model falling part way through floor

I have a plane across a large area, and a few primitive boxes initially in the air. I also have a model imported (via FBX format, Y axis up, with meshes have colliders turned on). The floating boxes and the model have rigidbody attached, and using gravity. The plane just has a box collider attached.

When I play the scene the boxes behave completely correctly (well, maybe the very corners stick through a bit), even bouncing off the imported model if they are close enough, The imported model hits the floor (from a very low height), but instead of just settling there some of the model ends up below the level of the plane.

If I position the model higher in the air, it can even catch on the floor for a moment, before then passes completely through. If I make the model a lot larger (nearly as big as the entire plane), less of the model sticks through.

Is there a way to set the effective physics resolution of the plane, so that things can't fall through it?

Ok, after typing all that I thought of something to try, but I'll leave the above text in here so that someone doing a search might find my answer too. As you all probably knew, placing a cube automoatically includes a box collider, and the tutorial had me make a cube and not a plane when it came to the physics example. It turns out that a box collider on a plane does not work so well, and if you want a plane that acts as a good solid ground you should make a thinned out cube with its box collider instead. Then things behave correctly.

I wonder if from a physics point of view whether a plane should be thought of as infinity thick instead of infiinitely thin?

 

Good question. I think objects passing through each other has to be one of the most-often asked question on these forums.

 

Thanks for the pointers, I read up on those things. As for my model, it's about 1.3x1x.8 metres, so not tiny. I was going to keep looking, but as you've mentioned size, how do you make a particular sized primitive? Do you assume that the primitive is 1 metre in all dimensions, and then adjust the scale, but read the scale value as metres?

 

The scale is just a multiplier. So 1.5 meters scaled by 3 gives 4.5 meteres. And so on and so forth

d.

 

In other words, no, there isn't a set of Size fields!