[bariumbitmap]

> Once you have a model, the problem you need to solve is how to make a model with no undercuts. Undercuts will make it impossible to remove the 3D printed positive

Is there a mathematical term for solids with this property? It reminds me of the vertical line test, but in 3D.

https://en.wikipedia.org/wiki/Vertical_line_test

[dreamcompiler]

I'd call it "monotonically expanding" along some particular direction vector.

[wgj]

In die casting, you have to do a little better than the vertical line test and stay within the specified draft angle. A vertical wall would be a 0 degree draft angle, and not suitable for casting most materials.

[dezork]

I would call it self-occluding.

[b_tterc_p]

Convex perhaps?

[FreeFull]

There are non-convex shapes that don't have undercuts. I think convexity implies that you don't have undercuts, though.