Day: May 26, 2021

Today I’d like to show you how to code a special cursor effect. Custom cursors have been very popular and there’s so many creative possibilities that can enhance a certain design and an interaction logic.

Let’s have a look how to create a fullscreen crosshair cursor in SVG and how to distort the cursors’s lines with an SVG filter when hovering over links. We’ll also add a nice hover animation for some menu items using Splitting.js.

The Markup

For the SVG cursor we want a singe SVG for each line that has enough of space to get the distortion effect applied to it:

<div class="cursor">
	<svg class="cursor__line cursor__line--horizontal" viewBox="0 0 200 20" preserveAspectRatio="none">
		<line class="cursor__line-element" x1="0" y1="10" x2="200" y2="10" shape-rendering="crispEdges" vector-effect="non-scaling-stroke" />
	</svg>
	<svg class="cursor__line cursor__line--vertical" viewBox="0 0 20 200" preserveAspectRatio="none">
		<line class="cursor__line-element" x1="10" y1="0" x2="10" y2="200" shape-rendering="crispEdges" vector-effect="non-scaling-stroke" />
	</svg>
</div>

We’ll add the filters like this:

<div class="cursor">
	<svg class="cursor__line cursor__line--horizontal" viewBox="0 0 200 20" preserveAspectRatio="none">
		<defs>
			<filter id="filter-noise-x" x="-50%" y="-50%" width="200%" height="200%" 
			filterUnits="objectBoundingBox">
				<feTurbulence type="fractalNoise" baseFrequency="0" numOctaves="1" result="warp" />
				<feOffset dx="-30" result="warpOffset" />
				<feDisplacementMap xChannelSelector="R" yChannelSelector="G" scale="30" in="SourceGraphic" in2="warpOffset" />
			</filter>
		</defs>
		<line class="cursor__line-element" x1="0" y1="10" x2="200" y2="10" shape-rendering="crispEdges" vector-effect="non-scaling-stroke" />
	</svg>
	<svg class="cursor__line cursor__line--vertical" viewBox="0 0 20 200" preserveAspectRatio="none">
		<defs>
			<filter id="filter-noise-y" x="-50%" y="-50%" width="200%" height="200%" 
			filterUnits="objectBoundingBox">
				<feTurbulence type="fractalNoise" baseFrequency="0" numOctaves="1" result="warp" />
				<feOffset dy="-30" result="warpOffset" />
				<feDisplacementMap xChannelSelector="R" yChannelSelector="G" scale="30" in="SourceGraphic" in2="warpOffset" />
			</filter>
		</defs>
		<line class="cursor__line-element" x1="10" y1="0" x2="10" y2="200" shape-rendering="crispEdges" vector-effect="non-scaling-stroke" />
	</svg>
</div>

Let’s set up our menu with some data-splitting attributes:

<nav class="menu">
	<a href="#content-1" class="menu__item">
		<span data-splitting class="menu__item-title">Maputo</span>
		<span data-splitting class="menu__item-sub">Nights</span>
	</a>
	<a href="#content-1" class="menu__item">
		<span data-splitting class="menu__item-title">Gaborone</span>
		<span data-splitting class="menu__item-sub">Vibes</span>
	</a>
	<a href="#content-1" class="menu__item">
		<span data-splitting class="menu__item-title">Kinshasa</span>
		<span data-splitting class="menu__item-sub">Walks</span>
	</a>
</nav>

The CSS

First, we need to hide our cursor by default, and we just want to show it if the user has a pointing device, like a mouse. So we add a media query with the any-pointer media feature:

.cursor {
	display: block;
}

@media (any-pointer:fine) {
	.cursor {
		position: fixed;
		top: 0;
		left: 0;
		display: block;
		pointer-events: none;
		z-index: 1001;
	}

	.no-js .cursor {
		display: none;
	}

	.cursor__line {
		position: fixed;
		display: block;
		will-change: transform, opacity;
	}
	
	.cursor__line--horizontal {
		top: -10px;
		left: -10%;
		width: 120%;
		height: 20px;
	}
	
	.cursor__line--vertical {
		left: -10px;
		top: -10%;
		height: 120%;
		width: 20px;
	}
	
	.cursor__line-element {
		fill: none;
		stroke: var(--cursor-stroke);
		stroke-width: var(--cursor-stroke-width);
	}

}

The variables are define in the body.

