how can i tell if two surfaces are parallel?
Measure the angle or compute the dot product…
If the angle between two surfaces is 0, the surfaces are parallel.
1 Like
Thankyou Martin
but in rhino you can’t measure the angle between surfaces can you?
note the surfaces to measure might be round or irregular shapes at times..
Set CPlane on the first surface, then create the boundingbox of the second one.
If the resulting box height is under tolerance, they are parallel.
Curved things cannot be parallel.
I know what you mean, but on a broader term an offset surface would be parallel, however your proposed way of checking would also work.
Populate one of the two surfaces with a number of points and find the closest points on the other surface. If all distances are the same, the surfaces can be parallel
2 Likes
Curved things cannot be parallel.
They can be if they are 2d shapes parallel to each other, I.e a can of beans has a round top and bottom that are parallel to each other
A 2d shape isn’t curved
I did say round or irregular shapes 
Good luck.
Here is a rudimentary script that might help. It needs some refinement, it’s late here, I can look tomorrow.
CheckSrfsParallelPlanes.py (1.1 KB)
Hi Jeremy
Thankyou, what command did you use to get that?
Hi Adrian,
It’s the _Angle command but you have to select the TwoObjects option or preselect two surfaces.
Regards
Jeremy
2 Likes