I've been working on a shot where fire emits on a surface (surface emitter). The shot is pretty much complete, however there was a directorial change where instead of the fire ending at the same time, the emission needs to stop across the surface (ie, from left to right). My first though was to use emitters with negative density to cancel out the emission in parts of the surface, and this works to some degree, but it requires a lot of negative emitters and hand animation to prevent it from looking like a wipe. As a last resort I am going to use a garbage matte with a rough edge to kill it (in addition to the negative emitters), but it occured to me that it would be sweet if maya provided a way to do this inherently. What would be perfect would be to have a plug into density emission, heat emission etc which could take a texture and drive the emission based on that (per uv on a surface emitter). I also tried various things like putting a lattice on the emitter and crumpling it, trimming the emission surface etc.
anybody have any ideas ?