 | | Re: Finding a rotation matrix for a triangle
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(...) Hi Niels, I'm not sure exactly what you mean by the rotation vector of a triangle? There isn't really one as a triangle is defined by three points (9 components) whereas a rotation matrix/vector is defined by only 1 point (3 components). A (...) (19 years ago, 27-Nov-05, to lugnet.cad)
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| | Re: Finding a rotation matrix for a triangle
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What I mean is: In MLCad, you can take a part, and rotate it via a vector command like turn 45 degrees around y axis clockwise. Or more complex rotations based on more axes. What I would like to know is: How do I find the rotation vector of a plane (...) (19 years ago, 28-Nov-05, to lugnet.cad)
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| | Re: Finding a rotation matrix for a triangle
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(...) Hi Niels, I think you are getting two things a little crossed here but I will try to answer you questions. Firstly, you must remember that a plane can be defined meaningfully by a normal vector (one perpendicular to the plane) and a vector (...) (19 years ago, 28-Nov-05, to lugnet.cad, FTX)
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| | Re: Finding a rotation matrix for a triangle
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(...) You take the cross product of two of the sides of the triangle, this will give the vector perpendicular to the triangle plane: (URL) will point either upwars or downwards. Unless your triangle is in a known winding state there's no way to (...) (19 years ago, 28-Nov-05, to lugnet.cad)
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| | Re: Finding a rotation matrix for a triangle
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(...) Heh, probably ;-) Well, perhaps I got the math part, and definition process a bit mixed up: I'd just like to have a program that, from a three coordinates on a plane, can give me a rotation vector+angle that I can enter in MLCad... And I'm a (...) (19 years ago, 29-Nov-05, to lugnet.cad, FTX)
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| | Re: Finding a rotation matrix for a triangle
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(...) Hi Niels, There isn't really a meaningful way to get an angle out of a plane defined by three points. What would the angle mean? The xyz, angle formula in MLCad just says rotate the vector angle degrees around the vector xyz but in the case of (...) (19 years ago, 29-Nov-05, to lugnet.cad)
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| | Re: Finding a rotation matrix for a triangle
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Thanks for the formula Anders Do you have any idea on how to convert it to the vector type used in MLcad? (xyz+angle)? Cheers NB (19 years ago, 1-Dec-05, to lugnet.cad)
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| | Re: Finding a rotation matrix for a triangle
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(...) The angle of the plane defined by the three points: I need to slap a primitive directly onto the triange with the correct angle. Now, if I should only slap this edge-primitive onto some rect-primitive, I should be able to copy the angle (...) (19 years ago, 5-Dec-05, to lugnet.cad, FTX)
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| | Re: Finding a rotation matrix for a triangle
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(...) Now I think I see what you mean. You want to know how to rotate the primitive so that it lines up with one of the edge lines of the triangle. (...) This isn't the best way to go (I'll explain at the end of the post). (...) OK. The problem here (...) (19 years ago, 5-Dec-05, to lugnet.cad)
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| | OK here's the real problem! (Was: Re: Finding a rotation matrix for a triangle)
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Well, I think I've tried to explain what I need to do 3-4 times already, which is where I think the language barriers have played a pretty big role... The reason I tried to cook the problem down, is to reduce confusion, but I guess that was a bad (...) (19 years ago, 6-Dec-05, to lugnet.cad, FTX)
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| | Re: OK here's the real problem! (Was: Re: Finding a rotation matrix for a triangle)
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(...) I think my interpratation from the last time was halfway there and this explains it much better so we're definitely getting somewhere faster now :). You should be able to use the formula I gave in the last reply instead of an XYZ+angle in (...) (19 years ago, 6-Dec-05, to lugnet.cad, FTX)
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| | Re: OK here's the real problem! (Was: Re: Finding a rotation matrix for a triangle) [DAT]
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(...) Take the edge line: 1 2 -30 4 10 -3.69552 0 -1.53073 0 1 0 1.53073 0 -3.69552 1-4edge.dat Put it in a separate subfile. Include that subfile with no rotation matrix. Now apply a new MLCad rotation to the subfile. Finally inline the subfile to (...) (19 years ago, 6-Dec-05, to lugnet.cad, FTX)
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| | Re: OK here's the real problem! (Was: Re: Finding a rotation matrix for a triangle)
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(...) Actually, what you need to do is *skew* the 1-4edge. Literally deform it, so it stretches along the edge of the stud3 cylinder. If you turn it, it will no longer intersect the surface of the cylinder -- the edge will disappear inside the (...) (19 years ago, 6-Dec-05, to lugnet.cad, FTX)
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