Im trying to get 2 separate sets of particles running alongside each other and interacting correctly in 3D space. Im creating a flowing ribbon effect using streaklets, but wanted a second, different coloured ribbon to be moving around it and wrapping in front and behind it. Ive tried putting 2 instances of the effect onto one layer, but they do not interact with each other (they simply but one effect either entirely in front or entirely behind the other, depending on the stack order of the effects). Is there any way to have them know the 3D location of each other across 2 instances of the effect, or am I going into a dead end trying to do this?
unless particular 2.0 is different from 1.5 (the version i have), you'll need to get both 'emitters' into a single emitter or try aharon's method for each emitter (probably on separate layers) that he outlines here:
to try and get 2 emitters on one layer emitter, you would use a 3d layer as and emitter (choose 'layer' for emitter type and pick the layer from the list)... you'd be able to animate the x-y positions of the 2 'emitters' independently, but their z positions would be the same (since they are on the same layer), so i'm not sure that this would work for your animation...
if you wanted a simple test of how this could work, try this:
create a new comp (to keep it fast try a sd preset) and add a new comp sized solid.
add the circle effect, set the radius to something small (5-10 pixels), add an expression for 'center' and type wiggle(.5,200).
duplicate the circle effect (on the same layer) and choose a different color and set the blending mode to 'normal'... you should have 2 circles 'wiggling' around in the comp.
bring that comp into a new comp, make it 3d, rotate it on its x-axis to 270 (or -90) and animate its z-rotation 360 degrees and its z-position to move up the screen over 5-10 seconds. then hide that layer.
add a new layer and add particular to it. set the emitter type to 'layer', choose the hidden layer as the emitter layer, set the layer sampling to 'particle birth time' and set velocity and velocity from motion to 0. set the particles/sec to something high (maybe 100000 if you are using a sphere) and you might also increase the particle life to the comp/animation length.
you can ram preview to see how the two emitters interact. if they don't overlap enough, add a comp camera and use the orbit tool to orbit the camera around the particle system to see how they behave in 3d space.