Code for Processing

import processing.serial.*;

Serial myPort;

int r;

void setup() { size(600, 600); // window size

randomSeed(second()); // initialize random number

r = width;

println(Serial.list());

myPort = new Serial(this, Serial.list()[2], 9600);

myPort.bufferUntil('\n'); // store data in buffer

}

void draw() { background(255);

fill(random(0,255), random(0,255), random(0,255)); // fill with random color

ellipse(width/2, height/2, r, r); // draw a circle

line(width/2, 0, width/2, height); // draw a line

line(0, height/2, width, height/2); // draw a line

fill(0, 120); // black, transparency 120

textAlign(CENTER, CENTER);

textSize(r/2);

text(r, width/2, height/2); // express distance in the window (스케치 실행창에 거리측정값 표현)

}

void serialEvent(Serial p) { // Read Serial port value

String response = p.readStringUntil('\n').trim(); // Read Stored Data

r = int(response);

r = constrain(r, 5, width) ; // r is MIN: 5 ~ MAX: width

}