Ignore file types except within a specific folder (and all sub folders)?

Question

I'm trying to configure a .gitignore file such that all files with a certain extension are ignored, except where they appear within a specific folder, or any sub folder of that folder. I've tried the following which does not work:

*.lib
!Libraries/

A second question I have is, do negated exclusions only apply to the immediately preceding rule, or do every rule you've defined up to that point?-

This almost answers my question, but doesn't help for sub folders.

Answer 1

I think what you meant is ignore all *.lib except when they're inside /Libraries, try this out:

# The root directory's .gitignore
*.lib
!/Libraries/*.lib

# The .gitignore under /Libraries directory
!*.lib

The .gitignore is parsed from top to bottom. Any rule can override prior rules.