Give an app a springy entrance

Animate one application's windows with a small overshoot when they open, then shrink and fade them when they close. Replace the example app ID with the value reported by gnoblinctl window list --json.

gnoblin.animation {
    name = "spring-open",
    event = "open",
    duration = 340,
    ease = "ease-out-cubic",
    keyframes = {
        {at = 0, y = 22, scale = 0.9, opacity = 0},
        {at = 0.72, y = -4, scale = 1.025, opacity = 1},
        {at = 1, y = 0, scale = 1, opacity = 1},
    },
}

gnoblin.animation {
    name = "quick-close",
    event = "close",
    duration = 140,
    ease = "ease-in-quad",
    from = {scale = 1, opacity = 1},
    to = {scale = 0.88, opacity = 0},
}

gnoblin.window_rule {
    match = {type = "window", app_id = [[^org.gnome.TextEditor$]]},
    animation = {open = "spring-open", close = "quick-close"},
}

The middle keyframe grows slightly past full size, then settles. Only windows matching the rule use these animations; all other windows keep their current profiles. Change app_id to target another application.

Keyframe positions (at) run from 0 to 1; scale = 1 is the original size. See the animation guide and window-rule animation fields.