For the menu, we’ll use some flexbox magic to lay out the menu items beneath each other:

.menu {
	display: flex;
	flex-direction: column;
	width: 100vw;
	height: calc(100vh - 13rem);
	position: relative;
	justify-content: flex-start;
	align-items: center;
}

.menu {
	text-align: center;
	padding-top: 10vh;
}

.menu__item {
	display: inline-block;
	margin-bottom: 3rem;
	text-decoration: none;
	color: var(--color-menu);
	font-family: vortice-concept, sans-serif;
}

.menu__item-title {
	line-height: 1;
	font-size: 7.5vw;
}

.menu__item-sub {
	font-size: 1.5vw;
	display: block;
}

@media screen and (min-width: 53em) {
	.menu {
		height: 100vh;
		justify-content: center;
	}
}

The JavaScript

Let’s create our custom cursor. So we have two SVGs, one for each line. As we saw in the markup earlier, each one of the SVGs will include a filter that we’ll apply to the respective line when hovering over a menu link.

Let’s start coding the entry JavaScript file (index.js):

import { Cursor } from './cursor';

// initialize custom cursor
const cursor = new Cursor(document.querySelector('.cursor'));

// mouse effects on all links
[...document.querySelectorAll('a')].forEach(link => {
    link.addEventListener('mouseenter', () => cursor.enter());
    link.addEventListener('mouseleave', () => cursor.leave());
});

Now, let’s create a class for the cursor (in cursor.js):

import { gsap } from 'gsap';
import { getMousePos } from './utils';

// Track the mouse position and update it on mouse move
let mouse = {x: 0, y: 0};
window.addEventListener('mousemove', ev => mouse = getMousePos(ev));

export class Cursor {
    constructor(el) {
    }
    // hovering over a link
    enter() {
    }
    // hovering out a link
    leave() {
    }
    // create the turbulence animation timeline on the cursor line elements
    createNoiseTimeline() {
    }
    // render styles and loop
    render() {
        // ...
        requestAnimationFrame(() => this.render());
    }
}

What we do here is to update the mouse position as we move the mouse around. For that, we use the getMousePos function (in utils.js).

Let’s move on to the next interesting part:

...
constructor(el) {
    // main DOM element which includes the 2 svgs, each for each line
    this.DOM = {el: el};
    // both horizontal and vertical lines
    this.DOM.lines = this.DOM.el.children;
    [this.DOM.lineHorizontal, this.DOM.lineVertical] = this.DOM.lines;
    // hide initially
    gsap.set(this.DOM.lines, {opacity: 0});
    ...
}
...

We initialize the line DOM elements and hide them initially.

We want to update the lines transform (translation values) as we move the mouse. For that, let’s create an object that stores the translation state:

...
constructor(el) {
    ...
    // style properties that will change as we move the mouse (translation)
    this.renderedStyles = {
        tx: {previous: 0, current: 0, amt: 0.15},
        ty: {previous: 0, current: 0, amt: 0.15}
    };
    ...
}
...

