Cutting Up a Sphere

So, I’ve done some 3D modeling in the past but I’m relatively new to Blender. Here’s my problem: I’m trying to make something vaguely egg-shaped, but with a flat top and bottom. I decided to start with a sphere and stretch it. I found a method that other people have suggested that goes something like this:

  • in edit mode, select a loop of vertices going around the sphere.
  • Ctrl+S to put the 3D cursor in the middle of the loop, then set the pivot to the 3D cursor. - Scale, Z-axis only, type ‘0’.

The only problem is that, for lack of a better way to describe it, it looks ‘weird’. I’ve attached a screenshot of what the top of the shape looks like. It’s visibly not as smooth as the rest. I’ve also attached a .blend so you can see for yourself.

I’ve also tried some other ways of getting the same result:

  • selecting all the vertices above where I want the flat top to be, then deleting them, selecting the new ‘top’ of the shape and then hitting F to make a new face.
  • boolean difference with a cube.

Still get wrinkling. I also thought I might need more polys, so I selected the entire sphere and subdivided. Didn’t help, and it started to wrinkle the entire sphere if I subdivided more than once.

Is there a better (or ‘right’) way to do this?

BONUS QUESTION: what if I want to have the top flat face at an angle?


X_ArmTest.blend (581 KB)

Smooth shading will give artifacts when you try an smooth a sharp angle. Add an Edge-Split modifier to get a sharp edge.

Subdividing can give a worse result than lower res mesh and a subdivision surface modifier. Adding a crease value (Shift+E) on an edge can control the sharpness of the edge

Yep, Edge Split fixed the problem. Now it’s nice and smooth. Thanks!

Anyone else is free to chime in on the bonus question - in 3DS Max I would have just used boolean difference but, well, I’m not 100% confident in the results. I’ve attached a .blend file - the top face of the shape is a lot less rounded than I’d like, and it sometimes looks off when I’m rotating around in Perspective View. But it doesn’t really show up well in screenshots. Maybe I’m just being paranoid?


X_ArmTest2.blend (555 KB)

You could also use the knife tool
K (knife), Z (to cut all the way through your model), drag the mouse and LMB to cut, Accept with Enter.
Delete the neccessary vertices, selet the top edge loop (Alt+LMB) and fill with F

Okay, that’s getting close. I pressed K, then Z, dragged a line across where I wanted it and got a line. Then I deleted all the vertices above that line, selected the top edge loop, filled in the face…

And I’m still getting weird artifacts around the top face. Here’s another screenshot of what I mean. This is after I followed up with another Edge Split modifier, btw.