I’m trying to create a glass-clear plastic like object, that looks like someone has gotten blue paint and smeared a blue smiley face on it. Of course, The blue paint is fully opaque. The blue paint effect is going to be made in substance painter.
Just as Joseph said, it’s a Mix node…
First create you Smiley, in Texture Paint W/B image to act as a Mask…once you have that then that will be your FACTOR of your Mix node that combines your Paint Over the Glass…Something Like this…