Sorry for the late answer, but I didn’t notice your post before, since questions about BlenderMan are usually posted in the Python & Plugins forum (I only noticed it because of a search I made a couple of minutes ago).
Before going on to explain how to set up a shadow casting light, you have to be aware of several things. BlenderMan supports four light types: lamp, sun, spot and hemi (well, area lights are also supported with BMRT and Entropy, but the process of setting an area light with BlenderMan is completly different to setting one in Blender, so we’ll leave area lights alone this time). Of these four types hemis can’t cast shadows, lamps and suns can only cast raytraced shadows and spots support both raytracing and shadowmapping (have in mind that Aqsis doesn’t support raytracing, so you can only use spots for shadowcasting in Aqsis).
Now for a step-by-step explanation:
- Select a light, switch it’s type to Spot and turn on Buf. Shadow in the Shadow and Spot panel (This is a must! Even if you plan on using lamps or suns you first have to switch to spot, turn on Buf. Shadow and then switch back to lamp/sun. The Ray Shadow switch is ignored by BlenderMan.)
- In BlenderMan’s Object Editor click on Get Selected and depending on the renderer and lamp type there’ll be two buttons: Ren Shadow (shadowmapping) and Ray Shadow (raytracing). Click on the one you wish to use, if other settings appear (renderer dependant) set them up also and you’re good to go.
- To stop a light from casting shadow turn off Buf. Shadow.
Also have in mind that the Render panel controls (Ray, Shadow, Radio, etc.) have no effect at all on the BlenderMan export process.
Hope this helps.