Plane Orientation

Can someone explain why (Plane 3pt) follows the unit vectors for the X direction (B / unit X vector) and Orientation direction (C / unit Z vector) when the origin (A) is 0,0,0.

But, when I change the origin (A) to the start pts of the curves in my "screen capture" the planes Z direction is not in the World Z direction.

Replies to This Discussion

Permalink Reply by Giulio Piacentino on January 21, 2011 at 6:24pm

Hi Greg,

Plane from three points creates a plane given three physical locations. It also accepts vectors, but these are numerically converted into the corresponding point (if vector was {1,2,3}, then point is {1,2,3}).

This means that the B point is now always {1,0,0} and the C is {0,1,0}.

Maybe are you looking for the normal Plane (Pl) component? It constructs a plane given start, X and Y axes (directions, that in this case then are vectors).

I hope this helps,

- Giulio

Permalink Reply by Greg J on January 21, 2011 at 7:12pm

Thanks Giulio,

It still doesn't make sense (I have very thick head). If my new C input is a unit Z vector, then Y (C input) should be {0,1,0} and in the picture above, the plane is rotated about the X axis approximately 45 degrees. Shouldn't the Y axis be vertical?

What I'm trying to obtain are planes perpendicular to the curves at the start point. Now that I think about it, a plane can not be perpendicular to a point. It has to be perpendicular to a vector, but A wants a point ....

Permalink Reply by Chris Tietjen on January 21, 2011 at 9:39pm