns out I was doing some things wrong. The main issue was that I was not decomposing the affine matrix exported in the ASE files, and was using the other exported data for the nodes, such as vectors and rotation axes. Now I am using the decomp_affine() function, just like in the ASE export plugin's source. It seems to decompose correctly. The problem is: when I have even the simplest bone chain, eg: three bones for an arm, forearm and hand, and I animate all three parts of the chain, the first child rotates badly. I think the axis has been affected by the parent's own rotation, so when the forearm rotates with its own keyframed animation, it always turns out wrong. I'm really not sure of this, though. I am not sure if I should be premultiplying by some matrix just before the edge loop, don't know if I should be multiplying the current matrix by the inverse of the parent (??), etc. Also, I get a quaternion when I decompose the matrix, what should I do with it? My friend told me that the quaternions decomposed from the affine matrix are in local space, as we saw it in the ASE exporter's source. Any help is much appreciated. I have had this bug for years and I need some serious help from the experts. Thanks a lot, Locker

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