How can I make a beveled edge with bump mapping?

Question

I say bump mapping for lack of a better term, but that may not be what I need. I'm trying to make my corners of various objects look bevelled as opposed to square:

I can't just create a physical bevel on all the edges (performance concerns), and I can't just apply soft shading (I want a hard, but beveled, edge), so I'm trying to figure out if there's a way with shaders / bump mapping to apply a beveled / tapered look to sharp edges to give them a bit of a blunt feel, or even appear to actually be tapered sharply rather than just blunt, but either way is fine.

How can I make an edge tapered / blunt with bump mapping / shaders?

Answer 1

The usual approach to this is to use your 3D software to create a “high” and “low”-detail version of your model, then bake a normal map that maps the details from the former onto the latter. For a simple example, take a look at this high-detail and low-detail version of a beveled square:

…followed by the baked normal map, and the low-detail square with the normal map applied to it:

Silhouettes will be visibly wrong at mesh corners, of course, since the low-detail version of the mesh doesn’t have the additional geometry there, but on continuous edges that don’t protrude from the object the result can be very convincing. As a bonus, thanks to texture filtering (sampling the normal map at locations “in between” its pixels), you’ll get some slight additional rounding at the edges of your bevels—note the highlight just below the top edge in the image above.

The exact process for this differs between 3D packages; in Cinema 4D you use a “Bake Texture” tag on the low-detail object, turn on Normals, and drop the high-detail object into the Source field, but in general you can search for “[name of 3D software] bake normals” and probably turn up the workflow for what you’re using.