Speed of mouse sets tempo.

*/

​

let bpm = 0;

let setBPM = 0;

let counter = 0;

​

let speeds = [];

​

function preload() {

 beat = loadSound('clock.mp3'); 

}

​

function setup() {

  createCanvas(800, 400);

  textAlign(CENTER, CENTER);

  frameRate(30);

}

​

function draw() {

  background(0);

  // Calculate speed of mouse in this frame

  let speed = dist(mouseX, mouseY, pmouseX, pmouseY);

  // Add speed to array of speeds

  speeds.push(speed);

  // Only keep 2 seconds of speed data around

  if(speeds.length > 60) speeds.shift();

  // Average speeds over 2 seconds

  let avgspeed = 0;

  for(let s = 0; s < speeds.length; s++) {

    avgspeed += speeds[s];

  }

  avgspeed /= speeds.length;

  // Scale bpm to avgspeed

  bpm = 5000*(avgspeed/width);

  // Only change bpm, every 30 beats

  // Reset beat counter to 0 when bpm changes

  let res = 30;

  if(abs(bpm - setBPM) > res) {

    setBPM = Math.round(bpm/res)*res;

    counter = 0;

  }

​

  counter++;

  // Play beat every 60/bpm seconds

  if(setBPM  > 0 && counter%int(30*60/setBPM) == 0) {

    background(255);

    beat.play();

  }

  // Display bpm speed is changing

  fill(255);

  textSize(48);

  text(int(bpm), width/2, height/2 - 50);

  // Display bpm actually affecting sound

  textSize(64);

  text(int(setBPM), width/2, height/2 + 50);

}