[x3d-public] Viewpoint centerOfRotation global or local

[Andreas Plesch]

Hi Don,

as suggested, there is a need to test browsers in that regard.

https://gist.github.com/andreasplesch/b96f20ccf0b6dd7af0cfb69f4a66e0fc
has a simple scene with a transformed Viewpoint, as provided by a
member of the x3dom-user mailing list. The center of rotation (COR)
should also be transformed, and be centered on the green sphere.

Here are the results for some browsers using
https://gist.githubusercontent.com/andreasplesch/b96f20ccf0b6dd7af0cfb69f4a66e0fc/raw/f8d03849300390dc814db52a506732eb00b4baf6/ViewpointCOR.x3d

All browsers transform the position of the viewpoint correctly.

x3dom: https://gist.githack.com/andreasplesch/b96f20ccf0b6dd7af0cfb69f4a66e0fc/raw/f8d03849300390dc814db52a506732eb00b4baf6/Viewpoint.html
 rotates around red sphere, eg. COR is not transformed

view3dscene:
 puts the center of rotation somewhere in between the red and green
sphere, probably at the center of the total scene.

freeWrl:
 center of rotation at green sphere, correct

Octaga:
 center of rotation at green sphere, correct

InstantPlayer:
 center of rotation at green sphere, correct

So there is a majority which follows your analysis. I agree that this
is the most expected and least surprising behaviour.

Best regards,

-Andreas

On Sun, Dec 6, 2020 at 10:59 AM Don Brutzman <brutzman at nps.edu> wrote:
>
> To maintain momentum towards ballot, have added the following (flagged as editorsNote for continuing review/improvement if needed).
>
> On 12/5/2020 9:16 PM, Don Brutzman wrote:
> > Simplest specification revision is to add a sentence to 23.3.1 X3DViewpointNode stating,
> >
> >      "The /centerOfRotation/ field is in the same local coordinate system as the current viewpoint node's /position/ and /orientation/ fields, in accordance with _4.3.5 Transformation hierarchy_.
>
> * X3D4 Navigation component, 23.3.1 X3DViewpointNode
>    https://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/navigation.html#X3DViewpointNode
>
> Cosmetic: am expecting that Dick and I will also sort the field descriptions in this clause, alphabetically by name.
>
> Also checked Mantis and found you had reported this issue in 2015 and it never got resolved (ouch).  Have flagged it as X3D4, updated, ready for final review.
>
> * Mantis 811, 23.3.1 X3DViewpointNode - Clarification of centerOfRotation
>    https://www.web3d.org/member-only/mantis/view.php?id=811
>
> Noted related issue which can also be reviewed for completion:
>
> * Mantis 1194, 23.4.4 NavigationInfo VIEWALL (or X3DViewpointNode viewAll) should be a required navigation behaviour
>    https://www.web3d.org/member-only/mantis/view.php?id=1194
>
> Thanks, keep 'em coming!  8)
>
> all the best, Don
> --
> Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
> Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
> X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman



-- 
Andreas Plesch
Waltham, MA 02453