   Flashlight Beam + Shadows
  Hey guys,I'm tinkering around with Windows Phone 7 programming, and want to get a flashlight effect with obstructions in the beam causing a shadow. This isn't just a shadow on a wall, but a visible beam of light with objects causing sections of the beam to be "cut out". Because of the platform, I can't use custom shaders, however I can use the default shaders for stencil or depth masking. Any tips or ideas?Edit: This is a 3D game, so the beam would either be a cone, or a rectangular pyramid coming from a source.Edit2: Since I can't use custom shaders, I assumed this would qualify as non-API specific.   
  You want shadow volumes or the reverse "light volumes". Assuming you're dealing with low polygon objects it should run very fast to calculate the volumes.   ;  It's likely that 80% of my objects are boxes, so it will be dead simple to generate shadow volumes. I guess I'm a little unclear about the difference between light and shadow volumes. Are there any comparisons or examples of each? And do both volume techniques support multiple light sources?Edit: Now that I understand a bit more, won't I need both techniques to keep the back faces of any objects in the lights path unlit? Is there a way to do both light and shadow volumes in 2 passes together instead of 2 passes each?   