What\'s the usual way to round the edges on a cube, a rectangular object as in the examples?
Using deferred shading you may access G-buffer to locate and round edges like it done in this paper. Though it is a post-processing technique so it is able to emulate roundness in a limits of some pixels.
Simple averaged normals (1 pixel width):
Simple averaged normals (2 pixel width):
Simple averaged normals (3 pixel width):
We were able to accomplish beveled cubes for our game WorldToBuild. The key is really that you can go ahead and make the beveled model, then just move the vertices in groups.
So in short, all I had to do to achieve the effect was:
I wrote an article about it here. Scroll to the bottom of the article if you just want to know the process:
https://www.linkedin.com/pulse/coding-resizable-beveled-cubes-unity-richard-christley
I'd certainly defer to a shader-oriented answer, but especially if the necessary shaders aren't available on a given platform, I'd accomplish this with a few "level of detail" models aka LoD.
Give the GameObject a behavior script that checks each frame for distance from camera.
Activate the appropriate mesh based on the distance, and deactivate the others, this should be done at a distance where the change isn't detectable at the highest resolution available to the player.
This technique is pretty widely used in 3d games, a good way to represent far-off swarms of things that can become much more detailed once the camera gets up close.