function setup() {
  $('<h2>').text('line() サンプル ').appendTo($('body'))
  createCanvas(500, 500)
  noLoop()
  background(220)
}

function draw() {
 //line(30, 20, 85, 75);
 for (let x=0 ; x <= width ; x+=10) {
   //line(0,0,x,height)
   //line(width,0,x,height)
   //line(0,height,x,0)
   line(x,height,x,0)
 }
 for (let y=0 ; y <= height ; y+=10) {
   //line(0,0,width,y)
   //line(width,0,0,y)
   line(width,y,0,y)
 }
}

const sketch = p => {
  p.setup = () => {
    //キャンバスを作成
    const canvas = p.createCanvas(600,425);
    canvas.id = '__P5sc__';
    //背景色
    p.background('#eee');
    p.stroke('#aaa');
  }
  p.draw = () => {
    if (p.mouseIsPressed) {
      p.fill(0,0,0,10);
    } else {
      p.fill('#fff');
    }
    p.line(p.mouseX, p.mouseY, 150, 150);     
  }
}
new p5(sketch, 'editor');