For the intro screen, I am thinking to add a distance sensor to our booth. The sensor 

reading can be sent to p5 to show texts such as "Do you want to know your future?" and "drop a coin to start".

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When people approach this booth, the opacity of the text "Do you want to know your future" will increase. When it reaches the maximum, it will trigger the next text "drop a coin to start", we assume at this point, viewers will stop keep approaching the booth, drop the coin and stand where they are right now. 

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Today, I tested the ultrasonic sensor and its connection to p5 (link to p5 sketch). Basically, it can work. However, the reading from the distance sensor is not stable. We probably need to make sure the surroundings are cleared out when testing.