This was posted by Discreet's Greg Niles to the combustion news forum:
< quote >
From: "Greg Niles"
Subject: TIP: How to make AE-style "Bevel Alpha" in combustion
Date: Tuesday, October 10, 2000 2:25 PM
A number of people have been requesting recently if we can make a "Bevel Alpha" plugin for combustion, similar to the one in After Effects. Well, the good news is - the included (and very flexible) Bump Map operator can already do this. Another poster recently hinted that this is the answer - so here's exactly how to get the "Bevel Alpha look" using the Bump Map operator:
1) Create or import a layer into a composite operator. If you import a layer, make sure it has an alpha channel.
2) Select the layer, and choose Stylize -> Bump Map.
3) In the Bump Map controls, click the Layer button, and choose the operator directly before the Bump Map operator as the source. For example, if you've imported footage, choose the footage operator as the source; if you've created a paint operator with some text on a layer, choose the paint operator as the source. Basically, you're feeding the layer into itself for the effect you want.
4) Choose "Alpha" in the Channel popup.
5) Set the Height. To approximate the default look of the AE filter, use a low value, perhaps between .25 and .5 (you'll have to type it in - the slider will show an integer percentage, but the value you set is still stored and used).
6) Set the Smoothness value, a value between 1.00 and 2.00 is a good start.
7) Set the Source Longitude to -60 degrees.
Of course, you can start tweaking the settings to get different looks - play with the Softness control to make sharper edges, or adjust the Ambient, Diffuse, Specular, and Shininess to control how the edge highlights and the
"face" of the bevel appear. You can also set a light source color inside the operator, which can be combined with combustion's regular 3D lights for some interesting looks.