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Thread: Geometry problem ?

  1. #1
    Junior Member
    Join Date
    Oct 2009
    Posts
    5

    Geometry problem ?

    Hi,

    I'm trying to load the BikeFromXSI.dae file from :

    http://collada.org/owl/browse.php?se...0&sortname=ASC

    But I got a problem with the geometry when I try to calculate the normal,
    because I have 2 identical points coordinates for the same polygon :

    The geometry name is : "geometries_7"

    Polygon index : 1737 (index start at 0)

    in

    ...</p> at the 6948 (1737*4) index, I got the following vertices indexes :
    vertex indice = 828
    vertex indice = 107
    vertex indice = 802
    vertex indice = 2070

    And then the following vertices ...

    Here are the positions of the vertices :
    (-0,669677972793579, 0,797966003417969, 0,669677972793579)
    (-0,669677972793579, 0,797966003417969, 0,669677972793579)
    (-0,786494970321655, 0,797966003417969, 0,525873005390167)
    (-0,786494970321655, 0,797966003417969, 0,525873005390167)

    How it is possible to have several times the same coordinates for this polygon ?

  2. #2
    Senior Member
    Join Date
    Aug 2004
    Location
    California
    Posts
    771

    Re: Geometry problem ?

    Yes it's possible for a polygon to have coincident vertices. It's called a "degenerate polygon" and is almost always considered bad modeling (unless there is a non-visual reason for it to exist). In this case it appears to be a quad that is actually a line.

  3. #3
    Junior Member
    Join Date
    Oct 2009
    Posts
    5

    Re: Geometry problem ?

    Thanks for your answer,

    So, I can bypass all the polygons that have some Normals with lenght = 0.

    But the, I still have a problem when loading my Collada model, here is the result I got :
    http://picasaweb.google.com/viewon01...30633418058914

    Do you see that some face are not correctly drawed ? I search to fix this problem since several weeks without a solution, can you help me please ?

  4. #4
    Senior Member
    Join Date
    Aug 2004
    Location
    California
    Posts
    771

    Re: Geometry problem ?

    Continue what you're doing: isolate and debug the problem polygons to determine what the problem is in each case.

    Try using your favorite modeling tool to process and clean up the data and re-export it.

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