I am looking for a way to fade strokes over time to 0% alpha channel. The effect I want it for the strokes to slowly fade away while new strokes are being drawn on top, frame by frame. I also want to be able to layer the result later, so I need an active alpha channel.
I have tried several things using image operations and alpha overlays, but I'm not getting what I want. I can get the effect I am looking for if an alpha channel is not involved and I am drawing over everything. I have attached a sample.
Is this something that Time Particles can accomplish? and how? or is there some other way?
So, an easy way to create a fade over time to a static colored background is to use something like the Fixed Color image operation effect, with a Mix setting less than 100%. So if you ran Fixed Color to white with a 30% Mix as your first action step in a PASeq that is overdrawing, then the previous pained strokes would fade to white over the course of a few frames.
You can also process just the alpha channel using an ip op effect (as opposed to the normal rgb processing). You just have to set the IP Source to Current Layer Alpha and the Composite to Replace Alpha. Then the ip op effect will sue the current layer's alpha channel as input and output the effect to the current layer's alpha channel.
So, you can use the Fixed Color ip op effect like i described to fade the alpha channel. Since full alpha on is white and full alpha off is black, you want to fade to black, so you want the Fixed Color set to Black.