This tool has several different options for the fade in effect, as well as custom settings that can be applied to every selected div on the page, or even individually. The commented out section in the code has the different settings that can be over-ridden, and how to apply it individually. For example, you can set it to do it once, disable it on mobile, etc.
Fade effects include (they go in the direction mentioned): fade-up, fade-down, fade-left, fade-right, fade-up-right, fade-up-left, fade-down-right, fade-down-left, flip-up, flip-down, flip-left, flip-right, zoom-in, zoom-in-up, zoom-in-down, zoom-in-right, zoom-in-left, zoom-out, zoom-out-right, zoom-out-left, zoom-out-up, and zoom-out-down.
You don't have to copy the commented out code when you're using it, but if you want to change default setting, look through those settings.