# Correctly filling a convex and concave mesh from curves

I need to make curving concave and convex meshes, while at the same time, expressing the mesh data as only quads. (Quad meshes work well with subdivision, smooth shading, and bevel, but triangular or n-gonal meshes don't work with all 3.)

The nature of being both concave and convex thwarts making quads going completely vertically or horizontally and similarly messes with the almighty grid fill. I had no luck converting this mesh from a filled 2d curve, since the curve is filled with triangles that cause shading artifacts. So I tried manual work, revealing it is indeed impossible to fill with quads in a purely vertices/horizontal manner. An n-gon fill doesn't work, and the last image shows that grid fill has issues even at its best. I also tried smoothing vertices on all methods, and it got the grid fill method pretty close.

I could use workarounds, like using flat shading on the flat side of the axe with an autosmooth modifier, but I want subdivision and smooth shading.

(When extruded out) how can I fill this mesh in a way that doesn't cause smooth shading artifacts?

• This is quite complex case for grid fill to work out of the box. You could fill that ugly Ngon for beginning, inset it a bit and get good shading around edges. After that I think you will still need to figure out a way to get rid of that Ngon - again GridFill or joining verts located opposite to each other with J. Sep 11, 2016 at 9:34
• I think that quad-only property is not enough to ensure good subsurface and bevel: you'll have to keep an eye on edgeflows too. Probably retopology is the best way to approach this task. Sep 11, 2016 at 9:53

You should retopolgize this mesh. It is pretty simple with method I will present (if this kind a mesh will suite you).

1. First of all you should make a plane and position it at the bottom of the blade.

2. Then extrude it all the way up.

3. Select loop and extrude to the end of axe scaling down each loop.

This gif shows the retopo flow:

If you need more detailed description, let me know in comment what do you need.

Edit:

• Hmm. You mean I should make a plane in edit mode with the vertices active, right? I made one out of the three vertices at the bottom of the axe (the first face your gif highlights). I understand step 3 fully, but I wasn't able to get a uniform appearance by extruding that plane. At least, not one that curves like all the faces you have on the edge of the axe. I'm new to retopology. Sep 11, 2016 at 15:43
• Make a plane in object mode, then go to edit mode and extrude edges of this plane. Gif is showing only edge flow of the mesh, not actual steps. Sep 11, 2016 at 15:45
• top-down, orthographic view I'm assuming. I'll give it a shot. I'm guessing you had to adjust the edges of the first face as you extruded more from it so that the faces were curving properly. Sep 11, 2016 at 15:46
• I'm using front ortho. Yes, you need to set vertices of the first plane as shown in the gif, kind a diamond look, then select right-top edge and start extruding. When you make the blade, select left edge loop (alt + right click) and extrude this to the left. Sep 11, 2016 at 15:49
• Set the image to pivot/scale around the 3d cursor to avoid this (imgur.com/nT90A0u). Use ctrl + shift + alt + S to shear to match the nearby vertices as best as possible. I got it :) Sep 11, 2016 at 16:05