I am not sure how to do this so I am hoping that someone can help. I have an object that is 1000 by 600 and I want to do a diagonal mask that reveals it from the upper left to the lower right with a shimmer as it goes down across the image. Does anyone know how to do this or have an example? I have been looking and cant seem to find one. Thanks in advance.
You probably need to make the mask that reveals it separate from the glimmer that follows the revelation.
Have a rectangle sufficiently large for the mask that is either skewed and run horizontally across the object or move it diagonal across the object from one corner to the other, ultimately covering it entirely to reveal it.
Create whatever you intend as a glimmer effect and have it track the leading edge of the mask on a layer above it.
What can't you figure out? Make a shape with a diagonal leading edge and then use that as a mask. For the shimmer you'll need another animated piece that matches speed with the mask. You could just do a white shape with blended edges at some low opacity...