Clearing createGraphics() canvas from p5js renderer

Question

p5js has a clear() function which clears everything from the screen. I want to keep the canvas created by createCanvas() but clear the createGraphics() one only. How can I do this ?

//something like this
var canvas2;
function setup() {
  createCanvas(400, 400);
  canvas2 = createGraphics(400,400);
  canvas2.clear()
  noLoop()
}

function draw() {
  fill(255,0,0)
  rect(60,60,40,40)
  canvas2.fill(20,44,240);
  canvas2.rect(20,20,40,40);
  image(canvas2,0,0)
}

function mousePressed() {
  //something which clears the createGraphics() canvas only and keeps the createCanvas() one
}

Answer 1

You can clear the content of a graphics object using its clear() function. Here's an example:

var canvas2;

function setup() {
  createCanvas(400, 400);
  
  canvas2 = createGraphics(400,400);
  canvas2.fill(20,44,240);
  canvas2.rect(20,20,40,40);
}

function draw() {
  background(255);

  fill(255,0,0)
  rect(60,60,40,40)

  image(canvas2,0,0)
}

function mousePressed() {
  canvas2.clear();
}

I moved the canvas2.rect(20, 20, 40, 40) call to be inside the setup() function, because otherwise you're redrawing to the canvas even after you clear it. I also removed your noLoop() call so that you could see the result of clearing the canvas.