Select the objects in Object mode. Ctrl+j should give you a pop-up asking “Join selected meshes?” Click OK, and they are now a single mesh. I think it works with more than two objects, but all the objects must be mesh objects. Pressing a key to select all may pick up objects like lamps and cameras, which can’t be joined to meshes.
Note: this won’t “connect” the vertices in one object to the verts in another object. You’ll have to do that separately by making faces between the unconnected edges of the (formerly) separate objects.
When you use Ctrl-J to join objects you need to have one of the objects in focus. If you have used box select or A to select the objects you will need to Shift select one of the objects to put it into focus before Join will work. The Object centre of the in focus object, will become the centre of the joined objects.
Recap:
Open your obj file. Select all the loose parts, and make sure one of them is the “active object”, how do you know this? because it should be outlined in a brighter shade of pink than the other objects(or in pink rather than magenta, I dunno). If you shift select each object separately, then the last object selected should be the active one. If you box select them all, chances are none of the selected objects is “active”, in which case you just shift+rightclick the object you want to be active, keeping in mind that the objects “center” will be now the center of all your model.
After this, press Ctrl+J. This joins all selected objects WITH the active object(that’s why you need one of the selected objects to be active). Still, faces that were adjacent, belonging to different objects, are still just “adjacent” and not welded together. That is to say, they don’t share any vertices. To fix that(if you want to), you must select all your vertices(pressing A once or twice is the fastest way to do it) and then press W to summon the “specials” menu and select “Remove Doubles”. This merges vertices sharing the same(or very close) space.
That should be it. If you get the hang of it, it shouldn’t take you more than a minute.
After the OBJis imported, all the meshes are selected so I am fairly certain that all my objects are meshes. I did see the message bout needing to have an object in focus so I shift clicked on one of the imported objects in the outliner to make it in focus.
Cosimo_0,
I tried your method and it did partialy work for two cubes, but the remove doubles seems very crude. It really needs another dialog box to popup with a tollerance. If my two cubes are not exactly in overlaping, it does not remove the doubles. So I guess it is a remove exact doubles. What I need is a join close neighbors or a true “weld” function.
Atom, try unselecting everything(“A” key) and selecting again, one by one.
About the dialog*, it actually is there. In the Buttons Window(the on below the 3D window on the default screen), on the mesh buttons(press F9 to see it), there’s a cluster of buttons under the tab “Mesh Tools”. Remove Doubles is in there (Rem Dou), and beside it an input field that goes from 0.000 to 1.000. If you increase that, you can “weld” not so perfectly aligned vertices.