Introduction to Generative Art

Objectives

• See how following a simple algorithm, or recipe, can be used to create pleasing visual patterns.
• Make use of selection statements to run different blocks of code.

What is generative art?

Generative art describes visual forms that are created wholly through the use of code.

The programmer makes decisions about how to write the code itself.

The programs authored by a generative artist use various types of input or random events to make decisions about how to structure the output each time the program is run.

In this way, running a generative art program several times will produce different output each time.

Here are some examples:

Setup

Please create a new playground titled Gen Art Intro.

Then copy and paste this code into the playground:

// Black borders
turtle.penColor = .black

// "Flip a coin"
let coin = Int.random(in: 1...2)

// Set color based on coin
if coin == 1 {
    turtle.fillColor = .red
} else {
    turtle.fillColor = .blue    
}

// Draw a circle
turtle.arc(radius: 100, angle: 360)

Now run the program several times. What do you notice?

Selection statements

Selection statements refer to structures in code that "select" a block of code to run based on a condition.

There are multiple types of programming language structures that allow for selection to occur.

In this discussion, we will look at if statements.

The general syntax is:

In that example, only when the condition evaluates to true does the block of code inside the { } brackets get selected to be run. Otherwise, the block of code is skipped.

Here is another example:

In this example, when the condition is true the first block of code runs. Otherwise, else, the second block of code runs.

When writing a condition we use comparison operators so that we can compare the left side of a condition to the right side.

Here is the complete list of comparison operators that can be used in an expression:

Extend

Stephen Boyd is an artist, based in Toronto, who has been making generative art for two decades.

He shared this post on Mastodon on September 28, 2023:

After reviewing his algorithm (or recipe) use your understanding of how to create shapes using the turtle in Swift Playgrounds to write code that implements it.

Think about how you might use functions and loops while authoring your code.