A lot of pets will ignore you, but only a cat will follow you from room to room and check your lines of vision to make absolutely certain that you can see them ignoring you.
fun fact: cats actually have very good peripheral vision and do a lot of checking things out with it. full-frontal staring into your face is, for them, an aggressive statement. hence they do that a lot when they’re trying to make you do stuff, like feed them or play with them.
if a cat sits with you but at an angle and won’t meet your gaze, they’re not ignoring you at all! they’re hanging out. they’re having chill bro time.
if you want to smile at your cat, look at them till they see you, then give a slow blink. this is a cat smile. if a cat only glances at you to give you a blink and then looks away, that is a warm greeting, like, ‘hey there, buddy’. be polite right back at them and don’t seek out or hold sustained eye-contact in friendly, casual situations.