what murphy mentions is rather useful
A lightmap is like all ilumination and shadows baked into a tga(for example). That way, the engine does not calculate complex cpu heavy light calculations: it just overlays in somewhat multiply mode a B/w with greys bitmap that does the effect perfectly. The rendering of that tga is done in whatever the package. You bake then GI , rich lighting in your renderer, and export that mesh with it's UV mapping and a lightmap bitmap asigned to it. Softwares like Max or Gile[s] can do this internaly and output a double chanel mesh file (you need two uv channels: one for texture(s), one for lightmap(s)) .But besides few formats have this support (obj is great, but doesnt) , few tools do support this 2 uv channel thing. Blededr doesn't. But if for example you bake the lighting in blender into a tga -is possible- and export the OBJ with the tga asigned to its simple channel 1, as if it were a texture. And then export as another obj the same scene, just with its real texture asigned to again uv channel 1, well, you will have 2 objs, one with its UVs and texture, and another with it's lightmap (actually a tga or bmp, etc) and its UVs (can be the same, but often is useful do another)
What Murphy did was a tool called OBJ2MIM that took those 2 files and converted into an xml file , *.mim , where you could even edit the type of multiply mode to use for the lightmap...Was freaking useful.
I guess what he's suggesting now is you do add this support directly for the artist. he made for the testing a viewer, which was actually irrlicht 0.7, which I used to go back and force testing new changes to the lightmap and texture, etc, at speed of light. Was so fast that not much of a difference than if it were a full packge. Well, if all's done in a package, good, but actually was more direct: at the end, there's a need to export to real engine, so , I prefered to do the preview with the engine than rendering in the 3d tool viewport, often.
MY3d and other solutions are great. I worked so at companies, with similar plugins.
But the OBJ solution is uber flexible: close to all 3d packages can output an obj+uvmapping+texture. And is all required (and that tool can bake the lighting into uv, but there are a few able already)
Also, is a solution for the poor
