Sorry, I realized after I sent the message that I ran some of my tests
improperly.  Here's the real results.

On Thu, 23 May 2002, Noah J. Ternullo wrote:

> On Tue, 21 May 2002, Daniel Selman wrote:
>
> > Noah,
> >
> > Lots of info! Some questions for you.
> >
> > 1. What is your front and back clip distance set to? How big are your maps?
>
> FrontClipping distance: 5000.0 meters
> BackClipping distance: (default for SimpleUniverse) 0.1 meters
> The maps used in the images is: 4200m x 2000m (Max Elev. is 200m)
>

This is correct...

> > 2. Have you updated you video driver?
>
> I believe I have the most up to date driver for my development
> hardware.  Additionally I've tried on multiple machines, one with ATI
> hardware (a laptop), another with a GeForce4.  The results are the
> same.  I've even tried using different version of Java3D.
>

This is correct.

> > 3. Why apply a TextureAttributes to the Map, when it is not transparent?
>
> I apply TransparencyAttributes to the Map (even when its not
> transparent) because I can't seem to get the MapOverlay to show up at all
> without doing so.  Both objects seem to require have a
> TransparencyAttribute Object in order for the MapOverlay to show
> up.  Perhaps this is a clue?
>

Still true

> > The fact that the MapOverlap is not rendered looks like a depth sorting
> > issue, which would possibly point to a depth buffer precision problem. Have
> > you experimented with varying the Z-offset or using a PolygonAttributes
> > offset?
>
> I have put the MapOverlay and the Map in an ordered group.
> Using the settings discussed in the previous e-mail, there appeared to be
> no change regardless of render order.
>

This isn't correct.  Here's the tests, and their results.


TransparencyAttributes Set to nicest in Map & Overlay
Ordered Group child order
0 Map
1 MapOverlay
Result:
        MapOverlay doesn't appear in ParellelProjection
        MapOverlay unusually displayed as lines in PerspectiveProjection
                Same as last case in e-mail

http://www.corelore.org/~noah/problempictures/ObliqueView-MapNoTA-OverlayDisplayed-PathDisplayed.jpg


Ordered Group child order
0 MapOverlay
1 Map
Result:
        In the overhead view, you can see the map overlay, but's you
        can't see through it.  Everything appears somewhat black.

http://www.corelore.org/~noah/problempictures/OverheadOrderMOM-TAonAll.jpg
        Perhaps this is because the overlay is being rendered first, and
there's nothing behind it but black background?  That's really a stretch,
but I couldn't figure it out.
        Removing the overlay, reveals a perfectly normal Map with none of
the issues described in the previous e-mail.  Another clue?



> I haven't player with the Z-offset using the PolygonAttributes yet.  I
> play with both of these things more and get back to you.
>

I tried playing with an the Z-offset (setPolygonOffsetFactor).  Here are
the tests and the results.

TransperencyAttributes set to nicest in Map & Overlay
RenderingAttributes Zbuffer of Overlay set to 10
Result:
        NO CHANGE FROM Default problem

TransperencyAttrributes set to nicest in Map & Overlay
Rendering Zbuffer of OVerlay set to -10
Result:
        No Change FROM Default problem

TransperencyAttributes set to nicest in Overlay only
Rendering Zbuffer of Overlay set to 10
Result:
        Same as in ObliqueView-MapNoTA-OverlayDisplayed-PathDisplayed.jpg


TransperencyAttributes set to nicest in Overlay only
Rendering Zbuffer of Overlay set to -10
Result:
        Same as in ObliqueView-MapNoTA-OverlayDisplayed-PathDisplayed.jpg


>
> > How about an OrderedGroup? Do you know that you cannot render
> > overlayed transparent objects with any certainty without using the
> > transparency depth sorting feature (1.3)?

Yes, and No.  I thought if I used an ordered group, I could overcome my
problem in 1.2.1.  Effectively, I want to overlay a transparent surface
over a non-transparent surface.  Both surfaces wind up being
IndexedTriangleArrays.  The lower surface is opaque (with opaque per
vertex alpha values, and no transparencyAttributes set.)  The upper
surface isn't opaque with per vertex alpha values set (Color4) and
TransparencyAttributes set.)  The upper surface completely covers the
lower surface.
  The problem I am seeing persists, even if the upper surface is
"removed" from the scene via a switch group ("ie. switching it off).  I'm
not sure where to go next.

> >
>
> I am unable to see either the Map or the MapOverlay in Java 1.3 by
> default.  I haven't looked into this further yet.
>

That's the other thing I mentioned.  I'm afraid to alter my code for 1.3's
benifit for fear of having nothing working at all.

> > 4. Have you tried this on other machines / video cards / OSes?
> >
>
> I haven't tried different OS's but I have tried different Machines, and
> different Video Cards, and different version of Java 1.2.1 including the
> _03 and _04 versions for both OpenGL and DirectX.
>
> > Sincerely,
> >
> > Daniel Selman
> >
> > Author - "Java 3D Programming"
> > http://www.manning.com/selman
> >
>
> Noah Ternullo
>

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