Re: Proposal: Replace LevelOfDetail with a faster LOD node

Brygg Ullmer ([email protected])
Fri, 21 Apr 1995 20:56:20 -0800


At 1:19 PM 4/21/95, Gavin Bell wrote:
>I propose that this description replace the existing LevelOfDetail
>specification in the current VRML spec:
>...

With this definition, LOD should also be functional for switching sound
sources, no? It might even work as a simple proximity-activation mechanism
until the behaviors issue begins to be fleshed out... all http- or
file-spec'ed URL sound file pointers might by default be considered
one-shot sources, so an LOD node might be set up to point at an empty node
(or null sound) outside of a (say) 3 meter radius, and inside of the radius
some real URL-spec'ed sound (or live source) might be specified as an
effectively proximity-triggered source. Do you see any problem with this
node multipurposing, Gavin? (It was much more difficult to say what
"square pixel area" meant for sound files.)

Also, I suspect some of the discussions on acoustic properties for sounds
reflecting off various materials are loosely comparable to ray-traced
reflections and refractions from the visible geometries employed in our
spaces (and I'm not familiar with much out there in the way of real-time
raytracing). It's useful to consider, but probably isn't critical in the
realization of first-generation acoustic spaces.

--Brygg

>...
>The specified center point of the LOD is transformed by the current
>transformation into world space, and the distance from the transformed center
>to the world-space eye point is calculated. If the distance is less than the
>first value in the ranges array, then the first child of the LOD group is
>drawn. If between the first and second values in the ranges array, the second
>child is drawn, etc.
>...