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Subject: 
Re: Finding a rotation matrix for a triangle
Newsgroups: 
lugnet.cad
Date: 
Mon, 5 Dec 2005 13:41:17 GMT
Viewed: 
1724 times
  
In lugnet.cad, Timothy Gould wrote:
   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 a triangle, what would that angle be?

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 directly. But since triangles aren’t defined by rotation matrix, I thought that the triangle would need to be converted into something that is (like a plane)

   If you are thinking of a specific way of obtaining the angle from the triangle, please let me know and I can work out the formla for you.

It would be really great to have a formula where you can enter the three coordinates of the triangle, and have an output in the form of the numbers that need to be entered into the xyz+angle-formula in MLCAD.

-To put my edge primitive at the excact same angle as the triangle.

I hope that made sense...

   One thing that can be done is to find an orthogonal basis set which spans the plane which might be useful. If this is of interest to you I can write some code for it.

I’m not sure what you mean by this: language barriers seem to be a big problem in this discussion - but I’m really grateful that you wish to help me...

Cheers NB



Message has 1 Reply:
  Re: Finding a rotation matrix for a triangle
 
(...) 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)

Message is in Reply To:
  Re: Finding a rotation matrix for a triangle
 
(...) 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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