[x3d-public] LOD first level_changed event

Andreas Plesch andreasplesch at gmail.com
Fri Apr 6 17:11:52 PDT 2018

LOD has an outputOnly level_changed field which indicates the level
index of a child when it is activated.

Should the level_changed event be generated the very first time the
LOD activates any of its children ?

It looks like it should and the spec. does not treat the
initialization as a special case: When L(d) is activated for display,
the LOD node generates a level_changed event with value i where the
value of i identifies which value of L was activated for display.

On the other hand, the first display may not be considered a change
from a previous display. But it is a change from no display, and
generally logic using the event should work for the initial case as

So I think the answer is yes but thought it is worth raising the
question before the field is added to x3dom.

Perhaps it is time to put together a simple test using an existing LOD
example by adding a route from level_changed to a switch node to see
if it gets an initial value.

Any feedback welcome,


Andreas Plesch
Waltham, MA 02453

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