Now my problem is:
how can i do in blender a cube with only an edge rounded?
if i understand correctly, you want to use something like set smooth but so it effects only one edge? select the edge or nabouring faces, then hit set smooth, it will only affect those edges.
but i need a bit more detail.
I tried to replicate that object you have, but the best I could do was take a cube, and a cylinder. Subdivide the cube once, hack off the vertices I didn’t want, and join the two objects together, and remove doubles where the two different objects come together. Oh, subdivided the curved section afterward to get the line down the center.
Do a set smooth to the rounded vertices of the quarter cylinder, and render.
There probably is a better way.
This is basically DracoFodder’s method, but with step by step (fairly newbie friendly) instructions.
In top view, delete the default cube & create a plane.
Immediately create a 32 vertice circle.
Press (S) to scale & immediately type .7071 (Enter).
Press (B) twice for the circle select tool & de-select the top right quad of the circle vertices (9 of them) by using the middle mouse button.
Right click or (ESC) to cancle the select tool. Shift+right click the top right vertice of the plane. Press (x) & delete the selected vertices.
Select the top left vertice of the plane & the left-most vertice of the semi-circle. Press (F) to connect the vertices. Press (A) to clear selected vertices. Connect the bottom right vertice of the plane to the bottom-most vertice of the semi-circle.
Press (A) twice (first to de-select, again to select all) & press Shift+F to fill.
Switch to front view. Press (E) to extrude the region & left click to set desired height.
Rotate the view so you can see the faces of the curved edge. Ctrl-Tab to switch to Face Select Mode. Select the entire curved edge. Press Set Smooth in the Link & Materials panel.
Possibly a slightly easier (but probably not) way would be to use curves.
You can then press alt+C to convert it to a mesh.
So, thanks to all, i’m impressed by the variety of solution that you can give to resolve the problem!
I have made one small search in internet to see how the other program resolve the problem.
Well… they do not resolve it at all !!!
3DStudio Max, Maya ando so on… failed the test.
Only Cinema4D have a special function, the others resolve the problem round turning with some trikcs!!!
I hope that in future the Blender foundation gives a commando to us in order to define the beams in a preciser and less difficult way.
You can get similar results by using booleans: http://mediawiki.blender.org/index.php/Manual/PartII/Booleans
actually most progams you would do a recursive edge bevel. You could do so with blender also but it wouldn’t be easy to attaing good results, so it isn’t recommended.
Another method would be to do a boolean of a quarter of a cylinder with a cube.