Particles Change Color on Collision?

[RomanB]

 
@RomanB
I am not sure I understood all your questions (some reference images or video could help)... but it's really easy to scatter particles using texture.
Inside Position Object operator you have texture option, and you can instance any texture from material editor, and particles will be positioned on brightest spots of the texture (or opposite, if you want it like that)

Thanks for the response. I will add pictures with a more detailed explanation of the desired effect a little later.

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@ Chrissonator
Surface test is your friend.
Just use that operator and reference the object that will change particles (you have various options: Distance, volume inside, volume outside), and just send particles to next event with different color (or material).
If you have some forces (wind, speed.. etc), make sure you copy them to event 2 also, so particles keep moving when entering second event with changed color.

The collision operator would also work, I think.