Why are constants not defined when using p5.js in instance mode?

Question

I'm probably missing something very obvious here. I can use p5.js in global mode and use constants for textAlign with no problem, e.g. CENTER.

Here is global mode code where it works fine:

function setup() {
  var canvas = createCanvas(720, 400);  
  canvas.parent('main_canvas');
};

function draw() { 
  textSize(32);
  textAlign(CENTER);
  text("word", 50, 50);
};

However when I try using CENTER in instance mode I get:

Uncaught ReferenceError: CENTER is not defined:

Here is instance mode code where it fails:

var s = function (p) {
  p.setup = function() {
    p.createCanvas(720, 400);
  };

  p.draw = function() {
    p.textSize(32);
    p.textAlign(CENTER);
    p.text("word", 50, 50);
  };
};
var myp5 = new p5(s,'main_canvas');

Any ideas on what I am missing here?

The point of instance mode is to keep everything related to p5.js out of the global namespace, even constants like CENTER, so this is by design. — ggorlen
– ggorlen, Commented Jan 13, 2022 at 0:14

Kevin Workman · Accepted Answer · 2016-10-11 12:43:50Z

4

In global mode, all the P5.js functions and variables are added to the global namespace. In instance mode, all the P5.js functions and variables are added to the variable passed into the sketch function (in your case, your p variable).

To use the CENTER variable, you have to get at it through the p variable.

In other words, you need to do this:

p.textAlign(p.CENTER);

You'll also have to do this with other variables, like mouseX and mouseY.

answered Oct 11, 2016 at 12:43

Kevin Workman

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2 Comments

e_r Over a year ago

The shame I feel right now knows no bounds. Thanks.

Kevin Workman Over a year ago

@e_r I think you've just described 75% of all programming! :p

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