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Hello! I'm trying to add a button to my 3-Gear Spirograph model but I get an error message: TypeError: fxn.bind is not a function. The sliders work so I have p5.dom.js in the right place. Can anybody help?

Peter

Here's my code:

var R = 275;// radius of big circle
var r = 203;//radius of circle 2
var r3 = 151;//radius of circle 3
var theta = 0;
var p = .8;//proportion of little circle
var trail = false;
var rSlider,r3Slider,button;

function setup(){
createCanvas(600,600);
background(0);
// create sliders
rSlider = createSlider(0, 255, 100);
rSlider.position(20, 20);
r3Slider = createSlider(0, 255, 0);
r3Slider.position(20, 50);
button = createButton('Show Trail');
button.position(20, 80);
button.mousePressed(trail);
}

function draw(){
frameRate(10);
var r = rSlider.value();
var r3 = r3Slider.value();

if (!trail){
background(0);
}
fill(255);
textSize(16);
fill(255,0);//transparent
translate(width/2,height/2); //to center of big circle
stroke(255);
if (!trail){
ellipse(0,0,2*R,2*R); //draw big circle
}
rotate(theta); //rotate to angle of circle2
translate(R - r,0); //go to center of circle2
if (!trail){
ellipse(0,0,2*r,2*r); //draw little circle
}
var phi = -R/r*theta;//angle of rotation of circle 2
rotate(phi); //rotate phi
fill(255,0);
translate(r - r3,0); //go to center of circle 3
if (!trail){
ellipse(0,0,2*r3,2*r3); //draw little circle
}
var angle3 = -r/r3*phi;//angle of rotation of circle 3
rotate(angle3);
line(0,0,p*r3,0);//draw using just this! cool.
translate(p*r3,0);
fill(255,0,0);
ellipse(0,0,2,2);//or point(...
theta += 0.05;
}

function trail(){
var trail = true;
}

• edited May 2015

You have a naming clash, and need to better understand scope: var trail and function trail() are in the same scope and that's the likely cause of your problem. How about calling your function setTrail()? You'll then have to remove the 'var' in front of 'trail' in that function; otherwise you're creating a variable local only to the function; and not setting the value of the trail variable at the root of your sketch.

• Thanks! That cleared that up.