Molang (Geckolib4)

Molang is a power expression-based language that can be used to make complex and impressive animations. It does require surpassing a small learning curve to initially pick up, but once learned it becomes intuitive and a very useful tool.

What is it exactly?

Molang allows you to type directly write mathematical expressions into your animation keyframe, allowing you to dynamic animations with minimal effort. For example, instead of typing 20 into your keyframe animation value, you could type 5 * 4, which would automatically evaluate to 20.

That doesn't seem very useful at face value, but when you add in the ability to use mathematical functions and queries, it becomes much more powerful. For example, you could use the math.cos function to automatically calculate the cosine of a value: math.cos(5).

Or you can use queries, which are a way to retrieve in-game values as doubles for direct magic use in your expressions. For example, you could use the query.anim_time query to based your animation off the time in seconds the animation has been running: math.cos(query.anim_time) would cause your animation to automatically move back and forth smoothly, without any further effort

You can start to see from here where this is going. When you allow for both queries and functions, and full mathematical expression, it becomes obvious how powerful this can be, especially when you start to consider more complex expressions, E.G.

((-0.2 + 1.5 * (math.abs(math.mod(query.ground_speed, 13) - 6.5) - 3.25) / 3.25) * query.ground_speed) * 57.3

More info

You can read more information on Molang here. Note that GeckoLib's implementation of molang is slightly different to Microsoft's, in that some queries or functions may take slightly different arguments, or some may be added or missing.

Table of Contents

• Operators
• Functions
  • Custom Functions
• Queries
  • Custom Queries
• Compound Expressions
• Variables

Expressions

GeckoLib supports most basic logical and mathematical operators, as well as most standard queries and functions, which can be combined in any sensible way. See below for supported feature components in GeckoLib

Operators

Operators are expression symbols that represent an action to take in the expression

Operator	Function	Description
+	Addition	Adds two values together
-	Subtraction	Subtracts one value from another
*	Multiplication	Multiplies one value by another
/	Division	Divides one value by another
%	Modulus	Returns the modulo (remainder) when dividing one number by another
^	Exponent	Raise one value to the power of another
&&	Logical AND	Returns 1 if both conditions return a non-zero value, otherwise 0
||	Logical OR	Returns 1 if either condition returns a non-zero value, otherwise 0
!	Logical NOT	Returns 1 if the following value returns 0, otherwise 1
<	Less Than	Returns 1 if the left value is smaller than the right value, otherwise 0
<=	Less Than or Equal	Returns 1 if the left value is smaller than or equal to the right value, otherwise 0
>	Greater Than	Returns 1 if the left value is larger than the right value, otherwise 0
>=	Greater Than or Equal	Returns 1 if the left value is larger than or equal to the right value, otherwise 0
==	Equal	Returns 1 if the left value is equal to the right value, otherwise 0
!=	Not Equal	Returns 1 if the left value is not equal to the right value, otherwise 0
=	Variable Assignment	Sets a user-determined variable to the given value, for arbitrary use elsewhere
? :	Ternary	Evaluates the left expression. If a non-zero value given, return the middle expression, otherwise return the right expression
()	Brackets	Evaluates the expression inside the brackets before exposing it to outside expression conditions
;	Compound Expression Separator	Delimiter to split your expression into multiple expressions that run in order before returning the final expression's value. Typically used for variable assignments

Functions

Functions are expression components that allow provision of one or more numerical parameters, to generate a resultant value

