linkTimelines

Timelines control game behaviour and visuals based on a world clock through environment attributes. They define tracks that animate environment attributes over time using keyframes and easing functions. Optional named time markers act as labelled tick positions inside a timeline.

Timelines were added in snapshot 25w45a (Minecraft 1.21.11).

For a broader overview that covers world clocks, the /time command, and the timeCheck predicate condition together, see World Clocks.

linkBasic Usage

Every timeline must be bound to a WorldClockArgument. Register a clock first, then pass it when creating the timeline:

val dayClock = dataPack.worldClock("day")

val myTimeline = dataPack.timeline("day_fog", clock = dayClock) {
	periodTicks = 24000

	track(EnvironmentAttributes.Visual.FOG_START_DISTANCE) {
		ease = Linear

		keyframe(0) { value(0.0f) }
		keyframe(12000) { value(100.0f) }
	}
}

The timeline function creates and registers a timeline in your DataPack. It produces a file at data/<namespace>/timeline/<fileName>.json and returns a TimelineArgument.

linkTimeline Properties

linkTracks

Tracks map environment attributes to keyframe-based animations. Each track specifies an easing type, an optional modifier, and a list of keyframes.

dataPack.timeline("multi_track", clock = dayClock) {
	periodTicks = 24000

	track(EnvironmentAttributes.Visual.FOG_START_DISTANCE) {
		ease = Linear
		keyframe(0) { value(0.0f) }
		keyframe(12000) { value(100.0f) }
	}

	track(EnvironmentAttributes.Visual.FOG_END_DISTANCE) {
		ease = InOutCubic
		keyframe(0) { value(50.0f) }
		keyframe(6000) { value(200.0f) }
	}
}

linkTrack Properties

linkKeyframes

Each keyframe defines a value at a specific tick within the timeline period:

keyframe(0) {
	value(0.0f)
}

keyframe(12000) {
	value(100.0f)
}

The value function accepts Float, Int, Boolean, String, Color, or any EnvironmentAttributesType (e.g., FloatValue, BooleanValue, ColorValue).

Using typed values with EnvironmentAttributesType:

keyframe(0) {
	value(RGB(255, 128, 0))  // Color value
}

keyframe(12000) {
	value(FloatValue(1.0f))  // Explicit EnvironmentAttributesType
}

linkTime Markers

Time markers are named tick positions inside a timeline. Commands can jump a clock to a marker position via /time set <timeMarker>, and they appear in command auto-complete when showInCommands is true.

dataPack.timeline("seasons", clock = seasonClock) {
	periodTicks = 96000

	timeMarker("spring", ticks = 0, showInCommands = true)
	timeMarker("summer", ticks = 24000, showInCommands = true)
	timeMarker("autumn", ticks = 48000, showInCommands = true)
	timeMarker("winter", ticks = 72000, showInCommands = true)
}

Reference a marker in a function using TimeMarkerArgument:

function("skip_to_summer") {
	time.set(timeMarker("summer", "mymod"))
}

See World Clocks - Time Markers for the full command usage.

linkEasing Types

Easing types control how values are interpolated between keyframes.

linkNon-interpolating Types

linkInterpolating Types

Each interpolation kind is available in three forms: In*, Out*, and InOut*.

linkCubic Bezier

For custom easing curves, use CubicBezier with two control points:

dataPack.timeline("bezier_example", clock = dayClock) {
	periodTicks = 12000

	track(EnvironmentAttributes.Gameplay.SKY_LIGHT_LEVEL) {
		ease = CubicBezier(0.25f, 0.1f, 0.25f, 1.0f)

		keyframe(0) { value(0) }
		keyframe(6000) { value(15) }
	}
}

This serializes as:

{
  "ease": {
    "cubic_bezier": [
      0.25,
      0.1,
      0.25,
      1.0
    ]
  }
}

linkEnvironment Attributes

Tracks reference environment attributes from the EnvironmentAttributes sealed interface, organized into categories:

• EnvironmentAttributes.Audio - Sound-related attributes (ambient sounds, music volume, etc.)
• EnvironmentAttributes.Gameplay - Gameplay mechanics (monster burning, bed rules, sky light level, etc.)
• EnvironmentAttributes.Visual - Visual effects (fog, clouds, sky color, particles, etc.)

linkComplete Example

Here's a complete example of a day/night cycle timeline:

val dayClock = dataPack.worldClock("day")

dataPack.timeline("day_night_cycle", clock = dayClock) {
	periodTicks = 24000

	timeMarker("noon", ticks = 6000, showInCommands = true)
	timeMarker("midnight", ticks = 18000, showInCommands = true)

	track(EnvironmentAttributes.Visual.FOG_START_DISTANCE) {
		ease = InOutSine
		modifier = EnvironmentAttributeModifier.ADD

		keyframe(0) { value(10.0f) }
		keyframe(6000) { value(100.0f) }
		keyframe(12000) { value(100.0f) }
		keyframe(18000) { value(10.0f) }
	}

	track(EnvironmentAttributes.Gameplay.MONSTERS_BURN) {
		ease = Constant

		keyframe(0) { value(true) }
		keyframe(12000) { value(false) }
	}

	track(EnvironmentAttributes.Visual.SKY_LIGHT_FACTOR) {
		ease = CubicBezier(0.42f, 0.0f, 0.58f, 1.0f)

		keyframe(0) { value(1.0f) }
		keyframe(12000) { value(0.0f) }
	}
}

linkSee Also

• World Clocks - Clocks, time markers, the /time command, and timeCheck
• Environment Attributes - Environment attributes used in timeline tracks
• Tags - Use tags to group timelines

linkExternal Resources

• Minecraft Wiki: Timeline - Official JSON format reference