P5.js Reference: Functions and Utilities

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P5.js is a powerful JavaScript library that simplifies the creation of interactive graphics, animations, and multimedia applications in the browser. In this reference, we'll take a closer look at the key functions and utilities provided by p5.js to help you create stunning projects with ease.

Setup and Draw Functions

When working with p5.js, you'll often start by defining two essential functions: setup() and draw().

setup()

The setup() function is called once when the program begins, and it's where you can perform initial configurations, such as setting the canvas size or loading external resources.

function setup() {
    createCanvas(800, 600);
}

draw()

The draw() function is called repeatedly in a loop, allowing you to create animations by updating the screen contents. This loop is executed at a default frame rate of 60 FPS, but you can modify it using frameRate().

function draw() {
    background(0);
    ellipse(mouseX, mouseY, 50, 50);
}

Graphics

P5.js provides a variety of functions for creating and manipulating graphics on the canvas.

Basic Shapes

You can draw basic shapes such as circles, rectangles, and lines using functions like ellipse(), rect(), and line().

ellipse(50, 50, 25, 25); // Draw a circle
rect(100, 100, 50, 50); // Draw a square
line(0, 0, 100, 100); // Draw a diagonal line

Colors and Styles

Customize the appearance of your graphics with functions like fill(), stroke(), and strokeWeight().

fill(255, 0, 0); // Red fill color
stroke(0, 255, 0); // Green stroke color
strokeWeight(5); // Stroke weight of 5 pixels

Transformations

Manipulate graphics on the canvas with translation, rotation, and scaling using translate(), rotate(), and scale() functions.

translate(100, 100); // Move the origin to (100, 100)
rotate(PI / 4); // Rotate the canvas by 45 degrees
scale(2, 2); // Scale the canvas by a factor of 2

Interactivity

P5.js makes it simple to interact with users through keyboard, mouse, and touch events.

Mouse Events

Capture mouse events like clicks and movements using functions such as mousePressed(), mouseReleased(), and mouseMoved().

function mousePressed() {
    console.log("Mouse button pressed");
}

function mouseReleased() {
    console.log("Mouse button released");
}

function mouseMoved() {
    console.log("Mouse moved");
}

Keyboard Events

Detect keyboard input with functions like keyPressed(), keyReleased(), and keyTyped().

function keyPressed() {
    console.log("Key pressed:", keyCode);
}

function keyReleased() {
    console.log("Key released:", keyCode);
}

function keyTyped() {
    console.log("Key typed:", key);
}

Touch Events

Respond to touch events on mobile devices using functions such as touchStarted(), touchMoved(), and touchEnded().

function touchStarted() {
    console.log("Touch started");
}

function touchMoved() {
    console.log("Touch moved");
}

function touchEnded() {
    console.log("Touch ended");
}

Utilities

P5.js provides handy utility functions for common tasks like generating random numbers or mapping values.

Random Values

Generate random numbers using the random() function.

let randomValue = random(0, 100); // A random value between 0 and 100

Mapping Values

Map a value from one range to another using the map() function.

let mappedValue = map(50, 0, 100, 0, 255); // Map 50 from range 0-100 to range 0-255

This reference only scratches the surface of the numerous functions and utilities available in p5.js. For a more comprehensive list, check out the official p5.js reference. Happy coding!