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Thread: Modeler Artifact when Concave Polygon Extruded

  1. #1
    Alliterator
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    Modeler Artifact when Concave Polygon Extruded

    Hi Gang,

    I'm brand new to LW, so sorry if this is a frequent question:

    I've drawn a polygon, using the Pen tool, that has a few concave corners (it's basically an octagon with the top and bottom edges extended from the bases).

    The original polygon looks fine. However, when I extrude it, I get a display artifact across one of the concave corners in the extruded endcap. The artifact doesn't appear in Layout, just in Modeler (and there only in shaded views).

    Any ideas?

    Screen shot and sample lwo attached.

    Windows 2000 SP4, P4 3.2GHz, 2 GB Ram, nVidia 5200

    Thanks,
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    -fyrissian-

    "go flaccidly amid the poison waste"

  2. #2
    How Old? Really? Aww Heck colkai's Avatar
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    worry not - this is just an OpenGL glitch, it will render fine and hasn't actually affects the geometry - as you can tell from teh views in wireframe mode.

    To prove it, simply triple the polys with more than 4 sides and you should see it disappear. If it really bugs you, just cut the polys so they are made up of quads / tris, but it isn't really necessary.
    Too old to die young.

  3. #3
    Alliterator
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    Okay, thanks! A cursory search didn't reveal anyone else having the problem but I didn't think to check using OpenGL as a parameter....

    "We applied the cortical stimulators, but there was no response from either patient."
    -fyrissian-

    "go flaccidly amid the poison waste"

  4. #4
    If you relly want to correct the model, you can (K)ill the offending poly. copy the points to new layer, select in sequance, hit P to create new poly. Then cut & paste into origional layer, finally merge points.

    May sound like a lot of messin arouind but took about 8 seconds in practice.

    Rich

  5. #5
    Super Member Silkrooster's Avatar
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    I had to try this, and yep I get that artifact as well. I don't think it is so much a gl bug as I think it is more of a lightwave bug. When using the pen tool, that a offending artifact shows, but not on the extruded polys. By killing the poly and selecting each poly in order and using the make poly command, the artifact disappears. Also If you leave the poly alone and bring it in layout, the poly shows correctly. I beleive if it was a open gl problem it would also show in layout. It seams to me that modeler thinks the point order is not correct and shows the artifact. Which explains why killing and making poly works correctly.
    I guess at this point this is all guess work as to why this happens, only Newtek can really answer this. At least there is no harm whether you leave the poly alone, or fix it.
    Silk
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  6. #6
    How Old? Really? Aww Heck colkai's Avatar
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    Actually, a faster way is to simply select it, triple the poly, then merge polys.

    BTW - when I said OGL bug, I just meant that it hadn't actually upset the geometry in any way.
    Too old to die young.

  7. #7
    obfuscated SDK hacker Lightwolf's Avatar
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    Quote Originally Posted by colkai
    Actually, a faster way is to simply select it, triple the poly, then merge polys.
    Or, in shorthand:
    shift-T
    shift-Z



    Cheers,
    Mike - who has todo this too often...

  8. #8
    How Old? Really? Aww Heck colkai's Avatar
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    hehe - yeah..that
    Too old to die young.

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