Flipping Normals

DELFTship forum Hull modeling Flipping Normals

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    • #38245
      giorgio zuppin
      Participant

      Just refining a file to save it as future memory, when something strange happened:
      DS (latest free version), considered all layers, except the keel, in need to flip normals inward and so it did indeed, sending all hydro calcs to PsycoAsylum.
      Of course I checked out every possible fault: nothing changed, even the “check model” tool says the same – flip normals –
      So it’s my fault but what???
      Here’s the file.

      Thanks in advance, Jurgen.

    • #38246
      giorgio zuppin
      Participant

      Got some clues, maybe…
      I checked the similar file, posted in “klinker” – general question – by myself, and it has the same issue.
      Now I can argue that trouble is caused by the peculiar grid arrangement, somehow folding itself, i.e. changing workplane
      in a small space thus confusing DS.
      It’s intriguing, need some help from local Gurus…
      Bye, Jurgen.

    • #38247
      Robert Holme
      Participant

      Yes, I think it has a brain fart because the normals relating to a plank are in 2 planes.

      Best Regards
      Bob

    • #38248
      giorgio zuppin
      Participant

      Stinkin’ awful, Gone all my dreams to draw a fleet of Drakkars!
      Talking posh, I’m not so convinced: planks not to be confused with faces and every face lays in his one and only plane.
      Thanks anyway, Jurgen.

    • #38249
      Robert Holme
      Participant

      OK ,what happens if you put each face of the planks on its own layer.

      Just a thought.

      Bob

    • #38250
      giorgio zuppin
      Participant

      All right, I care all opinions even from an old Krakatoa:

      Forget leak points, they are on boundary of hydro layers, so irrelevant.
      Any face on different plane set to different layer: nothing happened.
      Must be some Very Very stupid bug I’m not able to see…
      A confused Jurgen.

    • #38251
      giorgio zuppin
      Participant

      P.s.: “Krakatoa” Indonesian Vulcan known as quiet dispenser of savioury pearls also capable of erupting nasty sentencies…
      Manaste, Jurgen.

    • #38252
      giorgio zuppin
      Participant

      Sorry, I’m giving up.
      Still no clues why DS corrects normal’s direction in this and only file, baffled.
      But a man CAN draw Drakkars, well a sort…

      That’s all Folks.
      Jurgen.

    • #38254
      Marven
      Keymaster

      You’re correct Jurgen, this seems like a strange coincidence of circumstances.

      In order to ensure correct facing of the surface normals, the normal of the lowest point of the hydrostatic layers should point down. Based on this assumption the rest of the normals is calculated.
      In this particular model that point is at the bottom of the stern skeg, on the rounded corner to the transom. I think that by making this edge a crease edge your problem will be solved.
      Image1_2016-04-21.png

    • #38255
      giorgio zuppin
      Participant

      Thanks a lot but, and now I’m on a slyppery way…or skating on thin ice (more Dutch-like):
      It seems like the Tutankhamon curse is at work – the image you’ve sent is of the NewKlinker.fbm model…
      All the fuss is about TenderKlinkerStyle.fbm – Message#4610:
      in this pic you can see the normals at lowest faces of hydro layers correctely pointintg outwards
      (just moved apart the keel for better wiewing)

      Now have a look at what happens with “Check Model”

      ………..?
      A still confused Jurgen.

    • #38258
      giorgio zuppin
      Participant

      Thak you for kindly reply but, (I’m skating on thin ice now) your attachement belongs to Newklinker.fbm.
      All the fuss has started with TenderKlinkerStyle.fbm – message #4610 –
      in this pic the correct direction of the normals (on the lowest hydro layers) can be seen:

      TKSA.jpg
      Now This happens when you run “Check Model” in Tools:

      TKSB.jpg
      ….?
      Crazy is’nt it?
      Fact is, in this one and only file it occurred, some fault in it makes the program misjudge normals direction.
      The keel was set apart for better wiewing; anyway your tip about criteria of hydro calcs is prizeless and worth itself a thank.
      For the issue, I don’t know, it’s like a Tutankamon Curse, even on my reply strange facts heppened and I was forced to delete attachements etc.etc..
      Jurgen.

    • #38262
      giorgio zuppin
      Participant

      Solved! And your suggestion was Correct (what else it could be ?).
      Because the model was a fast arrangement on a file often used as a sample, the hull construction was peculiar And strange.
      So the lowest face of the hull – hydrostatic layer – had the normals pointing Out – lateraly – Not Downward!
      Just added a flat 0,005m. section all around, then moved everything back by the same amount.

      T1.jpg
      Now normals are facing Downward:
      T2.jpg
      All’s right again under the sun and I can proudly say:
      DScaption.png
      (copyright Matt and the Telegraph).
      Jurgen.

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