I need to create a ray of light coming from a projector (as in a cinema). There is a wonderful tutorial by Eran Stern that describes how to do it. However, I want my camera to move around in 3D space and thus I can't see how I can use the tutorial because it's made for a 2D project.
I've searched around and saw some tips about using Trapcode's Lux. I've taken a look at the plugin but the main problem is that the projection of the light is circular. Cinema projections use to be rectangular. :-) Of course, it is desirable that the rays reflect what's happening on the screen (as in Eran's tutorial) but it is not absolutely necessary. I can add some flicker later to simulate the effect.
The only way I can come up with is to create 4 semitransparent solids building a rectangular pyramid representing the light ray from the projector but I'm afraid there will be problems when the planes of the pyramid will overlap each other and reveal how the "light" is built.