# Creating 2D linework of unrolled non planar surface

Hello! im finishing a competition and need help pulling line work from a model in a specific way. My form is multiple arced surfaces and im trying to create a 2D drawing as if the model unrolled or flattened. Ive been trying to use the unroll and smash command but it has not worked the way i expected. Any ideas on a way to do so. I am familiar with make2d.

Hello - it may be enough to unroll one of the faces, front or back - can you post an example, or send to tech@ mcneel.com with a link back to this topic in your comments?

-Pascal

arc.3dm (4.9 MB)
Here is a part of it. I think theres a chance there might be something wrong with the modeling because theres space between the frames so maybe even though its a closed form on one side but space between on the other its not reading as unified? just an idea though.

I tried Cplane and its very close to effect im looking for but im still trying to “untwist” the part on the bottom so that its shown in the flatten and not projected over like so

bottom part is the 2d flattened surface

Am I correct that in theory, these are 2d structures, but deformed? If so, there is a way to get there, or in that direction, starting from your file but your file has these gaps that need to be accounted for…

-Pascal

ya these gaps are another thing im trying to figure out. I’m in the process of trying to think out how to do it with the cuves i have in my grasshopper scipt. Its closed on the back end but open on the other side but yes in theory they are 2d structures that are deformed.

In that case the triangulated structure will not have ‘square’ members or holes. Is that part of the plan? Or is it non-deformed triangles moved and rotated onto this twisty form?

-Pascal

By quare members i think you are refereeing to how its separated into 5 pieces, 2 for each side of the polyarc with a middle connection between the 2. The idea of them being its these pieces would be for assembly and dismantling. But the gaps in the frames isn’t apart of the design i intend to close them

I was just thinking that if these are assembled flat from square or rectangular members then when moved into position there will inevitably be gaps on one side, or, the triangles’ beams will each need to be custom mitered to meet up properly on both sides.

-Pascal

If its inevitable to be gaps then thats alright. The design isn’t a built pavillion but its a conceptual proposal for a student competition. I’m trying to make it as close to real as i can get it. So the idea of this 2d drawing of it unrolled is so that i could add in dimensions and make assembly diagrams showing that theres 5 pieces. I guess one way i could do it is by taking out the angled part from the script but i feel like that would change the actual dimensions.

But i see what your saying about how each gap would need to be custom fit so having gaps makes more sense then not

I would get this surface:

UnRollSrfUV and then FlowAlongSrf your objects from the 3d to the 2d surface.

-Pascal

oh thats actually a great idea i didnt think about let me try it real quick

im struggling with the flow along srf command. when I do it and i select my objects it has me select a corner but then i cant select another corner bc the entire surface is already selected

For `FlowAlongSrf`:

1st selection is the objects to be flowed. Do not include the base surface in this selection. Pre-selection is OK.
2nd selection is the base surface, near a corner
3rd selection is the target surface, near a corresponding corner.

Does that make sense with what you are seeing?

-Pascal

yes when i go to select the base edge it selected the entire surface rather then a corner or a edge. Which prevents me form selecting a second edge.

Select the base surface edge, then the target surface edge at a corresponding location - two separate surface selections on different surfaces…

-Pascal

is this what i should expect from that or should i be completely planar?

there we go this is perfect and planar not sure y it didnt want to work on the other smaller pieces though.