All,
[apologies for a long post]
I have come up against a very strange rendering problem using QuadArrays. I hope I've
just missed something, but I've beaten my head against this for a few hours now and
can't make head nor tail of it.
I have run into problems writing an example for my forthcoming book "Java 3D
Programming". The example uses SimpleUniverse and defines 3 Viewers. The first
(default) Viewer is a top down view of a space within which the other two Viewers can
move ("Dan" and "Jim"). The space is created by defining "walls" using ColorCubes
"tiled" around the edge of the space and a floor using tiled 2 x 2 QuadArrays. I.e. we
end up with a square space with walls that are 2 units high, and has a floor
positioned at -1.
Both the "Jim" and "Dan" Viewers have PlatformGeometry and a ViewerAvatar assigned so
that as they are moved around (using a KeyNavigator) they can see and identify each
other. The KeyNavigators modify one of the TransformGroups in the ViewingPlatforms
MultiTransformGroup in order to move the Viewers. The first view is therefore a
top-down view of the overall space, the second is "Dan's" view and the third is
"Jim's" view.
Again, everything *almost* works... tantalizingly so. The problem appears to be that
when either "Jim" or "Dan" do not have the center of the square space (0,0) within
their field of view *ALL* of the tiled QuadArrays that compose the floor of the space
disappear (in their view). They will reappear as soon as the Viewer is rotated again
such that the center of the space is again their view.
I initially thought it was a clipping problem and fiddled with the clipping planes,
but no luck. Then I though it was a Normal problem on the QuadArray, so I ran
everything through the NormalGenerator, again no luck.
Then it dawned on me that *only* the tiled QuadArrays disappear, not all the walls. So
I replaced the tiled QuadArrays with tiled ColorCubes for the floor also, and sure
enough the ColorCubes stay put, even when (0,0) is not in view.
Is there a rational explanation for this behavior?
I now have the example with the tiled QuadArrays (which are textured incidentally)
slightly above the tiled ColorCubes for the floor. As soon as the center of the space
is no longer in view (for a viewer) the textured tiles disappear to reveal the
(shocking pink!) underlying ColorCubes!
Any and all advice gratefully accepted. I really don't want *another* of my examples
to turn into a lesson in: "this is how you would do this if it weren't for this bug in
Java 3D"...
Incidentally, it occurred to me that this might be related to Bob Gray's problems of
last week (Transparency Problems (Still!)).
Sincerely,
Daniel Selman
[EMAIL PROTECTED]
http://www.tornadolabs.com
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