[x3d-public] visibilityRange for X3DFogObject

[Andreas Plesch]

https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-IS.proof/Part01/components/environmentalEffects.html#X3DFogObject

lists limits for the visibilityRange as 0 to minus infinity, for the
abstract node.

https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-IS.proof/Part01/components/environmentalEffects.html#Fog

list limits for the visibilityRange as 0 to plus infinity, for the
concrete node.

https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-IS.proof/Part01/components/lighting.html#t-foginterpolant

assumes a positive visibilityRange (and probably should explain that
fogVisibility corresponds to the visibilityRange field).

So I think the abstract node also should list 0 to plus infinity as
limits (unless there are historical reasons).

This is not critical for implementations since Fog is the only
concrete node inheriting from X3DFogNode but should be addressed.

Apologies if this is already addressed in the very latest versions.

-Andreas

-- 
Andreas Plesch
Waltham, MA 02453