p5.js mousePressed() Function

The mousePressed() function in p5.js works when mouse clicked on the document. The mouseButton variable is used to specify which button is pressed. The touchStarted() function is used instead of mousePressed() function if mousePressed() function is not defined.

Syntax:

mousePressed(Event)

Below programs illustrate the mousePressed() function in p5.js:

Example 1: This example uses mousePressed() function.

function setup() {

    // Create Canvas
    createCanvas(500, 500);
}

let value = 0;

function draw() {

    // Set background color
    background(200);

    // Fill the color
    fill(value, value-50, value-100);

    // Create rectangle
    rect(25, 25, 460, 440);

    // Set the color of text
    fill('lightgreen');

    // Set font size
    textSize(15);

    // Display content
    text('Keep on Clicking the Mouse Across'
        + 'the page \nto change Canvas Color.',
            windowHeight/10, windowWidth/4);
}

function mousePressed() {

    value = value + 5;

    if (value > 255) {
        value = 0;
    }
}

Output:

Example 2:

let valueX;
let valueY;

function setup() {

    // Create Canvas
    createCanvas(500, 500);
}

function draw() {

    // Set background color
    background(200);

    // Set the text color
    fill('green');

    // Set text size
    textSize(25);

    text('Drag mouse to change color', 30, 30);

    // Fill color according to mouseMoved()
    fill(valueX, 255-valueY, 255-valueX);

    // Draw ellipse
    ellipse(mouseX, mouseY, 115, 115);
}

function mousePressed() {
    valueX = mouseX%255;
    valueY = mouseY%255;
}

Output:

Reference: https://p5js.org/reference/#/p5/mousePressed