What Roger needs is the ability to merge points based on a threshold distance, an ability currently missing from Blender's bag of tricks. That is to say, instead of all this talk of first group, second group, etc, the same effect can be achieved by grabbing all the points involved in the merge process and then have Blender merge points which are within certain distance from each other.<div>
<br></div><div>So, if you want to merge two walls, you bring the two edges where the walls meet close enough then tell them to merge if points are closer then say 0.1 blender unit. If points making up the edges of one wall are separated by more then 0.1 blender unit but some corresponding point on the other wall is closer then 0.1 blender units then the two wall edges will be merged.</div>
<div><br></div><div>The problem with this approach is of course that the end position of the merged points are the average of the two or more merged points and not this or that group of points. In the case of a wall with straight edges this is simple enough to fix. Just grab the newly merged points and scale it to zero in what ever axis it needs to be. For more complex shapes it might be interesting to have the ability to denote which group of points get to retain their value while others get moved. However, this is a luxury item I've never looked for myself.</div>
<div><br></div><div>phong.</div>