Hey, I'm very new to this software, and am trying to learn it through videos and the Houdini handbook. I'm trying to make a simple animation of text disintegrating into floating particles. I've been following a video, but it doesn't go into too much detail about each node, so most of it I'm just playing around with. When I try and set the scatter density to Cd, I thought it was supposed to keep the points to only where the text changes colour (to a value of 1), text is originally black, and it turns to red as a sphere passes through it. It didn't work, and I got it to work by changing the starting frame in the Popnet node to 57 (when the sphere starts to grow over the text), but the particles are stuck at that point until frame 57, when the simulation starts. But when the sphere takes up all of it, the scatter points return to where the original text was even though it's not there. I'm not sure what I'm doing wrong, or what to do to kill it after the sphere growing is complete. Below are photos of what I've done.

Any help is appreciated!!