Sorry I havent answered sooner, but Ive been off-forum this weekend.

Im afraid Im too noob at particles to even get your code to produce a beam,
(I think my test-level scales are too different).
But I CAN see where I think the one-beam-limit is coming from.

In your particle functions effect_normal and fade_normal you are calling
on global vectors emit_dst_pos, emit_src_pos, and emit_color.
I think that that because emit_dst_pos, emit_src_pos are globals,
when you create a second beam, these globals "drag" any existing beams
to the same orientation(ie underneath/inside).

I dont have a fix, and I know what you mean about not being able to pass
"customising" parameters through the effect function. I would like to
be able to too. But no luck so far.


Hope this is of help in finding a work-around. Sorry I couldnt help more.