[x3d-public] touchsensor on USE Shape

[Andreas Plesch]

Prompted by x3dom issue https://github.com/x3dom/x3dom/issues/220 I am
trying to find out what the spec. says about this situation:

A TouchSensor is influenced by a Shape node which is a USE reference to a
DEF Shape. Here is an example:

https://gist.githubusercontent.com/andreasplesch/3fef1d65a72
891d2c4eb8e044d9b918a/raw/1f5d2544c10ea5e3a2b866248e00e34826
2dc4a1/TouchSensorOnUSE.x3d

Most x3d browsers sensibly produce Touch events only when the USE reference
to the node is indicated.

But since there is only one node which is referenced multiple times x3dom
cannot distinguish between these references and produces Touch events if
any of the references is indicated.

The spec. offers

http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/
components/pointingsensor.html#OverviewOfPointingDeviceSensors

"Pointing device sensors have influence over all geometry that is descended
from the sensor's parent groups."

This should be clear enough but since the DEF node appears as a USE
reference in the sibling position and x3dom literally uses the DEF node in
this position, it identifies the same node as being touched no matter which
of the references is actually indicated.

Common sense dictates that it is necessary to distinguish between the
multiples references to the same node. I think I convinced myself that the
spec. does not need clarification.

-Andreas

-- 
Andreas Plesch
Waltham, MA 02453
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