Creative

Computation
for Visual

Communication
Design

 

WEEK 1 DAY 2

What did we learn?

  • JavaScript syntax

  • Screen coordinate system

  • Program flow

  • What are functions

  • How to draw basic shapes

  • How to calculate coordinates

  • How to change fill, stroke, etc.

  • How to add interaction with mouse

  • Debugging

  • Borrowing code

DON'T WORRY!

Coding Workshop 1.2

Basic concepts in computation

  • MEMORY

    • Storing data and accessing it later

      • Variables, arrays, objects

  • SEQUENCE

    • Running instructions in order

      • Functions, algorithms

  • SELECTION

    • Making choices

      • Conditionals and logic (if, else, and, or, not)

  • REPETITION

    • Doing the same thing more than once

      • Loops (for, while)

Variables

function setup(){
    //set canvas size 500*500px
    createCanvas(500,500);
    background(255,0,0); //red background
    strokeWeight(4); //set strokeWeight
    stroke(0); //set stroke color to black
}
function draw(){
    fill(255); //set fill colour white
    ellipse(250,250,350,350); //draw face
    fill(0); //set fill colour black
    ellipse(200,200,50,100); //draw eye
    ellipse(300,200,50,100); // draw eye
    fill(255,100,250); //set fill colour pink
    ellipse(250,250,40,40); //draw nose
    fill(255,100,250); //set fill colour pink
    line(200, 300, 300, 300); //draw mouth
}

PROBLEM:

How to keep track of all the numbers and edit them easily?

Variables

  • Variables are used to label and store data

  • This data can then be used throughout your program

  • Variables make code more flexible

    • Instead of changing every number by hand, you can change variable values

  • We have already used some built-in variables

    • mouseX and mouseY store the cursor position

    • width and height store the size of canvas

Variables

myVariable

value

Variable syntax

let myVariable;
myVariable = 100;
let myVariable = 100;

Declare a variable with a name

Assign a value to the variable

Declare and assign value with one statement

Variable syntax

"Let there be light"

Variable syntax

let x = 3; // assign value 3 to variable x
let y = 6; // assign value 6 to variable y
x = 4; // re-assign value 4 to variable x
let sum = x + y; // assign value 10 to variable sum
let price = 9.99; // assign a decimal number
let name = "Mickey Mouse"; // assign a string

  • You can re-assign variables

    • Give the variable a new value

  • You can perform calculations with variables

  • You can also store other things than numbers

Other variable types

const x = 3; // assign value 3 to a constant variable x
x = 4; // ERROR! const can not be re-assigned
const y; //ERROR! const has to be declared with a value

  • const is used to declare a constant variable that can not be re-assigned

    • ​Makes the code more explicit

      • Tells the reader which values are going to be changing

  • var is similar to let but has a different scope and can be used before declaration 

    • ​Not recommended after 2015

Variable scope

  • Variables are recognised and accessible only inside their scope

  • Defining a variable outside all {} blocks makes its scope global

    • The variable can be used everywhere

  • Defining a variable inside a block makes it scope local

    • The variable can be used in only that block​

Exercise 0: Before variables

LET'S MAKE THIS CODE MORE FLEXIBLE AND ELEGANT USING VARIABLES!

Exercise 1: Variables

Making things move

PROBLEM: HOW TO "ANIMATE" SHAPES?

Making things move

  • The draw function runs ~60 times per second

  • If we are drawing the same frame over and over again the sketch looks static

  • Changing slightly what we are drawing in every frame will appear as movement

    • Like a frame-by-frame animation!

Making things move

  • One way we can do this is incrementing (increasing) the value of a variable every time the draw function runs

i = i+1;
i+=1;

redefine i with the previous value of i plus 1

a shorthand version of the same statement

i++;

even shorter version of the same statement

Exercise 2: Simple animation

Logic

PROBLEM: HOW TO MAKE THE ANIMATION LOOP BACK TO THE BEGINNING

Logic

  • So far our code is doing the same thing over and over

  • How can we make the code do different things in different conditions?

