4-3

function setup() {

  createCanvas(windowWidth, windowHeight);

  background(100);

  x=width/2;

  y=height/2;

  delta = 10; //變化量

}

var x,y;

function draw() {

  delta = mouseX/50

  x+=random(-delta,delta);

  y+=random(-delta,delta);

  x= lerp(x,mouseX,0.05)

  y= lerp(y,mouseY,0.05)

  //lerp() 逼近 讓兩個數字盡量逼近

  var colorR = map(mouseX,0,width-10,0,255);//map 0到255

  // print(colorR);

  fill(colorR,0,0);

  ellipse(x, y, 100, 100);

}