> If the vrml author fails to specify
> screenHeight, then take the default value as being equal to
> whatever the current focalDistance value is. (Or better yet,
> equal to 0.6180339887 of the current focal distance ...)
Having default values that aren't one particular value makes me very
nervous. I can't think of a good reason why, except that it seems like
the kind of feature that is easy to add but might turn out to have
annoying implications when it is time to implement.
Once VRML gets animation and field-to-field connections, we'll be able
to do things like:
DEF myCamera PerspectiveCamera {
focalDistance = ... some animation expression ...
}
....
Cube {
width = USE myCamera.screenHeight
}
And an implementation will have to figure out how to make the cube's
width change because the camera's focalDistance is changing, when
there's no direct connection between the two. Certainly possible,
just... annoying.