Rounded corners

[blackjak]

So I'm starting a tutorial non specific to any program, which I think will be a good way to learn how to do things in this one.

I need to make a 2D rectangle with rounded corners.

Obviously it's easy to draw a rectangle with poly lines but I'm not sure how to round the corners.

Can anyone point me?

[Stiglr]

Add equal numbers of additional vertices near each corner, then arrange these to create the curves you want at the corners. The vertices at the very corners will have to be "brought in", which you can do by simply selecting all four corner vertices and then resizing to a number like 95% or so. You can select parallel pairs of these, both horizontally and vertical and use the "align to axis" and drag them to position to preserve/restore symmetry.

Or, said another way, step by step.

1) Use the rectangle tool to draw a rectangle or square.
2) Enter Vertice mode.
3) Select Vertice > Insert Vertice two times. This will create three vertices between the corners on all sides of the rectangle.
4) Select and delete the center-most vertice on each side.
5) Still in vertice mode, select parallel vertices on the top/bottom and left/right sides of the rectangle and move them close to the corners, such that you will have three (or more) vertices that go around each corner.
6) Select each of the four corner vertices.
7) Enter 95 in the X and Y fields of the Scale tool at the left of the interface; Click the Scale button. This will move the corners in by an equal amount and create the rounded effect. Undo and try another number if you don't like the result visually. (If you choose to add a greater number of vertices around each corner, you may need to "scale" other pairs of vertices to get the result you want. The idea is to make changes in a symmetrical fashion, and not "eyeball" it.

[Hans_Petter]

It's a good thing to insert vertices multiple times without moving any of them. The shape of the model stays unchanged and the opposing side vertices are being placed exactly right, meaning that the top matches the bottom and the left matches the right. Sometimes I add a lot of vertices (but always an equal number of vertices for symmetry) until I get the ones I need. Then I delete all but the outermost ones.
This way I ensure that the ones I choose to use are perfectly aligned. For geometrical and symmetrical shapes it's always a good idea to avoid moving any vertex or surface manually by dragging it since 1) perfect symmetry will be lost and 2) it may inadvertently move the vertex along an unintended axis at the same time, especially in 3D view. However, if we set the positions by entering exact coordinates this can be avoided. I like the idea of "resizing" a symmetrical selection of vertices--I've never thought of that option

[blackjak]

Thanks, I'll give those ideas a go. I was thinking there might be a way to draw a bezier curve or some other way to draw an arc, but the vertex method will work.

[Stiglr]

Well.... you could draw a circle or elipse with many points to it, then remove all but what will be the corner points, and then create surfaces between the corner vertices to fill in the square/rectangle... but I'm not convinced that would be very efficient.

[Andy]

You could try this:

Make a cylinder (you need to use a cylinder for this since a disk will extrude differently) that has the radius of the corners you want. This one had 60 segments to make a nice curve.

Select half of it (the right-hand side here) and extrude, select the other half of it (bottom here) and extrude again.


Hold down the control-key when extrudng to keep it square.

If you need just the rectangle part, you can select the other surfaces and just keep a single 'side'. If you then want a single polygon, press 'c' to Surface->Combine all surfaces into one.

[blackjak]

Thanks Andy that turned out to be the easiest way

[tbd]

Andy's way is what I use as well, and you can also use it on a sphere if you need rounded cubes.