vgMask not implement?

[GG-coder889]

how to implement this function?

[Gorggg]

I would think this could be implemented someday by having a texture containing alpha values that are multiplied with the source. This is at least how AmanithVG seems to implement it, although I can't be sure because it is closed-source. Implementing it this way would also have the effect of making ShivaVG require 2 texture units, but for most modern hardware that shouldn't be an issue.