Entities disappearing in some views

I have noticed an odd thing that happens with 2D entities sometimes. I often use 2D entities in a 3D drawings to show things like door swings. I find that they sometimes show up and sometimes don’t. It doesn’t seem to follow a set pattern as I have had floors at different levels where the problem only affected one floor.

In the simple drawing attached, for example, I have used 2D entities to show a door swing and a set of folding doors. In a parallel projection plan view, the entities are not necessarily visible. But orbit the view and they appear again.

Does anyone know what is causing this?
Patio 2016.skp (555.9 KB)

I’m unable to look at your model but as a guess I would say you have a 2d ‘elevation’ of a door and when you look at it from above in parallel projection all you will see is a line.

It happens at time for me too. I don’t know exactly why but for now just select the groups and move them up and down back and it should work !
Maybe it is a thing of z fighting.

No, Box. The entities are drawn in the XY plane as you would expect for something in plan. They have no thickness, being 2 D, so if you viewed them from a side, you are right, they would show up as a line.

The point here is that they do show up correctly some of the time but not always. I have another drawing with the same problem and have noticed that they can appear and disappear without warning and without any user input.

The problem may be related to the fact that these entities lie on a 2D plane (though are not part of it). In normal CAD practice, you would resolve this by adjusting the draw order.

It’s guess work until we see what you are working with.
Either attache the model here, if less than 3mb, or to the 3dwarehouse if larger.
Or at the very least a screen shot so we have something to go on.

Sorry forgot you had posted the model as Im only on a phone.

This appears to be a truly bizarre OpenGL glitch akin to “bleed through” (in which edges below a face can show through). The following will likely be too technical for most readers, but I present it so that maybe someone at Trimble can ponder the situation.

The top face of the floor in that room starts in the ComponentDefinition at z=110mm and gets placed at approximately z=0mm via the ComponentInstance Transformation. In other words, the z location in the model is calculated rather than exact, which makes it subject to computer arithmetic imprecision. The edges of the swing indicators start at z=0mm in the ComponentDefinition and also get placed via its Transformation, but because the Transformation is acting on a hard zero in the ComponentDefinition, the swing indicator gets placed at exactly z=0 in the model. That is, the Transformations produce in-model z values that are ever so slightly different, and evidently this is causing OpenGL to decide that it should not display the swing indicators in that specific view. The variances involved are way below what one should be expect to cause issues, and with even the tiniest of orbiting, the swing indicator’s edges become visible.

Edit: note the floor group is nested inside another group, which means its entities go through two stages of Transformation to be placed in the model.