First post for me…but I’ve got plenty of other questions I’ll post later.
I’ve read a great deal of pages, watched many tutorials, and looked through the many posts in this category.
But I haven’t run across a means of doing the following:
I want to punch a cylindrical shape into a non-uniformly scaled sphere. I want the cylindrical cavity to be offset from the pole of the original UVsphere. I’ve tried a boolean difference, with the usual problems of the the ring where the spherical surface and the cylinder connect becoming ragged when I subsurf the sphere after doing the difference. This would be easy if I wanted the cylindrical cavity to be at the pole of the original UVsphere (just extrude the spherical cap, then flatten it). But I want the cavity to be offset from the pole.
I’ve even tried deleting faces and then rearranging the resulting hole to be circular. The edge of the hole, however, doesn’t maintain the shape of the spheroidal surface. Boolean difference approaches the result I’m looking for the closest, but the subsurf is poor.
I wondered if posting an image would be helpful. I’ve just never done it, so here goes…
(oh, easier than I thought…)
Here’s an example of what I’m trying to achieve, done with boolean difference. You can see the ragged edge between the cylinder and the spheroid. (Just to be clear, the cylinder is a cavity INTO the spheroidal surface. The lighting is off to the right.)
I’ve created this by:
Adding a UVsphere at the center
Scaling it into an ellipsoid (a factor of 3 in y, 4 in x, and 5 in z)
Then adding a cylinder (at x=2, y=6.3, z=-1) and scaling it by a factor of 0.4
Then boolean difference: sphere minus cylinder
I “set smooth” and subsurf.
Any method you can suggest would be greatly appreciated. Is there an angle limit I could use or some other means to guide the subsurf? (I’m very familiar with the math involved in meshes and such, just not how to apply it in Blender.)
Booleans are still hard to get clean from what I’ve seen. I can see a couple of possiblities.
If Boolean works ok at the poles, just do it there, and then
b) rotate the spheroid, then “deform” it however you want.
Take your spheroid, subdivide the area you need the depression to smooth it, select faces for the required opening size and extrude the region, but just push the faces in, not out.
Create a toroid instead of a mesh sphere, and convert to mesh, fix the “bottom” of your donut to turn it into a spheroid (and .
Use an Iso-sphere instead of a UV-sphere (optionally combine with any of above as well)
Oh, also, have you set Auto-Smooth and have you done Remove Duplicate vertices?
The cavity I show in the example is one of four I want to cut into the spheroid symmetrically about the end cap. If I were only doing one, pushing the cap into the end of the spheroid, rotating, and distorting would work just fine.
Your second idea “Take your spheroid, subdivide the area…” is interesting. But I’m not sure I understand how to do that. Subdividing the faces offset from the end cap will produce a non-circular region to be extruded. My goal was to produce a cylindrical cavity in the spheroidal mesh. Could you provide a description of the steps you would use in this method?
Your third idea “Create a toroid instead of a mesh sphere…” is also interesting, but I don’t understand this one either. A torus won’t have any set of vertices that outline a circular area (unlike the cap at the pole of a UVsphere). Could you provide a description of the steps you would use to go from torus to indented sphere?
I’ve searched for some way of using a knife to cut along a given path, but I’ve come up empty. I’d love to be able to create a sphere, create a cylinder (or other shape), then place vertices where the two meshes intersect. Something like a cookie-cutter effect, but simply creating new vertices rather than separating the mesh into two pieces. Know of anything like that?
(This came to mind while I was looking at the football for this year’s World Cup. Create a sphere, make a peanut-shaped tube and carve new vertices into the sphere with the peanut-shaped tube. Fast and easy. But I haven’t been able to find a way of using the knife tool that can do anything like that…)
That looks like it should do exactly what he wants - good one Warner.
Ah, the most of the other ideas wouldn’t work. The ISO-sphere is the single best thing you can do then.
Ok, just to be complete… Mind you, I’m not able to try this right now, it may be “non-optimal”.
select an area somewhat larger (experimentation required) than where the hole would be.
press w-key, select subdivide or subdivide multiple, or maybe even better smooth: now you’ve got lots more vertices
either select the edge of where the hole will be, or the edge plus a few and smooth several times - they will start to be more circular. Expand your selection to include more vertices around the hole and continue smoothing. You might try putting Propotional Edit on as well (o-key) to help smooth more gradually.
You can adjust the toroid control points at the opening, specifically, you would increase the size and/or altitude of inner (ie the donut hole) control points to get, um… “squarer” edges (closer to 90 degrees instead of smoothly rounded). After you converted it to a mesh, you’d have to manually create faces to fill in the bottom of the cylinder and the bottom of the toroid, now semi-sphere. But once again, if you’ve got more holes, forget it.
Remember, you can ALWAYS manually create a cloud of vertices and faces in any shape you want! If you have the patience.
Not positive about what you mean, but I’m assuming this is connected with the following as an example.
I gave up on Blender’s Booleans quite awhile ago, and haven’t used the new built-in or the Megabool script at all, but they’re supposed to be a lot better than the old ones. That said, I think the booleans will do what you want, but with extra stuff to delete. Try this:
create your object to cut, and also a nurbs object, for example a surface
adjust the nurbs/surface to intersect your object where desired then convert nurbs to mesh
boolean them
there should be a line/area of the intersected objects. if you click one of the converted nurbs mesh’s vertex, then press L-key, then delete, you should see the “cut-out” area quite easily.
Mind you, I’m not able to try this right now, it may be “non-optimal”.