Texture masking

Graphics Shaders & Materials
1

Hello everyone,

I would like to ask for help regarding the matter of masking textures with below a example.
On the left is the way it currently is functioning(no masking), on the right is the desired behavior.

Thank you for any assistance someone might offer,

Willem

2

It looks like an alpha issue. I am not that good with 2D or 2.5D in this case.