Bedrock animations

assets/<namespace>/ancientcreature/animations/<name>.animation.json

A standard Blockbench Bedrock Animation export.

{
  "format_version": "1.8.0",
  "animations": {
    "animation.triceratops.idle": {
      "animation_length": 4.0,
      "loop": true,
      "bones": {
        "body": {
          "rotation": {
            "0.0": [0, 0, 0],
            "1.0": { "post": [-0.8, 0, 0], "lerp_mode": "catmullrom" },
            "4.0": [0, 0, 0]
          },
          "position": { "0.0": [0, 0, 0], "2.0": [0, 0.32, 0] }
        }
      }
    }
  }
}

Naming

Name animations animation.<species>.<state>. The client entity's animations map gives each one a short name, and controllers and scripts.animate use the short name:

"animations": { "idle": "animation.triceratops.idle", "main": "controller.animation.triceratops.main" }

Supported

Feature	Notes
animation_length	Falls back to the last keyframe's time if omitted
start_delay, loop_delay	Molang, in seconds
anim_time_update	Molang deciding how query.anim_time advances, e.g. to play at walking speed
blend_weight	Molang weight for the whole animation
override_previous_animation	Replaces, rather than adds to, the pose of earlier animations
loop: true	Wraps forever
loop: false	Plays once, then stops contributing
loop: "hold_on_last_frame"	Plays once and holds the final pose
bones.<name>.rotation	Degrees
bones.<name>.position	Model units
bones.<name>.scale	Multiplier around 1
Scalar value	"0.0": 5 applies 5 to all three axes
Vector value	"0.0": [0, 5, 0]
Molang values	"0.0": ["math.sin(query.anim_time * 360) * 5", 0, 0], evaluated every frame
{ "pre": …, "post": … }	Different value approaching and leaving the keyframe — a step
lerp_mode: "linear"	Default
lerp_mode: "catmullrom"	Smooth spline through neighbouring keyframes
lerp_mode: "step"	Holds the value until the next keyframe
Constant channel	A channel written as one value instead of a keyframe map
relative_to: { "rotation": "entity" }	Rotation authored in entity space rather than the parent bone's
sound_effects	{ "time": { "effect": "name", "locator": "..." } }. Names map through the client entity's sound_effects
particle_effects	{ "time": { "effect": "name", "locator": "...", "pre_effect_script": "..." } }. Names map through the client entity's particle_effects
timeline	{ "time": "molang" } or a list of statements, run as playback passes each time

Animations are additive deltas over the model's rest pose, matching how Minecraft's own keyframe animations work. Multiple animations in one controller state stack.

Keyframes are sampled the way Blockbench's animator samples them, so playback in game matches its preview. Nothing is parsed while rendering.

Blending

When a controller changes state, the outgoing animation fades out while the incoming one fades in over the state's blend_transition seconds. Leave it out (or 0) for a hard cut.

Not supported

A keyframe with a non-numeric timestamp is skipped with a warning rather than failing the whole file.

Molang that does not compile is a load-time error naming the animation. See Molang for what the language supports.

Missing bones

If an animation targets a bone the geometry does not have, that channel is ignored and a warning is logged once naming the animation and the bone. The rest of the animation still plays — a renamed bone will not black-hole the whole creature.