Format
filter(type=“alpha”, …)
Args
x: Horizontal offset of mask (defaults to 0)
Uses an icon or render target as a mask over this image. Every pixel that is transparent in either the image or the mask, is transparent in the result.
The x and y values can move the mask from its normal position. By default, the mask is centered over the center of the image.
The MASK_INVERSE flag will invert the alpha mask so that opaque areas in the mask become transparent, and vice-versa. There is also a MASK_SWAP flag which treats the source image as the mask and vice-versa, which might be useful for some effects.
Note
Unlike many other filters, this filter is taken into account for mouse-hit purposes.