The update from 3.2.x to 3.3.x broke some of the solutions explained here and on other threads because of the change: "Added transforms to improve carousel performance in modern browsers."
If you are using Bootstrap 3.3.x there's a solution here:
http://codepen.io/transportedman/pen/NPWRGq
Basically you need to add the "carousel-fade" class to your carousel so that you have:
<div class="carousel slide carousel-fade">
And then include the following CSS:
/*
Bootstrap Carousel Fade Transition (for Bootstrap 3.3.x)
CSS from: http://codepen.io/transportedman/pen/NPWRGq
and: http://stackoverflow.com/questions/18548731/bootstrap-3-carousel-fading-to-new-slide-instead-of-sliding-to-new-slide
Inspired from: http://codepen.io/Rowno/pen/Afykb
*/
.carousel-fade .carousel-inner .item {
opacity: 0;
transition-property: opacity;
}
.carousel-fade .carousel-inner .active {
opacity: 1;
}
.carousel-fade .carousel-inner .active.left,
.carousel-fade .carousel-inner .active.right {
left: 0;
opacity: 0;
z-index: 1;
}
.carousel-fade .carousel-inner .next.left,
.carousel-fade .carousel-inner .prev.right {
opacity: 1;
}
.carousel-fade .carousel-control {
z-index: 2;
}
/*
WHAT IS NEW IN 3.3: "Added transforms to improve carousel performance in modern browsers."
Need to override the 3.3 new styles for modern browsers & apply opacity
*/
@media all and (transform-3d), (-webkit-transform-3d) {
.carousel-fade .carousel-inner > .item.next,
.carousel-fade .carousel-inner > .item.active.right {
opacity: 0;
-webkit-transform: translate3d(0, 0, 0);
transform: translate3d(0, 0, 0);
}
.carousel-fade .carousel-inner > .item.prev,
.carousel-fade .carousel-inner > .item.active.left {
opacity: 0;
-webkit-transform: translate3d(0, 0, 0);
transform: translate3d(0, 0, 0);
}
.carousel-fade .carousel-inner > .item.next.left,
.carousel-fade .carousel-inner > .item.prev.right,
.carousel-fade .carousel-inner > .item.active {
opacity: 1;
-webkit-transform: translate3d(0, 0, 0);
transform: translate3d(0, 0, 0);
}
}