Full Page Parallax Effect

Scroll down and up to see the effect!

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@import url(https://fonts.googleapis.com/css?family=Montserrat); // ------------- MIXINS ------------- // @mixin transition($time, $property: all, $easing: ease-in) { transition: $property $time $easing; } // ------------- VARIABLES ------------- // $parallax-offset: 30vh; $content-offset: 40vh; $transition-speed: 1.2s; $slide-number: 3; html, body { overflow: hidden; } .background { background-size: cover; background-repeat: no-repeat; background-position: center center; overflow: hidden; will-change: transform; backface-visibility: hidden; height: 100vh + $parallax-offset; position: fixed; width: 100%; transform: translateY($parallax-offset); @include transition($transition-speed, all, cubic-bezier(0.22, 0.44, 0, 1)); &:before { content: ""; position: absolute; width: 100%; height: 100%; top: 0; left: 0; right: 0; bottom: 0; background-color: rgba(0,0,0,.3); } &:first-child { background-image: url(https://i.postimg.cc/kXq9Qmnj/bgd1.jpg); transform: translateY(-$parallax-offset / 2); .content-wrapper { transform: translateY($parallax-offset /2); } } &:nth-child(2) { background-image: url(https://i.postimg.cc/W14vywqg/photo-1424746219973-8fe3bd07d8e3.jpg); } &:nth-child(3) { background-image: url(https://i.postimg.cc/TY0xQ41T/photo-1433840496881-cbd845929862.jpg); } } /* Set stacking context of slides */ @for $i from 1 to ($slide-number + 1) { .background:nth-child(#{$i}) { z-index: ($slide-number + 1) - $i; } } .content { &-wrapper { height: 100vh; display: flex; justify-content: center; text-align: center; flex-flow: column nowrap; color: #fff; font-family: Montserrat; text-transform: uppercase; transform: translateY($content-offset); will-change: transform; backface-visibility: hidden; @include transition($transition-speed + .5, all, cubic-bezier(0.22, 0.44, 0, 1)); } &-title { font-size: 12vh; line-height: 1.4; } } // ------------- SET TRANSFORM VALUES ------------- // .background.up-scroll { transform: translate3d(0,-$parallax-offset / 2,0); .content-wrapper { transform: translateY($parallax-offset / 2); } + .background { transform: translate3d(0,$parallax-offset,0); .content-wrapper { transform: translateY($parallax-offset); } } } .background.down-scroll { transform: translate3d(0,-(100vh + $parallax-offset),0); .content-wrapper { transform: translateY($content-offset); } + .background:not(.down-scroll) { transform: translate3d(0,-$parallax-offset / 2,0); .content-wrapper { transform: translateY($parallax-offset / 2); } } } // ------------- VARIABLES ------------- // var ticking = false; var isFirefox = (/Firefox/i.test(navigator.userAgent)); var isIe = (/MSIE/i.test(navigator.userAgent)) || (/Trident.*rv\:11\./i.test(navigator.userAgent)); var scrollSensitivitySetting = 30; //Increase/decrease this number to change sensitivity to trackpad gestures (up = less sensitive; down = more sensitive) var slideDurationSetting = 600; //Amount of time for which slide is "locked" var currentSlideNumber = 0; var totalSlideNumber = $(".background").length; // ------------- DETERMINE DELTA/SCROLL DIRECTION ------------- // function parallaxScroll(evt) { if (isFirefox) { //Set delta for Firefox delta = evt.detail * (-120); } else if (isIe) { //Set delta for IE delta = -evt.deltaY; } else { //Set delta for all other browsers delta = evt.wheelDelta; } if (ticking != true) { if (delta <= -scrollSensitivitySetting) { //Down scroll ticking = true; if (currentSlideNumber !== totalSlideNumber - 1) { currentSlideNumber++; nextItem(); } slideDurationTimeout(slideDurationSetting); } if (delta >= scrollSensitivitySetting) { //Up scroll ticking = true; if (currentSlideNumber !== 0) { currentSlideNumber--; } previousItem(); slideDurationTimeout(slideDurationSetting); } } } // ------------- SET TIMEOUT TO TEMPORARILY "LOCK" SLIDES ------------- // function slideDurationTimeout(slideDuration) { setTimeout(function() { ticking = false; }, slideDuration); } // ------------- ADD EVENT LISTENER ------------- // var mousewheelEvent = isFirefox ? "DOMMouseScroll" : "wheel"; window.addEventListener(mousewheelEvent, _.throttle(parallaxScroll, 60), false); // ------------- SLIDE MOTION ------------- // function nextItem() { var $previousSlide = $(".background").eq(currentSlideNumber - 1); $previousSlide.removeClass("up-scroll").addClass("down-scroll"); } function previousItem() { var $currentSlide = $(".background").eq(currentSlideNumber); $currentSlide.removeClass("down-scroll").addClass("up-scroll"); }

Apolinarija, i zašto je potrebna matematika