Name	Function	Description	Parameters
math.abs	Absolute	Returns the absolute (non-negative) equivalent of the input value	input
math.acos	Arc-cosine	Returns the arc-cosine of the input value angle, with the input angle converted to radians	input (degrees)
math.asin	Arc-sine	Returns the arc-sine of the input value angle, with the input angle converted to radians	input (degrees)
math.atan	Arc-tangent	Returns the arc-tangent of the input value angle, with the input angle converted to radians	input (degrees)
math.atan2	Arc-tangent (theta)	Returns the arc-tangent theta of the input rectangular coordinate values (y,x), with the output converted to degrees	y, x
math.ceil	Ceiling	Returns the smallest value that is greater than or equal to the input value and is equal to an integer	input
math.clamp	Clamp	Returns the first input value if is larger than the second input value and less than the third input value; or else returns the nearest of the second two input values	value, min, max
math.cos	Cosine	Returns the cosine of the input value angle, with the input angle converted to radians	input (degrees)
math.die_roll	Dice Roll	Returns a random value determined by the sum of n random values generated within in a given range, optionally seeded	rolls, minroll, maxroll, seed (Optional)
math.die_roll_integer	Dice Roll (Integer)	Returns a random value determined by the sum of n random values generated within in a given range, optionally seeded, with the resultant value being an integer	rolls, minroll, maxroll, seed (Optional)
math.exp	Euler's Exponent	Returns euler's number raised to the power of the input value	input
math.floor	Floor	Returns the largest value that is less than or equal to the input value and is equal to an integer	input
math.hermite_blend	Hermite Interpolation	Returns the Hermite Polynomial (basis 3t^2 - 2t^3) curve interpolation value based on the input value	input
math.lerp	Linear-Interpolate	Returns the first value plus the difference between the first and second input values multiplied by the third input value	min, max, delta
math.lerprotate	Rotational Linear-Interpolation	Returns the first value plus the difference between the first and second input values multiplied by the third input value, wrapping the end result as a degrees value	min, max, delta
math.ln	Euler-Logarithmic	Returns the log value (euler base) of the input value	input
math.max	Max	Returns the greater of the two input values	inputA, inputB
math.min	Min	Returns the lesser of the two input values	inputA, inputB
math.mod	Modulus	Returns the remainder value of the input value when modulo'd by the modulus value	input, modulus
math.pi	PI	Returns PI (π)	None
math.pow	Exponent	Returns the input value raised to the power of the second input value	input, exponent
math.random	Random	Returns a random value between 0 and inputA, or betweeen inputA and inputB, optionally seeded	inputA, inputB (Optional), seed (Optional)
math.random_integer	Random Integer	Returns a random value between 0 and inputA, or betweeen inputA and inputB, optionally seeded, with the resultant value being an integer	inputA, inputB (Optional), seed (Optional)
math.round	Round	Returns the closest integer value to the input value	input
math.sin	Sine	Returns the sine of the input value angle, with the input angle converted to radians	input (degrees)
math.sqrt	Square-root	Returns the square root of the input value	input
math.to_deg	Radians-to-Degrees	Converts the input radians value to degrees	input (radians)
math.to_rad	Degrees-to-Radians	Converts the input degrees value to radians	input (degrees)
math.trunc	Truncate	Returns the closest value that is equal to the input value or closer to zero, and is equal to an integer	input

Custom Functions

GeckoLib supports users adding their own functions for use in Molang expressions. This is done via MathParser#registerFunction

Custom functions must be registered in your mod constructor

Queries

Queries are expression components that allow for in-code values to be provided to animations dynamically at runtime, allowing for expressions to take advantage of live data Note that some queries only apply to certain animatable types, and attempting to use them on an incompatible animatable will return 0 and error in the log.

