 | | LDraw coordinate system driving me crazy —Roland Melkert
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| | | Hello all, I'm having difficulties with the ldraw coordinate system. As fas I understood it it's Right handed, just like OpenGL. So X positive is right X negative is left Y Positive is top Y Negative is bottom z Positive is front z negative is back (...) (17 years ago, 19-Nov-06, to lugnet.cad.dev)
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| | | | | Re: LDraw coordinate system driving me crazy —Ross Crawford
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| | | | | (...) I've always understood it is: X positive is right X negative is left Y Positive is bottom Y Negative is top z Positive is back z negative is front In fact you can show this by adding a brick in MLCad and moving it around, watching how the X, Y (...) (17 years ago, 19-Nov-06, to lugnet.cad.dev)
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| | | | | | | Re: LDraw coordinate system driving me crazy —James Reynolds
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| | | | | | As I understand it, LDraw has negative y in the up direction, which is neither right nor left handed, but something else entirely. I don't know that it has a name. James (17 years ago, 19-Nov-06, to lugnet.cad.dev)
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| | | | | | | | Re: LDraw coordinate system driving me crazy —Timothy Gould
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| | | | | | (...) It is still a right-handed system. The handedness is unchanged by rotation (in ldraws case 180*x from standard). Tim (17 years ago, 19-Nov-06, to lugnet.cad.dev)
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| | | | | | | | Re: LDraw coordinate system driving me crazy —Roland Melkert
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| | | | | | Tim Gould wrote: > It is still a right-handed system. The handedness is unchanged by rotation (in (...) So the original designer of the LDraw program just decided to use this orientation of the right handed system. if so then it starts making more (...) (17 years ago, 19-Nov-06, to lugnet.cad.dev)
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| | | | | Re: LDraw coordinate system driving me crazy —Jim Foltz
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| | | | (...) I've been having difficulty with importing/exporting .dat files from SketchUp. In SketchUp, if you stand at the Origin; X is right, Y is forward, and Z is up. The LDraw Primitives Reference ((URL)) says the LDraw axes are: X is right, Y is (...) (17 years ago, 19-Nov-06, to lugnet.cad.dev, FTX)
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| | | | | | Re: LDraw coordinate system driving me crazy —Timothy Gould
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| | | | | (...) In LDraw +z is backwards, not forwards or more strictly +Z points away from the camera when X is right and -Y is up. Tim (17 years ago, 19-Nov-06, to lugnet.cad.dev, FTX)
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| | | | | | | Re: LDraw coordinate system driving me crazy —Jim Foltz
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| | | | | | Hi, Here's my box test model in SketchUp. (The above model is the same model unfolded.) (URL) When I export this model to a .dat and open it in LDView, the green side is the top-view, blue is the front view (as expected), and I would expect the (...) (17 years ago, 19-Nov-06, to lugnet.cad.dev, FTX)
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| | | | | | | | Re: LDraw coordinate system driving me crazy —Timothy Gould
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| | | | | | | (...) That looks like a correct mapping to me. Unless I'm mistaken the red and orange are on the same sides in both pictures. The unwrapped boxes are definitely identical and unless you've moved them in one or the other the whole thing is right. Tim (17 years ago, 19-Nov-06, to lugnet.cad.dev, FTX)
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| | | | | | | | | Re: LDraw coordinate system driving me crazy —Travis Cobbs
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| | | | | | | | (...) I agree with Tim. It looks fine to me. If there were any mirroring going on, then either the orange and red would be swapped on the unwrapped box, or the green and grey would be swapped. The picture in LDView has a rotated camera angle (...) (17 years ago, 19-Nov-06, to lugnet.cad.dev, FTX)
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| | | | | | | | Re: LDraw coordinate system driving me crazy —Roland Melkert
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| | | | | | (...) Google uses the right handed system but indeed rotated by 90 degrees, LDraw also uses the right handed system but 180 degrees rotated. It should not matter how you show the model, the coordinates are interchangeable, but if you want to use (...) (17 years ago, 19-Nov-06, to lugnet.cad.dev)
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| | | | | | Re: LDraw coordinate system driving me crazy —Jim Foltz
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| | | | A sincere thanks to all of you. Your comments made me go back over (again) my export code, and I found an error. Now it works as expected. I was getting funny rotations because I mis-ordered the elements of the transformation matrix, duh. Seems (...) (17 years ago, 20-Nov-06, to lugnet.cad.dev, FTX)
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