In this video I show how make particles form on a surface and slide along the surface. I demonstrate how to write a fit01 function to create a gradient color over the entire length of a bounding box axis. This color gradient is then used as a falloff for secondary animation. There is also a brief introduction to CHOPs which shows how you can take a simple four keyframe animation and add after motion to it by using the Jiggle node to create a more organic feel. I use an animated Bend node to cause the source geometry to throw particles resting on the surface out into world.
You can download the finished HIP file with the mushroom object at this link.
You can see the final version of this animated mushroom in the Music Video Real Magic.