Using keyframes to create cyclic animation - html

Question

I am working on a CSS only slider. However I don't have much experience with using keyframes.
I found this pen; could someone explain to me how the keyframes ensure that the animation runs in a cyclic manner rather than at the same time (where all the slides would disappear and reappear together)?
Code pen link
.slider {
max-width: 300px;
height: 200px;
margin: 20px auto;
position: relative;
}
.slide1,
.slide2,
.slide3,
.slide4,
.slide5 {
position: absolute;
width: 100%;
height: 100%;
}
.slide1 {
background: url(http://media.dunkedcdn.com/assets/prod/40946/580x0-9_cropped_1371566801_p17tbs0rrjqdt1u4dnk94fe4b63.jpg)no-repeat center;
background-size: cover;
animation: fade 8s infinite;
-webkit-animation: fade 8s infinite;
}
.slide2 {
background: url(http://media.dunkedcdn.com/assets/prod/40946/580x0-9_cropped_1371565525_p17tbqpu0d69c21hetd77dh483.jpeg)no-repeat center;
background-size: cover;
animation: fade2 8s infinite;
-webkit-animation: fade2 8s infinite;
}
.slide3 {
background: url(http://media.dunkedcdn.com/assets/prod/40946/580x0-9_cropped_1371564896_p17tbq6n86jdo3ishhta3fv1i3.jpg)no-repeat center;
background-size: cover;
animation: fade3 8s infinite;
-webkit-animation: fade3 8s infinite;
}
#keyframes fade {
0% {
opacity: 1
}
33.333% {
opacity: 0
}
66.666% {
opacity: 0
}
100% {
opacity: 1
}
}
#keyframes fade2 {
0% {
opacity: 0
}
33.333% {
opacity: 1
}
66.666% {
opacity: 0
}
100% {
opacity: 0
}
}
#keyframes fade3 {
0% {
opacity: 0
}
33.333% {
opacity: 0
}
66.666% {
opacity: 1
}
100% {
opacity: 0
}
}
<div class='slider'>
<div class='slide1'></div>
<div class='slide2'></div>
<div class='slide3'></div>
</div>

Answer 1

This is due to the each slide using a different keyframe, i.e. slide1 uses fade, slide2 uses fade2 and slide3 uses fade3. These keyframes all last 8 seconds however the frame in which the slide is shown is different:
slide1 is shown at 0% (0 seconds)
slide2 is shown at 33.333% (about 2.6 seconds)
slide3 is shown at 66.666% (about 5.3 seconds)
This particular method will work when you have three slides but would need to be adapted if you were to have a different amount. For example with four you would need to add an extra step to the keyframe:
.slider {
max-width: 300px;
height: 200px;
margin: 20px auto;
position: relative;
}
.slide1,
.slide2,
.slide3,
.slide4,
.slide5 {
position: absolute;
width: 100%;
height: 100%;
}
.slide1 {
background: url(http://media.dunkedcdn.com/assets/prod/40946/580x0-9_cropped_1371566801_p17tbs0rrjqdt1u4dnk94fe4b63.jpg)no-repeat center;
background-size: cover;
animation: fade 8s infinite;
-webkit-animation: fade 8s infinite;
}
.slide2 {
background: url(http://media.dunkedcdn.com/assets/prod/40946/580x0-9_cropped_1371565525_p17tbqpu0d69c21hetd77dh483.jpeg)no-repeat center;
background-size: cover;
animation: fade2 8s infinite;
-webkit-animation: fade2 8s infinite;
}
.slide3 {
background: url(http://media.dunkedcdn.com/assets/prod/40946/580x0-9_cropped_1371564896_p17tbq6n86jdo3ishhta3fv1i3.jpg)no-repeat center;
background-size: cover;
animation: fade3 8s infinite;
-webkit-animation: fade3 8s infinite;
}
.slide4 {
background: red;
background-size: cover;
animation: fade4 8s infinite;
-webkit-animation: fade4 8s infinite;
}
#keyframes fade {
0% {
opacity: 1
}
25% {
opacity: 0
}
50% {
opacity: 0
}
75% {
opacity: 0
}
100% {
opacity: 1
}
}
#keyframes fade2 {
0% {
opacity: 0
}
25% {
opacity: 1
}
50% {
opacity: 0
}
75% {
opacity: 0
}
100% {
opacity: 0
}
}
#keyframes fade3 {
0% {
opacity: 0
}
25% {
opacity: 0
}
50% {
opacity: 1
}
75% {
opacity: 0
}
100% {
opacity: 0
}
}
#keyframes fade4 {
0% {
opacity: 0
}
25% {
opacity: 0
}
50% {
opacity: 0
}
75% {
opacity: 1
}
100% {
opacity: 0
}
}
<div class='slider'>
<div class='slide1'></div>
<div class='slide2'></div>
<div class='slide3'></div>
<div class='slide4'></div>
</div>
As suggested by #ILoveCSS this code can be shortened to just the one keyframe animation by adding a third property to the animation property. This value is the animation-delay property and will stall the animation by the specified time:
.slider {
max-width: 300px;
height: 200px;
margin: 20px auto;
position: relative;
}
.slide1,.slide2,.slide3,.slide4,.slide5 {
position: absolute;
width: 100%;
height: 100%;
}
.slide1 {
background: url(http://media.dunkedcdn.com/assets/prod/40946/580x0-9_cropped_1371566801_p17tbs0rrjqdt1u4dnk94fe4b63.jpg)no-repeat center;
background-size: cover;
animation:fade 8s infinite;
-webkit-animation:fade 8s infinite;
}
.slide2 {
background: url(http://media.dunkedcdn.com/assets/prod/40946/580x0-9_cropped_1371565525_p17tbqpu0d69c21hetd77dh483.jpeg)no-repeat center;
background-size: cover;
animation:fade 8s infinite 2.6s;
-webkit-animation:fade 8s infinite 2.6s;
}
.slide3 {
background: url(http://media.dunkedcdn.com/assets/prod/40946/580x0-9_cropped_1371564896_p17tbq6n86jdo3ishhta3fv1i3.jpg)no-repeat center;
background-size: cover;
animation:fade 8s infinite 5.3s;
-webkit-animation:fade 8s infinite 5.3s;
}
#keyframes fade
{
0% {opacity:1}
33.333% { opacity: 0}
66.666% { opacity: 0}
100% { opacity: 1}
}
<div class='slider'>
<div class='slide3'></div>
<div class='slide2'></div>
<div class='slide1'></div>
</div>

Answer 2

I think what he is trying is:
#keyframes fade
{
0% {opacity:1}
33.333% { opacity: 0}
66.666% { opacity: 0}
100% { opacity: 1}
}
in this case slide1 is getting visible at the start of the animation and stops when it reached 33.333% and 66.666% and starts to visible at the end of the animation which is 100%.
#keyframes fade2
{
0% {opacity:0}
33.333% { opacity: 1}
66.666% { opacity: 0 }
100% { opacity: 0}
}
in the second slide2 at the start of the animation is not showing because slide1 is in the playing of it's animation and when slide1 reaches 33.333% started to stop and slide2 will start to fadeIn.
#keyframes fade3
{
0% {opacity:0}
33.333% { opacity: 0}
66.666% { opacity: 1}
100% { opacity: 0}
}
in the third slide3 the animation start to fadeIn at 66.666% because at this percent slide2 is in fadeOut state and it continue like this infinitely...
Hope you have an idea.