hi,
is it possible to rotate an object in 3d space, thus not only along a parallel of the X, Y or Z axis?
I have a simple plane, and it needs to align its normal (the green line) with the yellow line. it is for mirror projections, so it has to be very accurate.
now I have to rotate it first along the x axis, then the z, then x again and so on, but it never is spot on, always an aproxximation, since every rotation moves it away in the other axis a bit. always smaller deviation, but never perfect.

it would be nice to use the perspective view, select the green line and with object snap on, have it snap to the yellow line. but this does not work.

tnx
wim

Hi wim, you can use the Transform > Rotate > Rotate Axis rotation command to rotate around any arbitrary axis line in 3D space.

At the start of that Rotate Axis command you will pick 2 points to define the rotation axis. For your case there you would want to get 2 points on a normal going perpendicular to both those lines. To do that you could either set your construction plane onto the base of those lines and then drag the x and y axes of the construction plane orientation picker onto those endpoints, or also a quick way to do it is to drag out 2 construction lines from the base point along each line, that will then make a "normal" straight snap line available for your desired direction.

See here for an example of the quick construction line way:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4665.3

Basically 2 construction lines that come out from the same base point will form a temporary construction plane and you can snap along the normal of that plane , you want to use that to place the axis line for rotate axis.

Then the next steps for rotate axis are to either enter in angle value or pick 2 reference points - you would want to pick 2 reference points, one on each of your line endpoints.

- Michael

You can do this in three steps.

1) Draw a projection of your yellow line on the x-y plane, and also a line perpendicular to it (they are shown as blue lines). Also draw the green line in the image on the x-y plane.

2) Use the rotateaxis command to align your face as desired, as shown in the second picture. You should select the end points of the vertical green line as the axis to rotate about.

3) Use rotateaxis one more time, this time selecting the endpoints of the horizontal green line as the axis. Select the appropriate angle by picking the end of the vertical green line as the first reference, and the end of the yellow (orange in the picture) line as your second reference. The face normal is now aligned with the yellow line.

Dan

Thanks Michael and Dan for your prompt reactions!

Michael, your first method is a bit fuzzy to me, but don't bother explaining it otherwise, the second one is working for me, and I am glad I learned about the construction line trick!
Dan, your method is good, but also rotates the mirror along the Y axis, which is not desirable in this case.

but when reading all this, I suddenly realised I was focusing so much on the rotation aspect, that I forgot the orient tool, which beats the above solutions! simply select the plane and the normal line, select the orient tool and adjust base and target orientation. no additional construction lines to be made!

thanks, I wouldn't have found it without your solutions, and I learned a few things more about MoI!!!

rgds
wim

Hi wim, I'm glad you got it sorted now! And yeah I should have remembered the orient tool for that case myself - yes if you want to rotate a surface by realigning its surface normal to a different spot the orient tool is probably the easiest way.

- Michael