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Tokage
06-12-2003, 07:43 PM
I'm using texture coordinate generation to apply a wood texture to the interior of a quadric cylinder, but there's always a little band of the same color about an eighth of a unit wide at 0 and 180 degrees, and I don't know how to get rid of it. I even know why it's there: I'm generating coordinates from the planes y=0 and z=0, and where y=0 intersects the cylinder (at 0 and 180 degress), lo and behold, there's a seam. What I need to know is how to get rid of it. Any suggestions?

peter.vullings
06-12-2003, 10:36 PM
I've seen this post before, haven't I http://www.opengl.org/discussion_boards/ubb/smile.gif
I don't know much about openGL yet, but I'll throw in some ideas incase it jogs something..

The seams aren't on the edge of a texture, are they? Perhaps the texture isnt being stretched to the edge of the poly (or its not set to wrap somehow)?

Ignore this post if its irrelevant, I'm up to the stage of spinning a cube in the center of the screen!

[This message has been edited by peter.vullings (edited 06-13-2003).]

Tokage
06-13-2003, 06:13 AM
No, I'm sure the problem is the one I mentioned above. I changed it to x=0 and z=0, and lo and behold, the seam moved accordingly.

mogumbo
06-13-2003, 09:46 AM
Hmmmm. I can't quite picture what you're describing. Any chance of posting a link to a screenshot? That might help....

Tokage
06-13-2003, 05:04 PM
Sure, here you go:
http://www.dotsomething.net/theprob.jpg

I marked in pink-o-vision for the world to see. This is really starting to annoy me :\

gator
06-13-2003, 07:00 PM
Obviously, your texture coordinates are wrapping around from 1 back to 0.
What to suggest, I don't know.

Tokage
06-13-2003, 07:54 PM
Exactly. I need to know how to fix this. Is there some way to map texture coordinates cylindrically? This doesn't seem like something they would just not include...

DFrey
06-14-2003, 01:38 PM
I can't really tell much from that screenshot, but my guess would be that you need to do change your texture coordinate generation. Perhaps scaling the texture matrix along the axis perpendicular to the seam will help too.

mogumbo
06-16-2003, 06:50 AM
Sorry, but there's no way to do cylindrical projection with automatic texture coordinate generation; you can only do planar projection or environment mapping. You'll need to compute the texture coordinates yourself. If you're computing the vertices for your geometry, just compute the texture coordinates at the same time.