Sorry. I didn't notice some of the larger problems. Now that you mention
the distances you used, I think the problem is related to Z-buffer
resolution. OpenGL uses an integer Z-buffer and coordinate depths are
converted to integer values for writing into the Z-buffer. The farther
apart the geometry, the less resolution your Z-buffer has. The side effects
of using too large a space are much like what you are seeing: seaming
triangles, missing surfaces, cracked edges.
I believe the Java3D spec probably has guidelines for geometry size with
respect to the Z-buffer. I know OpenGL does but I don't have my reference
book here with me to provide it to you.
Roberto Speranza
President, Dot Internet Solutions Inc.
mailto:[EMAIL PROTECTED]
http://www.dotinc.net/
----- Original Message -----
From: Patrick van Bergen <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: November 4, 1999 12:55 PM
Subject: Re: [JAVA3D] Strange waves in my cubes
> They problem here may be a that some triangles are culled. But it is
> different. For one thing, I didn't use triangles to build these cubes; I
> used quads. Also, the problem affects the entire cube, not only the edges.
>
> Somehow the effect is much smaller when the distance between the viewer
and
> the cube is smaller. I am using distances to several thousands of units
> (meters).
>
> When I add 2D text shapes in front of these cubes, it also looks very
messy,
> some parts being visible, others not.
>
> Patrick
>
> ----- Original Message -----
> From: Matthew Warren <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: donderdag, november 04, 1999 3:12
> Subject: Re: [JAVA3D] Strange waves in my cubes
>
>
> > I have seen a similar effect when displaying rows of sphere primitives
> that
> > overlap, I wasnt sure why and didnt consider it a problem - I assumed it
> was
> > to do with the number of triangles making the spheres. IE: triangles
that
> > partially covered each other when spheres overlapped where removed
rather
> > than clipped to the right shape?
> >
> > I assume from reading below this is the culling problem?
> >
> > Is it possible to get J3D to clip intersecting tringles when shape3D's
> > intersect so they render with 'flush' edges rather than just removing
the
> > triangle?
> >
> > Matthew.
> >
> >
> > >This appears to be a culling problem. The only triangles that are
> > >disappearing are those at the edges of your rounded cubes. My best
guess
> > >is
> > >that the rounded edges of the cubes are not tesselated enough i.e. not
> > >enough triangles were used to define the rounded sections. Because
there
> > >aren't enough triangles, some of the triangles have normals that are
not
> > >quite correct and they are being culled. As you rotate the view,
> naturally
> > >different triangles would be affected. To fix the problem, you need to
> > >create the cubes with more triangles in the rounded regions.
Hopefully,
> > >your code can be adjusted to do that.
> > >
> > >Roberto Speranza
> > >President, Dot Internet Solutions Inc.
> > >mailto:[EMAIL PROTECTED]
> > >http://www.dotinc.net/
> > >----- Original Message -----
> > >From: Patrick van Bergen <[EMAIL PROTECTED]>
> > >To: <[EMAIL PROTECTED]>
> > >Sent: November 4, 1999 7:21 AM
> > >Subject: [JAVA3D] Strange waves in my cubes
> > >
> > >
> > > > Hai there,
> > > >
> > > > I am building an application that contains a number of rounded
cubes.
> > >When
> > > > these cubes overlap eachother I get these strange 'waving' effects,
> that
> > >can
> > > > best be explained by looking at the attached picture. I say waving
> > >because
> > > > triangular waves go through the sides of the cube when I zoom in and
> out
> > >of
> > > > the objects.
> > > >
> > > > I tried changing some of the renderingattributes of the appearance
> > >without
> > > > much effect.
> > > >
> > > > Has anyone seen such an effect before? I am not doing anything
special
> > >here.
> > > >
> > >
> >
>
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