erasing with actionscript

[Kirl]

Is it possible to erase color with actionscript, so that a hitTest returns false?
Normally I'd overpaint with the bgcolor but this won't fool the hitTest function which I mean to use.

I've been thinking of using a mask, but I fear it's quite cpu heavy and I don't know of it'll play nicely with some of the filters I'm using; It's plan B for now.

Any suggestions for a plan A? :)

[gnomeontherun]

I don't know exactly, but could you describe what you want to remove the color from, and what the purpose is exactly?

[Kirl]

I'm trying a sort of multiple dissolving trails effect. I want to erase parts of lines drawn with the actionscript drawing API, but I need to have a transparant bg.

[gnomeontherun]

I don't know exactly, thats tough. The idea that I have come up with is that your mouse has to draw 100 little movieclips in the trail, and that each one has a different opacity from 100 to 1 so that it fades out, and hopefully it would be done in such a way that then you could remove the last movieclip and its smooth, otherwise plan B sounds better to me.

Maybe someone else has other ideas?