Masking + Animation with SVG's

Hello,

I am attempting to use a SVG as a mask in an animation, however I am unable to determine what the correct custom css code I need to use to enable this.

I understand how to use the overflow (hidden) property in the Sencha interface, but I wish to create a more complex mask animation with a SVG.

Below is an example image illustrating what I'm trying to accomplish. Is this possible within Sencha? Thanks for your time!

SVGMaskQuestion.png