With interpolation, we can achieve a smooth animation effect when moving the mouse. The “previous” and “current” values are the values we’ll be interpolating. The current value of one of these “animatable” properties will be one between these two values at a specific increment. The value of “amt” is the amount to interpolate. As an example, the following formula calculates our current translationX value:

this.renderedStyles.tx.previous = lerp(this.renderedStyles.tx.previous, this.renderedStyles.tx.current, this.renderedStyles.tx.amt);

...
constructor(el) {
    ...
    // svg filters (ids)
    this.filterId = {
        x: '#filter-noise-x',
        y: '#filter-noise-y'
    };
    // the feTurbulence elements per filter
    this.DOM.feTurbulence = {
        x: document.querySelector(`${this.filterId.x} > feTurbulence`),
        y: document.querySelector(`${this.filterId.y} > feTurbulence`)
    }
    // turbulence current value
    this.primitiveValues = {turbulence: 0};
    // create the gsap timeline that will animate the turbulence value
    this.createNoiseTimeline();
}
...

Next, we initialize the filter ids, the feTurbulence elements for each SVG filter (one per line) and also the current turbulence value. Then we create the GSAP timeline that will take care of updating the baseFrequency of each filter with the current turbulence value. Here’s how that timeline and the methods that start/stop it look like:

...
createNoiseTimeline() {
    // turbulence value animation timeline:
    this.tl = gsap.timeline({
        paused: true,
        onStart: () => {
            // apply the filters for each line element
            this.DOM.lineHorizontal.style.filter = `url(${this.filterId.x}`;
            this.DOM.lineVertical.style.filter = `url(${this.filterId.y}`;
        },
        onUpdate: () => {
            // set the baseFrequency attribute for each line with the current turbulence value
            this.DOM.feTurbulence.x.setAttribute('baseFrequency', this.primitiveValues.turbulence);
            this.DOM.feTurbulence.y.setAttribute('baseFrequency', this.primitiveValues.turbulence);
        },
        onComplete: () => {
            // remove the filters once the animation completes
            this.DOM.lineHorizontal.style.filter = this.DOM.lineVertical.style.filter = 'none';
        }
    })
    .to(this.primitiveValues, { 
        duration: 0.5,
        ease: 'power1',
        // turbulence start value
        startAt: {turbulence: 1},
        // animate to 0
        turbulence: 0
    });
}
enter() {
    // start the turbulence timeline
    this.tl.restart();
}
leave() {
    // stop the turbulence timeline
    this.tl.progress(1).kill();
}
...

The animation will change the turbulence value (which starts at 1 and ends at 0) and apply it to each feTurbulence’s baseFrequency attribute. The filters get applied to the lines in the beginning and removed once the animation is completed.

To finalize the constructor method we fade in the lines and start updating the translation values the first time we move the mouse:

...
constructor(el) {
    ...
    import { lerp, getMousePos } from './utils';
    ...
    // on first mousemove fade in the lines and start the requestAnimationFrame rendering function
    this.onMouseMoveEv = () => {
        this.renderedStyles.tx.previous = this.renderedStyles.tx.current = mouse.x;
        this.renderedStyles.ty.previous = this.renderedStyles.ty.previous = mouse.y;
        gsap.to(this.DOM.lines, {duration: 0.9, ease: 'Power3.easeOut', opacity: 1});
        requestAnimationFrame(() => this.render());
        window.removeEventListener('mousemove', this.onMouseMoveEv);
    };
    window.addEventListener('mousemove', this.onMouseMoveEv);
}
...

Now we’re only missing the actual method that updates the lines’ translation values as we move the mouse:

...
render() {
    // update the current translation values
    this.renderedStyles['tx'].current = mouse.x;
    this.renderedStyles['ty'].current = mouse.y;
    // use linear interpolation to delay the translation animation
    for (const key in this.renderedStyles ) {
        this.renderedStyles[key].previous = lerp(this.renderedStyles[key].previous, this.renderedStyles[key].current, this.renderedStyles[key].amt);
    }
    // set the new values
    gsap.set(this.DOM.lineVertical, {x: this.renderedStyles['tx'].previous});
    gsap.set(this.DOM.lineHorizontal, {y: this.renderedStyles['ty'].previous});
    // loop this until the end of time
    requestAnimationFrame(() => this.render());
}

