Game mechanics/code question thread

[GaiusLukasCäsar]

What are the requirements for an AI to be willing to capitulate as my vassal as part of peace negotiations? I was Autocratic Poland and fought a war against Free Brazil who spread their ideology over the world thanks to their high tourism output. I wanted to force them to capitulate as my vassal so they would adopt my ideology and convert the world, but every time I wanted to negotiate peace, he only offered luxuries and gold but the option to capitulate was always greyed out. I already had the Ottomans as my vassal in this game who were fairly easily forced to surrender but I can't remember how exactly I did that.

 

[CrazyG]

What are the requirements for an AI to be willing to capitulate as my vassal as part of peace negotiations? I was Autocratic Poland and fought a war against Free Brazil who spread their ideology over the world thanks to their high tourism output. I wanted to force them to capitulate as my vassal so they would adopt my ideology and convert the world, but every time I wanted to negotiate peace, he only offered luxuries and gold but the option to capitulate was always greyed out. I already had the Ottomans as my vassal in this game who were fairly easily forced to surrender but I can't remember how exactly I did that.

Usually if you take their capital they will capitulate. Or multiple other cities