All expressions below have their values automatically provided by GeckoLib

Name	Query	Description	Applies To
query.actor_count	Actor Count	Number of rendered entities in the last render pass	Global
query.anim_time	Animation Time	Time (in seconds) that the current animation has been running for	Any animatable
query.blocking	Blocking	Returns 1 if the entity is blocking, otherwise 0	LivingEntity
query.block_state	Blockstate Index	The index of the current blockstate variant	BlockEntity
query.body_x_rotation	X Body Rotation	The pitch rotation of the entity	Entity
query.body_y_rotation	Y Body Rotation	The yaw rotation of the entity	Entity
query.can_climb	Can Climb	Returns 1 if the entity doesn't have its AI disabled and uses WallClimberNavigation, otherwise 0	Mob
query.can_fly	Can Fly	Returns 1 if the entity doesn't have its AI disabled and uses FlyingPathNavigation, otherwise 0	Mob
query.can_swim	Can Swim	Returns 1 if the entity doesn't have its AI disabled and uses WaterBoundPathNavigation or AmphibiousPathNavigation, otherwise 0	Mob
query.can_walk	Can Walk	Returns 1 if the entity doesn't have its AI disabled and uses GroundPathNavigation or AmphibiousPathNavigation, otherwise 0	Mob
query.cardinal_facing	Entity Facing Direction	The direction the entity is facing, as an ordinal (0=Down, 1=Up, 2=North, 3=South, 4=West, 5=East)	Entity
query.cardinal_facing_2d	Entity Lateral Facing Direction	The direction the entity is facing, as an ordinal, ignoring vertical directions (2=North, 3=South, 4=West, 5=East, 6=Down, 6=Up)	Entity
query.cardinal_player_facing	Player Facing Direction	The direction the client player is facing, as an ordinal (0=Down, 1=Up, 2=North, 3=South, 4=West, 5=East)	Global
query.day	Day Number	The current day of the world, as a non-integer	Global
query.death_ticks	Death Time	Amount of time (in ticks) that the entity has been dead	LivingEntity
query.distance_from_camera	Distance From Camera	The distance in blocks the center of the entity is from the camera	Entity
query.equipment_count	Equipment Count	Number of worn items (not including items in mainhand or offhand)	LivingEntity
query.frame_alpha	Partial Tick	Returns the fraction of a tick that has passed since the last tick (partialtick)	Any animatable
query.get_actor_info_id	Entity ID	The numerical ID of the entity	Entity
query.ground_speed	Lateral Speed	The current lateral velocity of the entity in blocks/tick	LivingEntity
query.has_cape	Player Has Cape	Returns 1 if the client player has a cape, otherwise 0	Global
query.has_collision	Has Collision	Returns 1 if the entity has noclip enabled (no collisions), otherwise 0	Entity
query.has_gravity	Has Gravity	Returns 1 if the entity has gravity enabled, otherwise 0	Entity
query.has_head_gear	Has Headgear	Returns 1 if the entity is currently wearing something on its head, otherwise 0	LivingEntity
query.has_owner	Has Owner	Returns 1 if the entity is an OwnableEntity and has an owner, otherwise 0	Entity
query.has_player_rider	Has Player Passenger	Returns 1 if the entity has a passenger riding it that is a player, otherwise 0	Entity
query.has_rider	Has Passenger	Returns 1 if the entity has a passenger riding it, otherwise 0	Entity
query.head_x_rotation	X Head Rotation	The lerped pitch of the entity's head	LivingEntity
query.head_y_rotation	Y Head Rotation	The lerped yaw of the entity's head	LivingEntity
query.health	Health	The current health of the entity	LivingEntity
query.hurt_time	Hurt Time	Amount of time (in ticks) the entity has remaining on its hurt overlay	LivingEntity
query.invulnerable_ticks	Invulnerable Time	Amount of time (in ticks) the entity has remaining of invulnerability after taking damage	LivingEntity
query.is_alive	Is Alive	Returns 1 if the entity is alive, otherwise 0	Entity
query.is_angry	Is Angry	Returns 1 if the entity is a NeutralMob and is angry, otherwise 0	Entity
query.is_baby	Is Baby	Returns 1 if the entity is a baby, otherwise 0	LivingEntity
query.is_breathing	Is Breathing	Returns 1 if the entity has full air, otherwise 0	Entity
query.is_enchanted	Is Enchanted	Returns 1 if the itemstack has any enchantments, otherwise 0	Item
