Simple Bounding Box Code
The (ssget) function returns a selection set [which could potentially have multiple objects in it], but the (vlax-ename->vla-object) function requires an entity name [of a single entity]. You could just replace the (ssget) with (car (entsel)), or you could get more sophisticated about it.
EDIT: Also, what if you're in Paper Space when you run it? Do you want the result in Model space even then? You're already in the appropriate space if you're selecting an object to draw the box around, and you already have the opposite corner points [your minExt and maxExt variables], so I would just use a RECTANG command and give it those. I see no need for the last three variables that are set.
Further EDIT: Now I notice your reference to multiple object selection [wasn't paying close enough attention at first]. You would need to get the bounding box for every object in a selection set, and compare them to each other to find the overall extents of all of them. I have a routine to draw the bounding box around multiple objects, if you want to see how I did that comparison.
@kotropol wrote:
.... I wrote the following and I am getting the bad function error:
(command "rectangle" (car(minExt) (cadr(minExt) (caddr(minExt)) ((car(maxExt) (cadr(maxExt) (caddr(maxExt)) "")
You would need to wrap a (list) function around those sets of coordinates, and fix some parentheses problems. But you don't need those -- you already have the points as points in the minExt and maxExt variables. Just use those [and the correct command name]:
(command "_.rectang" "_non" minExt "_non" maxExt)
See my approach in the attached.
@komondormrex wrote:
and if the original set of lines to be rectangle is somewhat rotated?
The bounding box approach won't follow the rotation, but will be orthogonal to the furthest extent of the object(s) [dashed green here].
BUT you could at least get close with the SR command in SmallestRectangle.lsp, >here<. It checks at 1° intervals of rotation [though that increment could be reduced], so it may not land exactly on your source object's rotation. Look at other offerings in that same Topic.
as a matter of a sort of interest. and it is not a bounding box whatsoever but rather an apparent outlining rectangle or quadrangle formed by 2 vertices plines or lines...
