linkTimelines

Timelines control game behavior and visuals based on the absolute day time through environment attributes. They allow you to define tracks that animate environment attributes over time using keyframes and easing functions.

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

linkBasic Usage

Here's a simple example of creating a timeline that controls fog distance over a day cycle:

val myTimeline = timeline("day_fog") {
	periodTicks = 24000

	track(EnvironmentAttributes.Visual.FOG_START_DISTANCE) {
		ease = Linear
		modifier = "override"

		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.

timeline("multi_track") {
	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
}

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:

timeline("bezier_example") {
	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:

timeline("day_night_cycle") {
	periodTicks = 24000

	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

• Environment Attributes - Environment attributes used in timeline tracks
• Tags - Use tags to group timelines

linkExternal Resources

• Minecraft Wiki: Timeline - Official JSON format reference