Curved EDGES in Blender

[Bitsy Buccaneer]

Hello helpful people,

I'm trying to sort of emboss a standing stone by extruding part of it. The thing is, I need curved edges. The picture below has Circles added from the Curves section of the Object menu to illustrate. Is there a way to add these curves as Edges to my main object? Join doesn't work because they're not meshes themselves. If not, any suggestions on how to other approaches? This is the only mesh detail so I can afford to make them very smooth - smoother than I can manage via a knife cut. I went looking for other tools but haven't come up with anything yet.

The curved edges needed are 8 quarter circle pieces, so two complete circles' worth. 

The only way I've thought of where beveling might work is to extrude the rectangular bits, bevel from some of the y axis edges created and then de-extrude what's not needed. I'd prefer to only have to extrude (plus or minus) once though, so there's no worry about getting things back to the correct level, which is why I'm hoping there's a way to add in the curved edges before extruding.

Thanks in advance.

[Dora Gustafson]

You may do it by intersecting your object with a cylinder:

use:

Mesh / Faces / Intersect

You will get all edges and vertexes where the cylinder intersect the box and you will need to do some cleaning up to keep only that.

:smileysurprised::smileyvery-happy:

[Drongle McMahon]

Hope I've understood the aim here. It's a pity the Profile paramter of Bevel won't go down to zero, as that would have made it very easy.

As it is, the easiest way (as Dora said) may be to use the Boolean modifier: Snap the cursor to a corner; go into object mode and add a cylinder; scale it to the required size; then reselect the other mesh and add the Boolean modifier using Difference and the cylinder; apply the modifier; repeat for each corner.

Another way is to use the Spin tool. Use Loop Cut & Slide to make a cut that will be where the circle meets the edge of the box; snap the cursor to the corner; look straight down on it; select the two vertices of the cut edge and use the Spin tool to extrude it 90 degrees (+/- as appropriate) with however many segments you want. When you have done all the corners, you can delete the original corner vertices and fill in the faces using edge loop bridging and/or F (exactly how depends on whether you like ngons or not). I had to recalculate normals too.

Maybe this will give you some ideas...

 In either case, you can use your picture as a background image, that will be visible whe looking directly along an axis in orthographic view mode, to guide you in getting the circlular edges in the right places.

[Drongle McMahon]

Here's another simple way...

Note that the added circle is a mesh circle, not a curve.

[Bitsy Buccaneer]

Thanks to both of you for your suggestions. I've used your second method, Drongle, because it was a great way of extending my skill set. Thanks for the clear instructions too. :-)

So now I've gotten stuck on the UV map again. Most of it I've been able to Project from View into a nicely ordered UV, Ctrl A'd into scale and everything. I'm stuck on the inner edges of the extruded cross though. I thought to try it in four sections, one for each quadrant, but there's no way to get a head on view of course.

Any suggestions?

[Aquila Kytori]

Ooops, seems like i'm a bit late with finishing this  but hopefully it will be useful for some future project..........

Another method you could have used.............

The Celtic cross is symmetrical abut two axis so is an ideal subject to use the Mirror modifier on.

A background reference image should be set up to be centered to the center of the 3D editor.

The mirror axis always passes through the objects Origin point and in Blender when you add a mesh primitive its origin will be where ever the 3D Cursor is located. So it it is important to have the 3D cursor at the center of the 3D view. Therefore start by doing that.

Shft + S Cursor to Center :

The Mirror modifier is so useful that if the above is too confusing then I urge you to check out video tutorials on using Blenders Mirror modifier and experiment with it .

[Drongle McMahon]

Aquila is absolutely right. Whichever way you do it, you should use the mirror modifier. I nearly always forget this and end up cursing myself for making myself repeat everything four times (or often more). In general, you will always save huge amounts of time by thinking about exploiting symmetry before starting. Linear repeats too - you can use the array modifier. This is even when the final repeats won't be perfect - you can apply the modifiers and edit in the differences at the end. Keep a copy with the modifiers unapplied too. This will also help with the UV mapping. Do that before applying the mirror or array modifiers, and finish off afterwards.

[Drongle McMahon]

I found I could UV map this quite nicely thus: look straight down on it; select just the flat faces and do U, project from view. Now select the four outer vertical corner edges of the base and one vertical outer corner edge on each arm of the cross. Mark these eight edges as seams. Mark the edges between the the sides of the cross and the sides of the base as seams too (if they aren't there, make them using J. Now look at it sideways on with face select on. Boundary select just the base vertical faces and do default unwrap (UU). Do the same after selecting just the vertical edges of the cross. Finally select everything and scale the three separately mapped parts of the UV map to the same scale. You can do that either using the Stretch Area disply, to get them all the same colour, or from what you know about the dimensions (or both). Finally move them around to maximise use of the area and allow a littl;e margin. Here is what I ended up with. Sorry, no step-by-step pictures this time. I need sleep.

[Bitsy Buccaneer]

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Drongle McMahon wrote:

Sorry, no step-by-step pictures this time. I need sleep.

 

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Grins.  Then I won't have to name my first child after you after all? ;-)  I'm impressed by how much time the regulars here, but especially you and aquila with your multiple screen shots, have put into helping me and loads of others. Thank you most sincerely.

I think I have something fairly reasonable now. Just need to clear my head enough to switch into GIMP mode for the texturing. I got really peeved the other day when I couldn't mouse scroll to resize. :-)