Snapping not aligning to grid

[Nydelith]

While working with our “lego blocks” on this lesson, I’m trying to duplicate several pieces at a time (Alt+D) and rotate or mirror so that I can quickly create the rooms. However, if I duplicate MORE than one piece at a time, as soon as I move them they no longer align to the grid. I have snapping enabled, on Increment and “Absolute Grid Snap” enabled. Here’s a screen shot of the top-down orthographic view of what’s happening:

As you can see, they’re no longer in the grid squares. If I hold shift to try and manually correct it, I can’t seem to get it just right. If I duplicate only one piece at a time, this doesn’t happen and there’s no problem. Why is this happening when trying to duplicate multiple pieces at once? Both Alt+D and Shift+D do this.

[Capricas_Kirito]

What you are seeing is that the pivot point for your group has snapped to the grid. Remember, every transformation operation is done in relation to where the pivot point is set. Thus, if you want to copy groups of objects you will need to do matching sets (that is you will need to have matching geometry around the pivot) or switch the pivot to 3D cursor, Bounding Box, or possibly Individual Origins

[Nydelith]

I didn’t rotate or mirror the objects yet though. I merely duplicated them, and as soon as they moved from their original place, they fell out of alignment with the grid. I tried changing to Individual Origins thinking that may help, but it didn’t stop the problem from happening.

I think Michael mentions at the end of the lesson that he had the same problem and he’s going to cover it in a future lesson, and that it has to do with the objects’ points of origin. So perhaps I’m getting ahead of myself here. Thanks for the quick reply!

[Capricas_Kirito]

I’d like to call your attention to this area of the image you posted.

I’ve superimposed two lines over this that line up with the closest grid lines in the image. I’ve done this to highlight that the Pivot Point for your group is in fact lined up to the grid. Note that the Pivot point is always located where the transform tool is and when a group of objects (or parts of objects in edit mode) is selected the pivot point shows you the group’s collective origin, that is ‘the point mathematically calculated as the center of the group based on the average placement of individual origins within the group’. Since snapping is dependent on the origin of the Item, or group of items, being moved it follows that a group will snap in such a way as to put the group origin, or group pivot point, at the appropriate location. This is then why I suggested that you will need to switch your Pivot Point to either 3D Cursor or Bounding Box. with 3D Cursor you decide where the pivot point actually is based on where you place the 3D Cursor. on the other hand, using Bounding Box allows Blender to decide where the pivot point is based on the combined dimensions of your grouped objects, this includes space between them, rather than the average of where the origins are.