Ok, now for something a little more complicated...

To recap, there is a plane emitting particles downward toward the origin, where a sphere rests. This sphere attracts all nearby particles, and the particles that get close change color from blue to red.

My next goal is to make it so the surface of the sphere changes color as a particle nears it. I dont mean the entire sphere, I just mean a small localized region that is near the particle.

For example, I have a green sphere, and as a particle approaches it, I want the point on the surface of the sphere to glow orange gradually as the particle moves closer to the surface of the sphere.

Thanks all!