# How to deform a surface 3-dimensionally with two curves

I was trying now for a few hours, no chance. As seen on the screenshot, I want to deform that triangle 3-dimensionally so that it looks a bit like a tent. The red marked edge and vertex on the opposing side (the anchors) have to stay right in place because I apply other modifiers in the next steps. I too apply the Mirror Modifier which is active on that screenshot.

I want to deform it as follows: the orange edge has to be deformed on the "Z" and "Y" coordinates to get the shape a little bit like the yellow curve. Same with the turquoise edge to its corresponding curve on the "X" and "Y" axis. The rest of the vertices have to follow proportionally. Well... I tried it manually by proportional editing, but that would be very difficult to achieve what I want.

EDIT: I edited my question so it would be understandable without a picture.

• With a simple shape like that, couldn't you start the modeling process with the curves that you want and bridge the loops? Commented Jan 3, 2021 at 16:16
• Hello, thanks for your answer. That would be an option but didn't try it yet because I assume that the surface would still be (almost) flat and 2.) as far as I know, two different curves produce two different amounts of vertices, so I would have to tinker. I imagine there is a lazy/pro way I would like to get to know. EDIT: Also I apply 4 other modifiers on top of that, so with that imagined way I would still have control over the result. Commented Jan 3, 2021 at 16:21
• Do you have an end-goal reference image that you could add? Commented Jan 3, 2021 at 17:20
• Yes, here: blender.stackexchange.com/questions/185584/…. I have everything of that ornament done except the defoeming of the end cap. Commented Jan 3, 2021 at 17:42

Ok, a triangle with one straight edge, two concave edges, and a concave bridge between them.

Let's start by making a triangle out of a plane like this:

Then delete only the face by selecting everything and pressing X, N.

Using individual origins (. for pie menu), scale the edges up until the corners are close enough to merge.

Press M and merge by distance. Increase the distance until the message at the bottom shows 3 vertices have been removed.

Select everything and fill with F.

Holding Alt, click twice on a boundary edge to select the whole boundary. You can then set the edge creases to 1 with ShftE.

Tweak the vertices to your liking and you will get something like this:

If the normals are flipped, in edit mode, just press ShftCtrlN to calculate the normals to face opposite the "normal" direction (since the mesh is concave).

• Can I get yet some concave curves into that surface? Commented Jan 4, 2021 at 11:45
• Like have the bottom edge curve inward? Commented Jan 4, 2021 at 18:50
• Got ya, a change like that would be done best with different topology though. It's pretty tricky sometimes to get nice curvature on 3 sided surfaces. (Although, I may be too much of a perfectionist since I'm into modeling cars.) Commented Jan 5, 2021 at 17:49
• Basically, a different structure of polygons across the surface. Like ico sphere vs UV sphere. Not necessarily quads vs tris though. Quads are usually better. Commented Jan 5, 2021 at 19:01
• Edited answer. It should have really nice looking curvature with the new topology. Commented Jan 5, 2021 at 20:45