int radiusSize = 20; color theColour = color(255, 0, 0); void setup() { size(400, 400); initCommandLine(); noStroke(); ellipseMode(RADIUS); } // demonstrate changing any parameter while running void draw() { background(40); fill(theColour); ellipse(200,200,radiusSize,radiusSize); } void radius(int x){ radiusSize = x; redraw(); } void colour(color x, color y, color z){ theColour = color(x,y,z); redraw(); }