Most efficient way to lay down flat

Lay down flat.3dm (105.8 KB)
I’ve got a file attached with a flat trapezoid-shaped surface on it that is hovering over the origin point at an angle. This may seem like a simple exercise, but I am wondering what is the most efficient way to lay it down flat (so that it is perfectly horizontal) without distorting it… using Smash etc.

Is there a simple workflow for doing this, or would a script be able to take the four corners and bring them down to 0?

Thank you.

Hi Cosmas - using Rhino commands, the best would be - set a Cplane to the object and then, assuming it is planar, RemapCPlane, with the CPlane option and type in Top as the CPlane.


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Thank you, Pascal!

Another fast way is to use unrollsrf. The backface determines which side will face ‘up’ when the surface is unrolled at 0,0,0

Hey Cosmas. Would ‘Orient3pt’ not also work, assuming that the c-plane is set to ‘world top’?


orient 3pt is how i usually do it. i find it easy but there may be easier ways for sure. im still new with many of rhino’s functions.

All excellent solutions. Thank you : )

Just a little sidenote on the unrollsrf technique. If you didn’t pay attention to the backface settings, then mirroring it to the other side of will flip the object over and will effectivelt make that the surface normal too.

So, you can undo, and flip it, then unrollsfc again or

only having done the command the first time, you can mirror it across y axis, and it will flip it over and change the surface normal.

So, basically to sum it up. If it doesn’t unroll on the grid as you wanted, just mirror it. or undo, flip and redo.

The labels sure help a lot!

Also, cosmas I don’t know if it was just a sample file, but changing your backface color (in each view) to something noticeable will definitely help out troubleshooting commands that don’t behave how you intended for them too.

Luckily, this surface was planar. AT first I thought it wasn’t. Therefore, I think I would like to get in the habit of using unrollsrf over the orient3pt.

Unroll sfr on a non planar version of the sample(move 1 control point) would unroll it flat, orient 3 pts would not. So its cool that unroll srf works on planar surfaces and is a additional function to move a flat surface to the world x,y grid real quick. Lets say you were playing around in rotaing, and got lost. Instead of measuring angles, etc…you could just do unroll sfc and move it back to where you were before you got lost in rotation.

Love it. Thank you!

Say, I noticed your notes in the files Cosmas. Did you get any good suggestions to flatten 1 part of a doubly curved surface? I had misinterpreted extruding in 1 direction, and played around to see if that would give a wireframe that is only singly curved or something.

Even though I haven’t really searched for this yet, anyone have any good methods of laying 1 curve direction flat on cplane, and the other to be worked on/left alone without warping? So that unrollsrf gives good results, or basically unrolling each curve direction isolated? Or to be able to unroll each curve directions, good, without warping or projecting?

No, I haven’t. Is that really doable? Like a flattened globe?