Hi,
i got a little problem with a texture that i want to map to a VRML object.
I want to do some sphere mapping on the VRML object.
The texture coordinates a generated automatically by OpenGL through
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP)
glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP)

When i draw a glutSolidTeapot everything works fine.
But when i draw a VRML object nothing is done.
So are the normals of the VRML object loaded?
Or is there any glDisable(GL_TEXTURE_2D) in this process? I couldnt find any
in the library that would cause this problem.

Another Problem is that the teapot that is drawn, doesnt look the right way.
The bottom of the teapot is drawn over the side faces. I mention that this
comes because of the projection matrix, cause there are some values which
normally are negative, but are positive and vice versa.
I think this comes because the y coords under Windows are flipped? But i
dont know if  i am right in that.

I would be very thankful if anyone could help me with the 2 Problems ;)

Fabian



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Fabian,

If you are drawing the VRML through the openVRML libraries then I
imagine that setting a texture would have no effect.  When the VRML
render functions are called, they load the texture/material that is
described in the VRML file itself.

You will need to add the texture in the VRML, either by hand or through
a modelling program like 3D Studio Max.

Which Teapot is drawn inside out?  If it's the glutSolidTeapot then I
have no idea, but if it is a VRML model that you've loaded it could just
be a problem exporting from the package that you used (it seems the
normals are flipped).  Try loading the model in a browser and see if it
looks the same.

To the ARToolkit community: If anything mentioned above is wrong then
please correct me.

Matthew


-----Original Message-----
From: owner-artoolkit@h ..................
[mailto:owner-artoolkit@h ..................] On Behalf Of Fabian Scheer
Sent: 03 February 2005 00:28
To: artoolkit@h ..................
Subject: texture problem with VRML objects

Hi,
i got a little problem with a texture that i want to map to a VRML
object.
I want to do some sphere mapping on the VRML object.
The texture coordinates a generated automatically by OpenGL through
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP)
glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP)

When i draw a glutSolidTeapot everything works fine.
But when i draw a VRML object nothing is done.
So are the normals of the VRML object loaded?
Or is there any glDisable(GL_TEXTURE_2D) in this process? I couldnt find
any
in the library that would cause this problem.

Another Problem is that the teapot that is drawn, doesnt look the right
way.
The bottom of the teapot is drawn over the side faces. I mention that
this
comes because of the projection matrix, cause there are some values
which
normally are negative, but are positive and vice versa.
I think this comes because the y coords under Windows are flipped? But i
dont know if  i am right in that.

I would be very thankful if anyone could help me with the 2 Problems ;)

Fabian



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Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.4 - Release Date: 01.02.2005

> > Another Problem is that the teapot that is drawn, doesnt look the
> > right way.
> > The bottom of the teapot is drawn over the side faces. I mention that
> > this
> > comes because of the projection matrix, cause there are some values
> > which
> > normally are negative, but are positive and vice versa.
> > I think this comes because the y coords under Windows are flipped? But i
> > dont know if  i am right in that.

On Thu, 2005-02-03 at 09:52 +0000, Leach, Matthew wrote:
> Which Teapot is drawn inside out?  If it's the glutSolidTeapot then I
> have no idea, but if it is a VRML model that you've loaded it could just
> be a problem exporting from the package that you used (it seems the
> normals are flipped).  Try loading the model in a browser and see if it
> looks the same.

Try using either of these:
glFrontFace(GL_CW);
glFrontFace(GL_CCW);

This sets what opengl considers to be the front and backside of the
polygon (determined by the clockwise, or counter-clockwise drawing order
of the vertices).
GL_CCW is the default value, so you'll probably need to set GL_CW when
you render the reversed object and reset GL_CCW when you're done with
it.

-Peter