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FS2004 Polygon concave

Discussion in 'Tools programming' started by Buite, 16/2/12.

  1. Buite

    Buite

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    Is FS2004 able to use concave Polygon?

    All my convex polygon are good in TmfViewer but all my concave polygon are bad, so I think probably FS2004 doesn't use concave Polygon.
  2. Buite

    Buite

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    It's ok I've fund my problem.
  3. hcornea

    hcornea Resource contributor

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    Always good to share the solution, having asked a question.

    It might just help someone else.

    I'm still unsure about what convex vs concave polygons might be.


    Sent from my mobile .. words substituted by iPhone at will.
  4. Golf-HotelDelta

    Golf-HotelDelta

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    Think of a "V" shape (concave) versus an "O" shape (convex).
  5. Buite

    Buite

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    I had just forgive one point, so I hadn't the right number of point and TmFViewer want the right point's number.
  6. hcornea

    hcornea Resource contributor

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    Yes, I believe I know what the words mean, having more than a rudimentary understanding of optics (!) just not sure how they relate to land polygons (which in my brain are either sloped or flat -- this may, of course, be an FSX thing)
  7. rhumbaflappy

    rhumbaflappy Moderator Staff Member Resource contributor

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  8. hcornea

    hcornea Resource contributor

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    Interesting Dick. I guess I had considered all poly's to be flat / triangulated things.

    Since you can only define an "edge" i hadn't really considered any other shape.


    Sent from my mobile .. words substituted by iPhone at will.
  9. Golf-HotelDelta

    Golf-HotelDelta

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    In FSX, vector polygons need be neither flat nor convex.
  10. hcornea

    hcornea Resource contributor

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    So ... a concave polygon is defined by having a point lower than its two neighbouring points ... the induced depression producing (at least in theory) a concavity.

    Hmm ... it is a moot point for me as I don't develop for FS9 at all.

    It seems to me that this is the only concave shape that you could define by edge-vertices alone.
  11. rhumbaflappy

    rhumbaflappy Moderator Staff Member Resource contributor

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    Concavity was quite an issue when drawing VTP or LWM polys for FS9. Luis Sa spent a bit of time coming up with code in SBuilder to triangulate the polys so they would not have concave shapes. I don't believe Luis' code is 100% all the time. FS9 doesn't allow holes either. I do note that there are some default concave shapes in the default LWM polys... but nothing complicated. The assembly code doesn't prevent it, but the display engine can get "confused" by it.

    In FSX, Shp2Vec handles the code, and does a great job of eliminating the problem.

    Dick
    Last edited: 17/2/12
  12. Golf-HotelDelta

    Golf-HotelDelta

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    No.

    How about this top-down view? It is a 'concave' shape with different heights at each vertex.

    [​IMG]

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