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[kraid]

Most of the time even hard surface models look better when there's a little smoothness arround the corners.

One way would be to add extra geometry and simply chamfer the prop.
The problem with that: if you need really round and smooth corners you'd have to add at least 3 subdivisions to that chamfer and increasing your poly- and vertics-count a lot.

Another method is baking a normalmap from a highpoly object with smoothed edges.
This one is used a lot and (if it's done right) the results are good enought to give the impression of smooth edges.

Today i'd like to show you another method i recently discovered.
It doesn't require a highpoly model and the vertex count isn't higher then with baked normals.

To get an idea of the effect we'd like to achive, here's an image of the test props i made.



As you can see, there's a simple chamfer with one literation, but since everything is in one smoothing group the vertics count is the same as it would be on a model set up correctly for normal baking from a highpoly object.
Plus you don't need to split your UV islands and do not need a margin between them, which possibly saves up a lot of UV space on certain models. Only the polycount was increased, but who cares about this these days?   

The next image is a comparision of a normalmapped cube, a cube without edited vertex normals and 2 cubes with edited normals.



As you can see, the normalmapped cube is looking ok for the most parts but it'll create a dark edge at some angles, too. The vertex normal edited cube won't have this issue.

In the next image you'll see an editor shot with wireframe enabled.
Look at the yellow lines to see how the vertex normals were edited to achive certain effects.



And here's a schematic view of it.




Depending on the 3D app you're using there are scripts or even plugins for easily editing the vertex normals.
Just some i found within a few minutes on google:

3dsMax: http://wiki.polycount.com/VertexNormal

Maya: http://migugi.net/mel/normalTools/

XSI: http://www.xsibase.com/netview_forum/index.php?board=16;action=display;threadid=32431

and last but not least my 3D app:

Cinema 4D: http://frostsoft.blogspot.de/p/plugins.html


Oh... and i just found another tutorial about this topic:

http://frostsoft.blogspot.de/2012/01/shading-interpolation-vertex-normals.html#more

Note that this is only one field of application for edited vertex normals, there are also many others e.g. making the leaf planes of a tree model appear less plain.

Since Source supports custom vertex normals (unlike UDK previouse to march 2012 build) we should use this method whenever it makes sense.

Eventually you can even avoid creating a highpoly model in some cases, which also saves up your time.

[CaptainCrazy]

Or you could just use a plugin called Quad-Chamfer xD