Clockwise rotating fade animation?

[SuperbowserX]

I'm making a visual novel that pays homage to an old game I love (Cause of Death), and in trying to recreate it's style, I want to recreate the way it handled timed choices. I'm looking for the transforms that can help handle a clockwise animation.

Think of a clock with one big hand. Right now, the clock is pointing at 12, and the whole clock is white. Over the course of 5 seconds, the big hand rotates around the clock clockwise, and any area the clock hand passes is now grey. After a quarter of the time, the upper-right corner is grey. Half the time, the right half is. At the end of it, the whole clock is gray.

For a sample of what I mean, see this: https://i.imgur.com/KgkF04e.gifv Note the clock at the bottom. It is doing exactly what I want to recreate; the top image (the white) is fading away in a clockwise manner, revealing the image at the bottom.

I have an image of the grey circle and I can easily make a same-sized one of the white circle. What transformations would I use to make it so that the image on top (the white one) fades itself away as it rotates clockwise, gradually revealing the bottom image (the grey circle)? I'm familiar with linear and screen actions but I'm not sure how to make it so that an image fades away in a clockwise direction.

[Imperf3kt]

I'd fade the gray circle in with a wipe, myself.

[philat]

You could try an imagedissolve. https://www.renpy.org/doc/html/transiti ... geDissolve