# 3D Math

This is a question for those who use trigonometry in Blender modeling. I want to place a long, thin object (like a plank or a girder) so that the ends are at two specific xyz points. Calculating the length (distance between points) is easy—sqrt(xx+yy+z*z). However, there are several different ways of calculating the angles in space. Which method is correct for Blender? I want to be able, to just punch the numbers into the “transform properties”, rather than trying to “feel” the piece into position, with the rotate command. Also, I would like to avoid using control-A.

Any other math whizzes out there?

Blender just uses standard Euclidean geometry (in degrees) for transforms, unless you tell it to use something else. You’d have to make sure it was set to Global though if you want to use global coordinates as your set points. If you try to transform when it’s set to Local or Normal or Gimbal it will screw things up.

So how do you want to “punch it in”? Are you going to calculate the angles first, then punch in the relevant number of degrees? Or do you want to be able to punch in coordinates and have Blender do the calcs for you? I think (not entirely sure) the latter might require an add-on.

If you have two end points, just key it in and create an edge. In Properties panel under Mesh Display, there is check box for Length and Angle display. The Length and Angle will be displayed over the edge.

OK, after a bit of experimentation, I finally found the simple process that I was seeking. With the object lying flat, with the two endpoints aligned along the X axis, rotate: Zrotation=compass heading; and Yrotation=azimuth.

I can write out the entire mathematical process, if anyone is interested.

Thanks all, for your help.