Background: I'm building an app that uses the camera to overlay objects (helmets, glasses, etc) over people's faces. I'm building a simple algorithm that checks if people are wearing glasses. Depending on the number of people wearing glasses, a custom hat is unlocked.
Requirement: Using this logic, I basically want to ask the user (in the settings section of the app) to specify the minimum amount of people that should wear glasses to trigger the custom hat. The lowest possible option is 1.
Problem / Dilemma: What's the best way of presenting this logic to the user, and collecting their input? I want it to be fun and very user-friendly, and realized that by using whole numbers (0,1,2,4), it would require the user to constantly go into the settings and change the number everytime they take pictures with a different number of people. Because of this I thought of using percentages or ratios, but I want the app to be as simple as possible (Don't want to scare anyone away with the math). I was thinking of using a Circular Slider that would allow the user to select anwhere from 25%-100%, and have their choice snap to either 25, 50, 75, or 100%. The problem with this is that I'm not sure circular sliders would be useful especially because in this case the user would only have 4 choices to select from, and anything lower than 25% isn't even a choice. What's a creative way of presenting this without using textfields, horizontal sliders, or buttons?