Setting rotation axis

Engines, Libraries and Tools Xith3D Forums
#1

Hi

When I apply rotations to the body parts of my .ASE model - they all appear to rotate around
a point located below the feet of my model. - how can I stop this?

Cheers

Rmdire

#2

You don’t have to double post.

If you don’t get an answer that normally means, that nobody has one.

I don’t have any experience with rotating parts of ASE models, but I’ll try anyways:

rotX, rotY, rotZ create a rotation matrix, that rotates around (0,0,0) and it discards all translation data.

If you want to apply a rotation to a TransformGroup and want to keep your translation data, you can do:

transform.setRotation(Matrix3f);

Or you could first simply print the translation data ( transform.get(Vector3f) ), so you can see, if the pivot point data is stored there.
If it is not, there are two possibilities:

  1. There are parent-Nodes containing that information (pretty unprobable, because then you actually couldn’t have done things wrong)
  2. The ASE-loader doesn’t support pivot-points or it is a bug.
    If this is the case, it would be a good idea for you to look into the ASE-loader code, to check if it is supported…

Arne

PS: If you have general problems with the javax.vecmath API I’d suggest to look into the Java3D Javadocs.

#3

Hi Thanks for answering
and please for give my double post.

yep I tried what you said - i did

                     tempTrans.get(v);

for each body part and they contained (0,0,0)

so then I check the parent for each - and low and behold the parents contained the pivot points

I am a total novice so I am unsure what I need to do next
do I remove each of these parents?

Cheers

Rmdire

#4

strange …

As far as i understood you the structure of the ASE-Object is build like this:

TransformGroup (contains translation to pivot point)
|
your child Node, you’re changing

so if you set a rotation in the child node it should rotate around the childs (0|0|0), so around the parents pivot-translation.

#5

arrgh double post.

I’ve replied to your other post. Often I find a good way to solve problems is to go back to something that works (i.e. the demo), validate it works, then try with your customisations.

Will.

#6

yes arne , thats what I would have thought,

but the Child always rotates around a point somwhere below the models feet, which is the center of origin for the whole model

#7

Then you’ll probably change the wrong TransformGroup. You should not change the TransformGroup, that contains the pivot point translation…

#8

Got it

Thanks arne and William

the parent node had another parent (Uber Parent) - eeeee gaaaad sakes*

when I rotated UperParent - it worked

Thanks for all your help

#9

Ah, good one arne, I forgot how confusing that could be to new users.

There is a reason why I have two transforms and not one per node in the TGTree - it’s so you can rotate it easily without having to reapply the translation. I believe there is a flag that can tweak this behaviour. For new users it’s definitally worth studying the diagrams in my tutorial.

Will.