Flow Along Surf problem


I posted this in the brazil forum and realized too late its in the wrong place.

I am doing my best to overcome the learning curve and have come across something that has me baffled. I have drawn a stacked group for the side of a ring, when I do the flow along surf the stack goes right where I want it but it stretches as it is applied. I have included a screen shot and am in hopes someone can tell me just where I am messing up.

Thank you in advance

All my best … Danny

(John Brock) #2

I think FlowAlongSrf is stretching because your target and base surfaces do not have the same untrimmed length and width.


It appears that your target surface here is a developable surface. If you unroll it, place your geometry on it, and then use the unrolled surface as your base surface for FlowAlongSrf (instead of your pink plane), it should work better.

There’s been some kind of funny business with UnrollSrf lately, so UnrollSrfUV may work better for this. Also note that you may have to use Dir to swap U and V on the unrolled surface, because sometimes it switches it when it unrolls for some reason.

(Pascal Golay) #5

Hi Danny - OrientOnSrf (Rigid not checked in the dialog) may work out better here. Otherwise, make your base surface,(purple) narrower. FlowAlongSrf will work with History, so you can taper the purple base surface, or just make it narrower, as needed (not by trimming but by scaling or point editing) after the fact, until it looks right if you use History.

I attached an example that shows how the relationship of the object to the base surface affects the results- note that it is always the underlying surface that counts, not the trimmed face.
One example has History, so you can noodle the blue surface (make it wider and narrower say, or taper it with point editing and see how that affects the result.

FlowAlongSrfTest_PG.3dm (259.0 KB)



Pascal and John,
Thank you for your input. Pascal I opened your test example and it helped me see what you meant. It ended up that I needed to narrow and lengthen my surface the move the object to the right end, only had to try twice and it worked like a charm.

I have had Rhino for awhile but just got a new computer that is much faster than the old one. I told my daughter that I was going to design her five different rings so she could pick the one she likes best, in doing this I figured it would make me more confident and comfortable using this wonderful software.

Thank you again … Image attached … All my best … Danny


I tried what you said and because there are two curves unroll would not execute.

Thank you for your feedback.

All my best … Danny


Thank you for telling me about UnrollSurf just used in on a flat surface and I put seven stones in place like magic.

All my best … Danny