I made a skp, rb, html set to test what I understand so far about transformations on a 3x4x5 metre group. If you want to try it out temporarily unzip the files to your plugin directory.
transformations.zip
Here is a clip of it showing a group rotating around each of the axes in turn:
[flash=425,344:32q3oq38]http://www.youtube.com/v/aXxkHu7gSv4[/flash:32q3oq38]
The rotations are made with:
tr = Geom::Transformation.rotation(Geom::Point3d.new(ent.bounds.center), rv, theDegrees), where rv is the axis,
and the angle_between values with:
(t.xaxis.angle_between X_AXIS).radians
same for y and z.
From this, I gather if the angle_between values returned are 0-180-180, the group has been turned by 180 deg on the X_AXIS; and if 0_90_90, the group could have been turned 90 or 270 (-90) degs on the X_AXIS; and the same for the angle_between values for the other axis rotations.
The second clip shows the application of different series of rotations:
[flash=425,344:32q3oq38]http://www.youtube.com/v/TFAnDrHXaIg[/flash:32q3oq38]
Screenshots of rotations providing angle_between values of 90-90-90 shows there is either something fundamental missing or perhaps that an entirely different method is appropriate.
angle_between 90 90 90.jpg
Any suggestions about this most welcome...
Chris