Hi All,

I can't for the life of me figure out how to control the orientation of these copies.
As I change the number of points on the line they flip randomly. Also if give the points normals it seems to have no effect…



Any ideas what I might be doing wrong?
Here's a link to the scene if anyone feels like checking it out.
http://www.peterleary.com/ForumFiles/Copy%20Direction-HXqH8d9wy3.hiplc [peterleary.com]

Thanks,
Pete

It is the slight offset you have in the x-direction of the line. Change -0.4 to 0.0 and the flipping goes away. If you really need your line to point in that direction you may want to follow up the copy with a transform to restore the rotation direction for the result.

But overall I might consider that a minor bug.

Hi Pete,

I remember wrestling with this one too. This is a great page to help sort what the copy SOP is actually doing: docs [sidefx.com]

The problem with the flipping is the polyframe SOP which is having difficulty figuring out which way the world is up (cross-product of two vectors with identical direction) . If you look in the priorities section of that page, you'll see what houdini tries to do when there aren't any ‘normal’ or ‘up’ attributes. If you take the polyFrame out of the equation everything goes stable again.

I've included a variant of your file with a wrangle node set up so you can see what effect each of the ‘normal’ ‘up’ and ‘orient’ attributes have. You may not need that to get it, but it helped me when I grasped those things,

Hope that helps

Hey thanks heaps for the help!