> From: Naveen Leekha <[EMAIL PROTECTED]>
>
> When I try to zoom-in very close to the object, it gets clipped by the
> front-clipping plane. If I try to setFrontClipDistance( ) to a small value
> say 0.0000001d ), it doesn't render the object properly ( some polygons are
> arbitrarily missing ). Any ideas why this happens? Or is there's some other
> way by which I can zoom very-very close to he object?
>
This is a known difficulty with using a perspective view and depth buffering.
If the ratio of the back plane distance over the front plane distance is too
large (>3000) then objects near the back of the depth range will loose their
depth buffering. This will result in all kinds of strange effects.
What is happening is that the perspective view creates a non-linear relation
between Virtual World Z and screen Z. The worse the back/front ratio, the more
non-linear the relation. As I recall (this is a bit fuzzy), for ratio of 3000,
the front 1% of the VWorld space uses 99% of the z-buffer. For high ratios,
objects which are not at the front of the scene will be rendered as if depth
buffering was turned off.
Using a frame buffer with more z resoulution (24 bits instead of 16 bits) will
help, but a back/front ratio of 100000 with objects in the back half of the z
range is going not look z-buffered no matter what you do.
Doug Gehringer
Sun Microsystems
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