pg <- NULL

settings <- function() {
    size(200, 200)
}

setup <- function() {
    pg <- createGraphics(100, 100)
}

draw <- function() {
    background(204)
    pg$beginDraw()
    pg$stroke(0, 102, 153)
    pg$line(0, 0, mouseX, mouseY)
    pg$endDraw()
    image(pg, 50, 50)
}

# Click to clear the PGraphics object
mousePressed <- function() {
    pg$beginDraw()
    pg$clear()
    pg$endDraw()
}