Эффект маски для изображений

<section class="project-1 cd-project-mask">
	<h1>Project Name</h1>
	<div class="featured-image"></div>
	<div class="mask">
		<img src="img/mask-01.png" alt="mask">
		<span class="mask-border mask-border-top"></span>
		<span class="mask-border mask-border-bottom"></span>
		<span class="mask-border mask-border-left"></span>
		<span class="mask-border mask-border-right"></span>
	</div>

	<a href="#0" class="project-trigger">Explore Project</a>

	<a href="#0" class="cd-scroll cd-img-replace">Scroll down</a>

	<div class="cd-project-info" data-url="project-1">
		<!-- content loaded using js -->
	</div>

	<a href="#0" class="project-close cd-img-replace">Close Project</a>
</section> <!-- .cd-project-mask -->

<section class="project-2 cd-project-mask">
	<!-- content here -->
</section>

<!-- other sections here -->

.cd-project-mask {
  position: relative;
  height: 100vh;
  width: 100%;
  overflow: hidden;
}

.cd-project-mask .featured-image {
    /* project intro image */
    position: absolute;
    left: 50%;
    top: 50%;
    bottom: auto;
    right: auto;
    transform: translateX(-50%) translateY(-50%);
  	height: 100%;
  	width: 100%;
  	background: url(../img/img-01.jpg) no-repeat center center;
  	background-size: cover;
}

.cd-project-mask .mask {
  position: absolute;
  left: 50%;
  top: 50%;
  bottom: auto;
  right: auto;
  transform: translateX(-50%) translateY(-50%);
  width: 300px;
  height: 300px;
}

.cd-project-mask .mask .mask-border {
  /* this is used to create a frame around the mask */
  position: absolute;
}

.cd-project-mask .mask .mask-border-top,
.cd-project-mask .mask .mask-border-bottom {
    /* this is used to create a frame around the mask */
    height: calc(50vh - 150px + 10px);
    width: 100vw;
    left: 50%;
    right: auto;
    transform: translateX(-50%);
}

.cd-project-mask .mask .mask-border-top {
    bottom: calc(100% - 10px);
}

.cd-project-mask .mask .mask-border-bottom {
    top: calc(100% - 10px);
}

.cd-project-mask .mask .mask-border-left,
.cd-project-mask .mask .mask-border-right {
  	/* this is used to create a frame around the mask */
	height: 100vh;
	width: calc(50vw - 150px + 10px);
	top: 50%;
	bottom: auto;
    transform: translateY(-50%);
}

.cd-project-mask .mask .mask-border-left {
  left: calc(100% - 10px);
}

.cd-project-mask .mask .mask-border-right {
  right: calc(100% - 10px);
}

.project-view .cd-project-mask:not(.project-selected) {
   /* the project-view class is added to the .cd-image-mask-effect element when a project is selected - hide all not selected projects */
   position: absolute;
   top: 0;
   left: 0;
   opacity: 0;
   visibility: hidden;
}

function ProjectMask( element ) {
	this.element = element;
	this.projectTrigger = this.element.find('.project-trigger');
	this.projectClose = this.element.find('.project-close');
	this.projectTitle = this.element.find('h1');
	this.projectMask = this.element.find('.mask');
	//...
	this.initProject();
}

var revealingProjects = $('.cd-project-mask');
var objProjectMasks = [];

if( revealingProjects.length > 0 ) {
	revealingProjects.each(function(){
		//create ProjectMask objects
		objProjectMasks.push(new ProjectMask($(this)));
	});
}

ProjectMask.prototype.initProject = function() {
	var self = this;

	//open the project
	this.projectTrigger.on('click', function(event){
		event.preventDefault();
		if( !self.animating ) {
			self.animating = true;
			//upload project content
			self.uploadContent();
			//show project content and scale up mask
			self.revealProject();
		}
	});

	//...
};

ProjectMask.prototype.revealProject = function() {
	var self = this;
	//get mask scale value
	self.updateMaskScale();
	//scale up mask and animate project title
	self.projectTitle.attr('style', 'opacity: 0;');
	self.projectMask.css('transform', 'translateX(-50%) translateY(-50%) scale('+self.maskScaleValue+')').one(transitionEnd, function(){
		self.element.addClass('center-title');
		self.projectTitle.attr('style', '');
		self.animating = false;
	});

	//hide the other sections
	self.element.addClass('project-selected content-visible').parent('.cd-image-mask-effect').addClass('project-view');
}

ProjectMask.prototype.uploadContent = function(){
	var self = this;
	//if content has not been loaded -> load it
	if( self.projectContent.find('.content-wrapper').length == 0 ) self.projectContent.load(self.projectContentUrl+'.html .cd-project-info > *');

	if( self.projectContentUrl+'.html'!=window.location ){
        //add the new page to the window.history
        window.history.pushState({path: self.projectContentUrl+'.html'},'',self.projectContentUrl+'.html');
    }
}