How can I change the color of navigation text on fullscreen scrolling based on background?
The name really speaks about it. Here is an example of what I am trying to achieve a background based navigation color change image
The problem is that it has to work with the site using a scrolling parallax type effect, here is the site I am trying to achieve with the demo site
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Change the scrolling script bit
Check the demo here
Created a function toggleHeaderColor
to check the current section. Since the scroll script indexes each section in order 0 (i.e. section_1) ,1 (i.e. section_2),2 (i.e. section_2),3 (i.e. section_3),4 (i.e. section_2) and so on
. Every time you scroll through it, it refreshes.
In the scrolling script, there are two function forms nextItem()
and previousItem()
, which we get at the current slide index, and on that we can call our function to switch the class dark
to the title elements.
JS:
var sectionBlock = $(".section-item");
var getCurrentSlideAttr = 0;
function toggleHeaderColor(getCurrentSlideAttr) {
if (getCurrentSlideAttr == 0) {
$(".menu-link, .menu-link-logo, .menu-link-last").removeClass("dark");
}
if (getCurrentSlideAttr == 1) {
$(".menu-link, .menu-link-logo, .menu-link-last").addClass("dark");
}
if (getCurrentSlideAttr == 2) {
$(".menu-link, .menu-link-logo, .menu-link-last").removeClass("dark");
}
if (getCurrentSlideAttr == 3) {
$(".menu-link, .menu-link-logo, .menu-link-last").removeClass("dark");
}
if (getCurrentSlideAttr == 4) {
$(".menu-link, .menu-link-logo, .menu-link-last").addClass("dark");
}
}
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;
var slideDurationSetting = 800;
var currentSlideNumber = 0;
var totalSlideNumber = $(".section-item").length;
function parallaxScroll(evt) {
if (isFirefox) {
delta = evt.detail * -120;
} else if (isIe) {
delta = -evt.deltaY;
} else {
delta = evt.wheelDelta;
}
if (ticking != true) {
if (delta <= -scrollSensitivitySetting) {
ticking = true;
if (currentSlideNumber !== totalSlideNumber - 1) {
currentSlideNumber++;
nextItem();
}
slideDurationTimeout(slideDurationSetting);
}
if (delta >= scrollSensitivitySetting) {
ticking = true;
if (currentSlideNumber !== 0) {
currentSlideNumber--;
}
previousItem();
slideDurationTimeout(slideDurationSetting);
}
}
}
function slideDurationTimeout(slideDuration) {
setTimeout(function() {
ticking = false;
}, slideDuration);
}
var mousewheelEvent = isFirefox ? "DOMMouseScroll" : "wheel";
window.addEventListener(mousewheelEvent, _.throttle(parallaxScroll, 60), false);
function nextItem() {
getCurrentSlideAttr = currentSlideNumber;
toggleHeaderColor(getCurrentSlideAttr);
var $previousSlide = $(".section-item").eq(currentSlideNumber - 1);
$previousSlide
.css("transform", "translate3d(0,-130vh,0)")
.find(".content-wrapper")
.css("transform", "translateY(40vh)");
currentSlideTransition();
}
function previousItem() {
//console.log($(".section-item").eq(currentSlideNumber).attr('id'))
getCurrentSlideAttr = currentSlideNumber;
toggleHeaderColor(getCurrentSlideAttr);
var $previousSlide = $(".section-item").eq(currentSlideNumber + 1);
$previousSlide
.css("transform", "translate3d(0,30vh,0)")
.find(".content-wrapper")
.css("transform", "translateY(30vh)");
currentSlideTransition();
}
function currentSlideTransition() {
var $currentSlide = $(".section-item").eq(currentSlideNumber);
$currentSlide
.css("transform", "translate3d(0,-15vh,0)")
.find(".content-wrapper")
.css("transform", "translateY(15vh)");
}
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Update
You can select specific text color over white / black background using css blend modes.
An example with specific colors (green over white and red over black in this case):
html, body {
margin: 0;
}
h1 {
position: fixed; top: 0; left: 0;
width: 100vw;
text-align: center;
mix-blend-mode: difference;
color: white;
z-index: 1;
}
div {
position: relative;
width: 100vw;
height: 100vh;
background: white;
margin: 0;
}
div:nth-of-type(2n) {
background: black;
}
div:after {
content: '';
position: absolute; top: 0; left: 0;
width: 100%;
height: 100%;
z-index: 2;
}
div:nth-of-type(2n):after {
background: red;
mix-blend-mode: multiply;
}
div:nth-of-type(2n + 1):after {
background: green;
mix-blend-mode: screen;
}
<h1>Scroll to see effect</h1>
<div></div>
<div></div>
<div></div>
I think the only way you could select the exact partial colors is using text or SVG paths.
Simple example with mix-blend-mode
:
html, body {
margin: 0;
}
h1 {
position: fixed; top: 0; left: 0;
width: 100vw;
text-align: center;
mix-blend-mode: difference;
color: white;
z-index: 1;
}
div {
width: 100vw;
height: 100vh;
background: black;
}
div:nth-of-type(2n) {
background: white;
}
<h1>Scroll to see effect</h1>
<div></div>
<div></div>
<div></div>
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