Drawing like a 5-year-old

Dr. Ben Swift

06 Sep '17

who drew pictures as a 5yo?

your “hour of code”

https://hourofcode.com/

teach the computer to draw a picture

learn how to deal with its tantrums

share your stuff with the world

p5.js

open up a web browser (e.g. Firefox) and head to https://editor.p5js.org/

(optional) if you want to share your work later, create an account (it’s super-easy, and free)

edit the code

function setup() {
  createCanvas(800, 800);
}

function draw() {
  // add this next line on your computer
  background(220);
  rect(0, 0, 100, 100);
}

don’t forget to hit the play button!

collaboration

can you draw the square differently?

  • bottom right
  • tall and skinny
  • short and fat
  • filling the whole top right quarter

new shapes

what happens if you replace rect with ellipse?

you can have multiple lines of code in the draw function—can you draw a square and a circle on top of one another?

colours

colours

put one of these before your rect line:

fill(255, 0, 0);
// or
stroke(15, 180, 0);

try changing the numbers around…

moar colours

fill(255, 0, 0); // each value from 0-255
R G B

how do you know what instructions the computer understands?

use the reference

dealing with errors

like a 5-year-old, you need to be specific

don’t forget any brackets, commas, etc.

learn to understand the tantrums:

ReferenceError: sdfsd is not defined (sketch: line 8)
SyntaxError: missing ) after argument list (sketch: line 12)

smiley face

function setup() {
  createCanvas(800, 800);
  noStroke();
}

function draw() {
  background(120);
  // set colour to yellow & draw face
  fill(255, 255, 0);
  ellipse(400, 400, 400, 400);
  
  // set colour to black & draw eyes/mouth
  fill(0);
  ellipse(300, 350, 70, 70);
  ellipse(500, 350, 70, 70);
  ellipse(400, 500, 120, 70);
}

interaction

replace one of the numbers (e.g. a 100) with mouseX

replace one of the numbers with frameCount

do some maths (e.g. +, -, *, /, %, …)

what have we done today?

programming (like any sufficiently complex activity) uses lots of jargon & technical terms

but in the end, it’s just about telling your computer what to do in language it understands

there’s lots more!

if you created an account earlier, then you’ll have a share tab along the top of the screen

going further

https://p5js.org/reference/

https://p5js.org/examples/

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