Simple Mapping by Object
Video below is made with standard planar mapping:
Advanced Data Manipulation | #Box3
Blending two predefined colors by checking if particles are inside proxy object (Sphere002). If the condition is positive, then that particle get one color value to the vertex color channel. If not, another color input value goes through the flow without any interpolation.
Also, keep in mind that suboperator New In Event is designed to take the initial value on the event entry only. It should be connected with flow output or proxy geometry input.
Above method isn’t recommended while colors are generated inside the flow. It’s always better to have colors in a map and in particles to set required mapping:
Same can be done with particles from another system:
Mapping by Age
Here is an example how to set mapping by Particle Age. Just Divide Particle Age with a Lifespan, but don’t forget that Lifespan channel requires data particles dying time, so Delete operator should be added to the particle flow. Alternatively, Lifespan value can be set in a data flow.
P.S. this is what can be done with applied Frost to the particles, just apply vertex color as a diffuse map to the frost material.