There are a couple of different ways to render trails generated by X-Particles with Arnold, but the easiest way is by simply adding an Arnold Tag to the xpTrail Generator. By using an Arnold Tag, you get a good bit of creative control without having to deal with lots of complicated settings.
I’m going to assume you already know how to generate particles and trails with X-Particles as well as have a basic understanding of using Cinema 4D tags and Arnold materials. Here’s how I do it:
As this is a frequently asked question we have provided both the question and answer in this thread.
Is it possible to randomize the color of each trail using X-Particles parameters? I've tried a bunch of stuff similar to you're demonstration here: https://answers.arnoldrenderer.com/questions/112/how-do-i-randomize-and-take-control-of-particle-co.... but haven't had any luck.
Is it possible to randomize the color of each trail using X-Particles parameters? I've tried a bunch of stuff similar to you're demonstration here: https://answers.arnoldrenderer.com/questions/112/how-do-i-randomize-and-take-control-of-particle-co.... but haven't had any luck.
@Dade Orgeron I am also trying to find a way to randomize trail-colours with an arnold shader. Any solution for that at hand?
Sorry for the late answer. To randomize trail colours you can use the utility shader with uniform ID mode. Or enable Export IDs on the Arnold tag and read the ids via a user_data_int shader. The parameter name is curve_id. You can connect it to a random shader for instance.