CompuServe Messages

Hi Dorian, Glad that the un-shadowed images are rendering well…thank goodness for small blessings, huh? 😉 First: the MacroModel shadowlight shaders (.slo) do lie in the "Shaders & Textures" folder in the System Folder, yes? (The .sl files are text files we can open, tweak, and recompile into new .slo's — it's immaterial where they lie.) The idea behind RenderMan shadows is the use of "shadow maps" — bitmap images rendered from the point of view of each light source, that show greyscale as a function of distance from the light…objects that are close to the lightsource are lighter in shade, objects further away are darker. We have to first render out these shadowmaps. The camera-view rendering then uses these shadowmaps in its lightsource calculations. The error message we're seeing is because there is not yet a shadowmap rendered and availble for each lightsource. The trick: if "shadows" is turned on in MacroModel, and "Export RIB" is chosen, then we will, as you note, have three RIB files produced. If the ".lt0" and ".lt1" files are rendered first, they will produce shadowmaps in the same folder, which the main (camera) rendering can then reference. If, on the other hand, the camera view is rendered before rendering the light views, then we'll see an error message that the textures (shadowmaps) for the scene are not available…that's what's happening here. Optimizations: ** If you're doing multiple test renderings, it's not necessary to re-render the shadow files! Assuming the lights and objects have not moved, we can then reuse the existing shadowmaps by just rendering the camera view. Very handy for adjusting light intensity, shading factors, etc. ** MacroModel gives very fast previews of where RenderMan shadows will fall! They work quite well together. ** We're not limited to the lightsource presets provided in MacroModel…opening up the RIB in a text editor allows us to specify different shaders. If you have the .slo files for all your lightsource shaders, then shader parameters can be read directly. Otherwise, use of something like the Valis Group's "Shader Detective" or Macromedia Three-D can reveal what types of light parameters are available. Hope this helps, John Dowdell Macromedia Tech Support