I want to create an emitter that emits a single particle with a "life" that is the length of the comp. The single particle will be used as an overlay for another emitter to increase the other emitter's source-point "intensity". The single particle must be animatable by position so that it can move with the other emitter.
I'm posting my solution, but I would like some advice on whether or not there is an easier method. I tend to be a "brute force" animator who is always in search of a more elegant solution:
1. Set the particle type, opacity and color as desired.
2. Set the emitter to emit at the frame rate of the comp (say, 30 fps).
3. Set the particle life to the inverse of the comp's frame rate (say, 1/30th of a second)
4. In the Options dialog, set Pre-Run to 100%
This method works in this specific case, but I'm afraid I'm making this harder than it has to be.