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View Full Version : Cylindrical Texture Mapping Problem in v.9



phuile
10-29-2006, 02:12 AM
I've been getting an annoying problem when wrapping an image around a cylinder in v.9. The wrap generates extra squashed copies of the entire image before the image repeats. If you wrap once around the cylinder you get 1 squashed copy; wrap twice and there will be two squashed copies on diagonally opposite polygons; and so on.

Can anyone else recreate this behaviour? Is it really a bug? It's darned annoying and took me by surprise to find this in such a critical area as texture mapping. I don't recall seeing this problem in previous versions.

Thanks for any feedback or confirmations.

Petre.

Sensei
10-29-2006, 02:17 AM
You should include screen-shot..

It sounds like OpenGL problem.. Does it also appears on rendered image?

JamesCurtis
10-29-2006, 09:38 AM
I just tried it myself in LW9. Opengl does show the error, but the render is clean!!

Here's proof!

danielkaiser
10-29-2006, 11:36 AM
What your seeing is an OGL error, been like that for years, not sure NewTek can do any thing about it. as long as it doesn't show up in your render don't worry about it.

Rick Pingry
11-02-2007, 10:32 AM
This is actually a problem in a variety of mapping situations, including spherical and UV mapping. LW handles it properly in the render. Unfortunately, I am using this for a game and I use OpenGL, so I am seeing the same problems there. I know this may not be an issue specifically with LW, but does anyone know a work around?

Sensei
11-02-2007, 10:46 AM
Here's proof!

This is result of having one UV per one vertex, independently from polygons..

What you need is forget about vertices that are reused many times by surrounding polygons, and export your object (or load LWO, if you're using file directly) and scan polygons, for each polygon point use UV function which is taking both LWPntID and LWPolID and store such polygon as one piece.. NO MORE VERTEX INDEX! In OpenGL routine which is drawing polygon, just call glColor3d(),glNormal3d(),glTexCoord2d() and glVertex3d()..

Sensei
11-02-2007, 12:47 PM
Alternatively, if you want to have vertex indexes and re-usage of point, you will need to treat polygons with discontinuous UV points differently - basically they need to have copy of original vertex with discontinuous UV that's replacing original continuous UV (using above description). Polygons with the all continuous UV points will be processed like they're now.

iconoclasty
11-02-2007, 03:01 PM
Correct me if I'm wrong, but this is not an issue exclusive to LW. Seems like back in my 3ds days Max did the same thing.

Sensei
11-02-2007, 03:06 PM
It's every app issue which is not handling discontinuous UV properly at OpenGL displaying time - I can understand that, because it's slower..