[x3d-public] visibilityRange for X3DFogObject: specification erratum detected

[Andreas Plesch]

Hi Don,

Thanks.

> Andreas, if you have suggested prose for “explain that fogVisibility corresponds to the visibilityRange field” then please send that.  We can at least create a Mantis issue for eventual resolution.

The table 17.5 at

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

mentions 'fogVisibility' but the term is not clearly defined.

The bullet list above the table has

- fogInterpolant is the fog interpolant, see Table 17.5 for calculation.
- fogDistance is the distance from point on geometry to viewer's
position, in coordinate system of current fog node.
- fogColor is the currently bound fog's color.

Let me suggest expanding that list with an additional line:

- fogVisibility (Table 17.5) is the currently bound fog's
visibilityRange, in the same coordinate system as fogDistance.

Michalis may have background on introducing the 'fogVisibility' term.
Perhaps it is an attempt to decouple from the fog node to allow
flexible use of world or local coordinate systems for computations.

Best, Andreas