Can I affect the color of a particle as I rotate around it, causing it to be specific colors at certain angles?
Yeah that would be a really cool effect, kind of like the fish in Nemo when they rotate away from the camera reflecting more ligt. I’m not sure why that crossed my mind.
Anyway, there’s not a native way to do this in Unity. However, if you download the standard shaders from here:
http://unity3d.com/unity/download/archive/
You can edit the Default-Particle material’s shaders (See the Particle XYZ shaders under DefaultResourcesExtra). I think shader-wise, it should be straight forward. You have access to the matrices that define the view projection. You may have to bring in the camera position to the shader and compute the vector from camera to particle. I think you would also have to set the particle emitter Renderer to use Mesh instead of billboards. If billboarded, the particle will always be facing the player. But you could modify the color based on distance and angle off the line of sight.