Hello everybody,
I have a problem with Rhino. I don’t know which command to use. I would like to model a wooden planking (as in the attached photo number 1) on a curved surface (as in the attached photo number 2).
Does anyone know which command to use for my project ?
The command “project” isn’t good for my problem.
Thanks a lot for your help !
Kind regards.
Hi Pascal !
Yes, it is ! How did you do ?
Marine.
Hi Marine - it is a bit of work… I’m not sure it’s the most brilliant solution but it might be close enough. I’ll try to outline the steps shortly here and you can see if it seems reasonable.
-Pascal
Ok, thanks a lot !
Marine.
Hi Marine - can you please post the surface you have and something to indicate the width of the planks?
-Pascal
Hi pascal,
Yes. I do it now. I sent it you in the second message.
Marine.
Hi Pascal,
Here the 3D file :
Test 3D.3dm (5.3 MB)
Is it possible to try with different directions ? If yes, how ?
Thanks a lot !
Marine.
Hi Marine - I see, hm, this is a little different, – how do want the planks to lie?
@Marine1 is this approximately right?
Test 3DPlanks_maybe.3dm (2.0 MB)
@Marine1 V5 version
-Pascal
Hi Pascal,
Yes, exactly !
How did you do ? 
Hi Marine - This may or may not be accurate enough - I see I did not use a ShortPath in my test, which makes a difference - I did use that on the cone example. The issue is, for a straight plank to lie cleanly on a surface it has to, I think, follow a geodesic curve, and I neglected to do that in this case.
In any case, either way, the base surface has to be G2 , curvature continuous, for this to work cleanly. Yours is several surfaces that are tangent (well not quite, but close) so you can see in my file that I recreated the surface from a single G2 curve that closely (please check ho closely, the curves are in the file) approximates your roof surfaces:
Now, using a geodesic (ShortPath command) make a curve in the direction of the planks - note that the curve will find its own way along the surface between start and end points. Note I made my surface oversized a bit too.
Now, OffsetCrvOnSrf the curve by the width of the plank - 20cm
Mark one end of both curves with points (the distance/direction from one point to the other is the distance to copy the plank when it’s done and you want to fill the entire surface) and then make lines perpendicular at the ends and Trim to make the ‘plank’
Now, Loft the curves together using StraightSections and Rebuild with maybe 24 points:
That is the base surface for one plank - by using ShortPath for the initial curve, UnrollSrf of this surface will make a straight plank - that is this shape can be created by bending a straight plank, which is what we want.
OffsetSrf > Solid = Yes to get thickness
Copy the plank as needed from one of the earlier marker points at the ends of the curve to the other.
@Marine1 - you can do this with your tangent surfaces but it is a bit more complicated.
-Pascal
Did you take that picture of the church tower planking?
It’s not my picture. I took it on this site : Rénovation d'une tour en ardoise à Cognac - S.A.S Toit Avenir, couvreur à Cognac Charente (16)
I hope it’s not a problem 
Tanks a lot for this explanation and for the time you spent on it 
I have some questions :
1- What is a G2 ?
2- How did you manage to get just one line ?
3- With the command “shortpath” : How do you find the final point ? Because I know just the first point and the direction in plan. But in that case, the direction in plan and on a curved surface, are not the same.
3- I don’t really understand the part " Mark one end of both curves with points (the distance/direction from one point to the other is the distance to copy the plank when it’s done and you want to fill the entire surface) and then make lines perpendicular at the ends and Trim to make the ‘plank’ ".
Thank you for your help !
Kind regards,
Marine.
Hi Marine - that is correct - the direction in plan, if it is a straight line, will result in a plank on the curved surface that is not derived from a straight plank. So you will be able to approximate the direction. Currently ShortPath does not have a preview, which makes it very harder to use in this context, if you want to match a particular curve as well as possible. I would Project the direction line onto the surface, and then use this script to draw the short path - possibly snapping to the ends of the projected line.
Blue = desried direction, projected from a line , Cyan = ShortPath snapped from one end to the other:
If you use this preview version it might be possible to come up with a compromise curve…
ShortPathEx.py (1.5 KB)
To use the Python script use RunPythonScript, or a macro:
_-RunPythonScript "Full path to py file inside double-quotes"
-Pascal
No it’s not a problem. I just find it interesting, very interesting actually!
