Newbie question, components and surfaces



I’ve actually been using SketchUp for a while but only in a limited manner, and I continue having a problem with components and their surfaces. Referring to the image:

  • The green, blue, and red boxes represent straw bales.
  • The gray objects the blue bales are resting on represent plywood boards.
  • The lighter gray object the green bales are resting on represents a floor. Think of linoleum. I think it’s 3/16" thick as drawn in SketchUp.

These are all components. The problem is that, while the tool seems to respect the components’ surfaces, and sticks them together properly most of the time, it’s easy to move an object such that it encroaches into the object it’s supposed to stick to. See for example the closest blue bale in the image, which has been placed such that part of it shares the same space with part of the plywood board (i.e. it seems to have stuck itself to the wrong side of the other component). This causes me all kinds of problems.

Is there some way to prevent this, for example by setting a property on the components that tells SketchUp that they’re solid and not to let them move into each others’ volumes?



That’s an inference system issue… where SU recognizes and acknowledges that there are two edges next to one another…and it’s going to offer you the choice to snap to either one.

And I know you want the top side to be more heavily weighted in the snaps decision making here.

But I don’t think we are there just yet.

I think you’ll have to develop more sensitivity to how you approach competing snap points… and maybe if you’re not already doing it… refine some technique on how to lock inference directions via the Shift + Arrow keys.

The direction of approach can make a big difference too.

By Dropping in from the top, SU should be recognizing that top surface slightly before it starts tracking on the lower one.

That slim margin of lag time is the sensitivity I’m referring to.

There’s a delicate balance to be found between your normal modeling (e.g. drawing) speed, and the zoom distance you have in place.

Everyone has to learn to internalize this, before mastering the inference system… which typically is quite good most of the time.

Some nice comments can be seen in the following by @Geo, and others:


You’ve lost me on some of the terminology here, but “Margin of lag time” seems to make sense because this seems to mainly happen with thin objects (like those plywood boards, and the floor object).

For my particular application, the thickness of the boards and floor does not matter - if I could make them infinitely thin (i.e. practically two-dimensional) that would probably solve my problem. But I don’t think I can do that either.


Yes, and it’s all about constraining movements only to two axis, preventing them from moving up and down when you shift things around. If you aren’t already moving objects locked along the red and green axis using the arrow keys, now is the time to start. Combined with moving objects strictly from their edges and corners and making use of the built in inferencing, you’ll soon master avoiding collisions.

If you’re talking about a built in collision detection and prevention, I’ve never heard of one but it could be out there.


There are extensions that provide physics simulation but they’re not really necessary for this.

@mnshaw I would also suggest zooming further inwards especially when you have a fairly thin panel to move the object to. The top and bottom faces are very close, it’s all too easy to get the wrong one.


You can set the components to ‘Glue to’ which will make them stick to the face you choose.


Thanks for all of the suggestions, everybody. You’ve given me a lot to work with!

In case anyone’s curious, my particular application is designing Barn Hunt course maps.


MSPhysics can create collisions. You’ll love it.