[x3d-public] X3D Agenda 19 June 2020: Mantis issues

[Don Brutzman]

Thanks Michalis, very helpful.  Have added this to Mantis 1310.

* Mantis 1310: near, far clipping planes indirectly specified by NavigationInfo, consider addition to X3DViewpointNode
   https://www.web3d.org/member-only/mantis/view.php?id=1310

So far so good, however: practice has shown an important use case that is difficult to handle: shifting between local views and faraway (e.g. terrain-oriented) views.

... so we might consider the ability to override these values in a Viewpoint, since they are typically needed when shifting between such views.

Suggested specification addition:

23.3.1 X3DViewpointNode
https://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/navigation.html#X3DViewpointNode

Viewpoint : X3DViewpointNode {
  SFFloat    [in,out] nearClippingPlane -1     -1 or [0,infinity)
  SFFloat    [in,out]  farClippingPlane -1     -1 or [0,infinity)
}

"If specified and non-negative, the values specified for nearClippingPlane and farClippingPlane define the near and far clipping plane distances when the X3DViewpointNode is bound.  Otherwise these values are defined by the bound NavigationInfo node, including when the X3DViewpointNode is unbound."

Hopefully this strikes a good balance... X3D3 defaults are maintained, and X3D4 authors have more straightforward options.


On 6/19/2020 1:21 PM, Michalis Kamburelis wrote:
> NavigationInfo supports specifying them:
> 
> - NavigationInfo.visibilityLimit is the far clipping plane, if non-zero.
> 
> - NavigationInfo.avatarSize[0] / 2.0 is the near clipping plane, if browser follows the spec recommendation: """It is recommended that the near clipping plane be set to one-half of the collision radius as specified in the avatarSize field"""
> 
> See https://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/navigation.html#NavigationInfo .
> 
> Castle Game Engine honors it (with some exceptions, e.g. using shadow volumes forces the far clipping plane to infinity).

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