Mingtian Ni wrote:
Hi all,
For those geometries which are compact, DistanceLOD works
fine. But it doesn't work well for elongated objects.
Has anyone implemented a LOD class based on the distance between
the eyepoint and the bound (especially Box bound) of an object?
The way we do it in Xj3D is to build our own LOD system. To start with,
you need some behaviour that is going to trigger each frame. In this
behaviour, you then do a pick using a point. The point represents your
avatar in virtual space. For your structure that you want to control as
LOD you then build something like this:
Group
+---------+----------+
Switch Group
/|\ +------+------+
Geometry Big Med Small
for BBox BBox bbox
each range
Under the switch is the geometry that you use for each of the ranges.
The switch controls what is visible. Turn picking off on this branch. On
the other branch is a collection of geometry that represents the various
range bounds. Make sure the appearance sets them to invisible. Next,
make use of the UserData to give you some information to refer back to
the appropriate piece of geometry that that box refers to - you're
obviously going to have more than one LODed object in the scene and the
picking just gives you the picked item, not the structure it refers to.
Your point pick returns you a collection of these boxes and you can tell
based on the box ID which object and which range you are at, and then
set the switch appropriately to show the correct range.
--
Justin Couch http://www.vlc.com.au/~justin/
Java Architect & Bit Twiddler http://www.yumetech.com/
Author, Java 3D FAQ Maintainer http://www.j3d.org/
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