  • For this we need logic

    • “If the ball reaches the border, then go back to beginning”

Logic

  • Logic acts on boolean expressions

    • “The ball has reached the edge” can be TRUE or FALSE

  • Comparing values produces boolean expressions

    • “If the x-coordinate of the ball is larger than width of canvas”     

  • We can combine boolean expressions with logic operators

    • “If x is smaller than 0 OR x is larger than width”

Comparison operators

< //smaller than
> //greater than
<= //smaller than or equal to
>= //greater than or equal to
=== //equal to
!== //not equal to
let i = 3;
i < 7 //TRUE
i > 5 //FALSE
i >= 1
i <= 3.5
i === 2.9
i !== 3

Logic operators

&& //AND
|| //OR
! //NOT
let i = 3;
(i > 2) && (i < 7) 
(i < 1) || (i < 5)
!(i === 3)

Programmer humour:

 

!false

(it’s funny because it’s true)

 

 

Conditional statements

if(condition){
    //block of code to be executed
    //if the condition is true
}

if(condition){
    //executed if the condition is true
}
else {
    //executed if the condition is false
}

boolean expression

curly brackets

Exercise 3: Looping animation

Exercise 4: Bouncing ball

VARIATION: Exercise 5:

Advanced Bouncing ball

Conditional statements

if (condition1) {
  //executed if condition1 is true
}
else if (condition2) {
  //executed if the condition1 is false and condition2 is true
}
else {
  //executed if the condition1 is false and condition2 is false
}

Multiple conditions can be tested using the else-if structure

Exercise 6: Conditional Colours

More interaction

  • So far we have learned how to use the mouseX and mouseY variables which give the cursor coordinates

  • You can also trigger events with mouse clicks by using the mouseIsPressed variable

    • A boolean variable that is true when mouse is pressed

if (mouseIsPressed) {
  //do stuff when mouse is pressed
}

VARIATION: Exercise 7:

Conditional Drawing Tool

Recap

//defining variables
let i;
let i = 0;

//incrementing variables
i = i+1;
i += 1;
i++;

if(/*condition1*/){
    //executed if condition1 is true
}
else if(/*condition2*/){
    //executed if condition1 is false and condition2 is true
}
else{
    //executed if both conditions are false
}
//logic operators
&& //AND
|| //OR
! //NOT
//comparison operators
< //smaller than
> //greater than
<= //smaller than or equal to
>= //greater than or equal to
=== //equal to
!== //not equal to

//mouse interaction
mouseIsPressed; //true when mouse is pressed

Coding Assignment I:

Sigil

Coding Assignment I: Sigil

 

Sigil is a personalised, magical emblem that is often used for self-actualisation. The sigil symbolises a wish, an ambition, or an entity the user desires to summon. It can contain a monogram that represents the wish, and other abstract or representational elements that illustrate the desired outcome.

 

“Sigils help you to achieve goals, co-create your reality, self-actualize your potential and fulfill your deepest dreams and desires.”

 

“Modern corporate logos are a type of sigil.”

Coding Assignment I

If possible, we want to make our designs responsive, so that they can be scaled to any dimension.

Coding Assignment I

Whitney Museum identity by Experimental Jetset 2013

“Vital Question: can a mark be variable without at the same time forfeiting its mark-like character? Counter-question: what is typical about a mark, the proportion of the ‘configuration’? My answer is known: it is not and cannot be a question merely of proportions as such. Proportions can never be anything but good (or bad) relative to the task. But: in the structure of any sign, however great the number of variants, there is always one which must be declared to be the exemplar. The ‘configuration’ must not suffer as a result of the variability.”

Karl Gerstner: Designing Programmes (1964)

Coding Assignment I

  • Only use primitive shapes

    • Ellipse, rect, line, triangle, quad, point, arc

  • Use the width and height attributes

  • Use at least one variable (in a meaningful way)

  • Use max 2 colours

  • LEVEL 1 ADVANCED: Make the sigil responsive, so that it can be scaled to any size and dimension of the canvas. (See the Assignment 1 Template)

  • LEVEL 2 ADVANCED: Use conditional statements

  • LEVEL 3 ADVANCED: Animate the sigil!

Coding Assignment I: CONSTRAINTS

  • Add comments on the top of your code

    • Your name and date

    • Explain briefly the key features of your sigil. What is it for?

    • Reference any code you have copied from someone else

      • (No need to reference class examples

  • Add comments inline with your code

    • Explain how the code works

  • Make sure the code runs without errors

  • Submit the web editor link to your sketch in MyCourses

Coding Assignment I: INSTRUCTIONS

  • Consider which aspects of the sigil should be scalable and which should remain constant

    • What are the “initial” or “optimal” dimensions of your design?

  • We haven’t yet learned how to rotate shapes, draw custom shapes, or work with text. Think how to use the primitive shapes to bypass this.

Coding Assignment I: TIPS

To do before next Tuesday

  • Share your cool creations on Week 1 Showcase

  • Weekly Reading I

  • Coding Assignment I

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