As an extra, let’s add a little glitch effect to the menu items texts when we hover over them. We’ll use the Splitting library to split the menu texts into spans/chars so we can animate each one individually. We want to change the translation values of each character and also it’s color. Let’s update our index.js file:

import { Cursor } from './cursor';
import { MenuItem } from './menuItem';
// Splitting (used to split the menu item texts to spans/characters)
import 'splitting/dist/splitting.css';
import 'splitting/dist/splitting-cells.css';
import Splitting from 'splitting';

// initialize Splitting
const splitting = Splitting();

// initialize custom cursor
const cursor = new Cursor(document.querySelector('.cursor'));

// Menu Items
[...document.querySelectorAll('.menu > a')].forEach(el => new MenuItem(el));

// mouse effects on all links
[...document.querySelectorAll('a')].forEach(link => {
    link.addEventListener('mouseenter', () => cursor.enter());
    link.addEventListener('mouseleave', () => cursor.leave());
});

Assuming we have data-splitting set in all elements we want to split into chars, then we only need to call Splitting() and we then have each text split into a bunch of spans, for every letter of the text.

Let’s now have a look at our MenuItem class:

import { gsap } from 'gsap';

export class MenuItem {
    constructor(el) {
        this.DOM = {el};
        // all text chars (Splittingjs) 
        this.DOM.titleChars = this.DOM.el.querySelectorAll('span.char');
        // initial and final colors for each span char (before and after hovering)
        const bodyComputedStyle = getComputedStyle(document.body);
        this.colors = {
            initial: bodyComputedStyle.getPropertyValue('--color-menu'), 
            final: bodyComputedStyle.getPropertyValue('--color-link')
        };
        this.initEvents();
    }
    ...
}

We get a reference to all the characters of the menu item text and also it’s initial and final colors for the hover animation.

...
initEvents() {
    this.onMouseEnterEv = () => this.onMouseEnter();
    this.DOM.el.addEventListener('mouseenter', this.onMouseEnterEv);

    this.onMouseLeaveEv = () => this.onMouseLeave();
    this.DOM.el.addEventListener('mouseleave', this.onMouseLeaveEv);
}
...

We initialize the mouseenter/mouseleave events which will triggger the animation on the characters.

When hovering over a menu item we will randomly change its characters position and color, and when hovering out we reset the original color:

onMouseEnter() {
    if ( this.leaveTimeline ) {
        this.leaveTimeline.kill();
    }

    // let's try to do an animation that resembles a glitch effect on the characters
    // we randomly set new positions for the translation and rotation values of each char and also set a new color
    // and repeat this for 3 times
    this.enterTimeline = gsap.timeline({
        defaults: {
            duration: 0.05,
            ease: 'power3',
            x: () => gsap.utils.random(-15, 15),
            y: () => gsap.utils.random(-20, 10),
            rotation: () => gsap.utils.random(-5, 5),
            color: () => gsap.utils.random(0, 3) < 0.5 ? this.colors.final : this.colors.initial
        }
    })
    // repeat 3 times (repeatRefresh option will make sure the translation/rotation values will be different for each iteration)
    .to(this.DOM.titleChars, {
        repeat: 3,
        repeatRefresh: true
    }, 0)
    // reset translation/rotation and set final color
    .to(this.DOM.titleChars, {
        x: 0, 
        y: 0, 
        rotation: 0,
        color: this.colors.final
    }, '+=0.05');
}
onMouseLeave() {
    // set back the initial color for each char
    this.leaveTimeline = gsap.timeline()
    .to(this.DOM.titleChars, {
        duration: 0.4,
        ease: 'power3',
        color: this.colors.initial
    });
}

And that is all!

I hope this has not been too difficult to follow and that you have gained some insight into constructing this fancy effect.

Please let me know if you have any question @codrops or @crnacura.

Thank you for reading!

The post How to Code a Crosshair Mouse Cursor with Distortion Hover Effect appeared first on Codrops.