From: Dan Johnston (dan.johnston++at++nrc.ca)
Date: 08/01/2002 06:38:57
A few days ago someone on this group asked about turning the visibility
of objects
on/off based on how close you were to them. The response was to use
Level Of Detail
objects. I have another option, but I have lost both the origional
message and the
response.
We had a similar problem and we used the object's traversal. Our
problem was
to add geometry for navagation and assembly aid when two objects were
close to
each other, but not display this geometry when the object were beyond
our limits.
Each object (node) had a pfTraversor callback, and we used this to
extract the
3D centroid of each object. The application program did a 3D distance
calculation
and if any target object was 'close enough' to any of the trigger
objects, then a
pfSwitch was changed to turn on the display of the navagation geometry.
You could
actually see the trigger object swing back and forth over the target
objects and
watch the geometry switch on and off following the path of the trigger.
And, once
set, it is fully automatic and controlled by the callbacks and
application methods.
You could easily make a version of this with distance calculations from
you own
target objects and the viewpoint of the observer.
Hope this helps! (and is not too late).
Dan Johnston
--
___|__ |
/ | \ ||\ Daniel (Dan) Johnston
/___|___\ || \ Dan.Johnston++at++nrc.ca
_____|____ || \ National Research Council of Canada, London, ON
| | | || \ Integrated Manufacturing Technologies Institute
\___| | | ||____\ Tel: (519) 430-7081 Fax: (519) 430-7090
\_o_\___|____|_|______\_ Inst: http://www.nrc.ca/imti
\ o / These opinions are my own! Not those of NRC.
\________________/ Virtual Reality:
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