query.is_fire_immune	Is Fire Immune	Returns 1 if the entity's type is immune to fire, otherwise 0	Entity
query.is_first_person	Is in First Person	Returns 1 if the client player is in first person perspective, otherwise 0	Global
query.is_invisible	Is Invisible	Returns 1 if the entity is invisible, otherwise 0	Entity
query.is_in_contact_with_water	Is Contact With Water	Returns 1 if the entity is in water, rain, or a bubble column, otherwise 0	Entity
query.is_in_lava	In Lava	Returns 1 if the entity is in lava, otherwise 0	Entity
query.is_in_water	In Water	Returns 1 if the entity is in water, otherwise 0	Entity
query.is_in_water_or_rain	In Water Or Rain	Returns 1 if the entity is in water or rain, otherwise 0	Entity
query.is_leashed	Is Leashed	Returns 1 if the entity is Leashable and currently has a leash, otherwise 0	Entity
query.is_moving	Is Moving	Returns 1 if the entity is currently moving, otherwise 0	Entity
query.is_on_fire	Is On Fire	Returns 1 if the entity is on fire, otherwise 0	Entity
query.is_on_ground	Is On Ground	Returns 1 if the entity is on the ground, otherwise 0	Entity
query.is_powered	Is Powered	Returns 1 if the entity is a PowerableMob and is powered, otherwise 0	Entity
query.is_riding	Is Riding	Returns 1 if the entity is currently a passenger, otherwise 0	Entity
query.is_saddled	Is Saddled	Returns 1 if the entity is Saddleable and is saddled, otherwise 0	Entity
query.is_silent	Is Silent	Returns 1 if the entity is marked as silent, otherwise 0	Entity
query.is_sleeping	Is Sleeping	Returns 1 if the entity is sleeping, otherwise 0	LivingEntity
query.is_sneaking	Is Sneaking	Returns 1 if the entity is crouching, otherwise 0	Entity
query.is_sprinting	Is Sprinting	Returns 1 if the entity is sprinting, otherwise 0	Entity
query.is_stackable	Is Stackable	Returns 1 if the itemstack is stackable, otherwise 0	Item
query.is_swimming	Is Swimming	Returns 1 if the entity is swimming, otherwise 0	Entity
query.is_using_item	Is Using Item	Returns 1 if the entity is current using an item, otherwise 0	LivingEntity
query.is_wall_climbing	Is Wall Climbing	Returns 1 if the entity is currently on a climbable block, otherwise 0	LivingEntity
query.item_max_use_duration	Max Use Duration	The number of ticks the item can be used for at a maximum	Item
query.life_time	Rendering Time	The amount of time (in seconds) that the entity has been rendering for since the game started	Any animatable
query.main_hand_item_max_duration	Mainhand Item Max Duration	The number of ticks the entity's mainhand item can be used for at a maximum, or 0 if not holding an item	LivingEntity
query.main_hand_item_use_duration	Mainhand Item Use Duration	The number of ticks the entity's mainhand item has been in use, or 0 if not using an item	LivingEntity
query.max_durability	Max Durability	Returns the maximum durability of the itemstack	Item
query.max_health	Max Health	The max health of the entity	LivingEntity
query.moon_brightness	Moon Brightness	The brightness value of the moon's current phase, in 0.25 increments, with full moon as 1	Global
query.moon_phase	Moon Phase	The ordinal value of the moon's current phase (0->7 inclusive)	Global
query.movement_direction	Direction Moving	The direction ordinal closest to the entity's velocity (0=Down, 1=Up, 2=North, 3=South, 4=West, 5=East)	Entity
query.player_level	XP Level	The client player's current XP level	Global
query.remaining_durability	Remaining Durability	Returns the amount of durability remaining before breaking, or 1 if the item isn't breakable	Item
query.rider_body_x_rotation	Passenger X Body Rotation	The pitch of the entity's rider if it is a non-living entity, otherwise 0	Entity
query.rider_body_y_rotation	Passenger Y Body Rotation	The yaw of the entity's rider, otherwise 0	Entity
query.rider_head_x_rotation	Passenger X Head Rotation	The head pitch of the entity's rider if it is a LivingEntity, otherwise 0	Entity
query.rider_head_y_rotation	Passenger Y Head Rotation	The head yaw of the entity's rider if it is a LivingEntity otherwise 0	Entity
query.scale	Scale	The scale attribute value of the entity	LivingEntity
query.sleep_rotation	Sleep Rotation	The current Y rotation of the entity based on the bed it is sleeping in, or 0 if not sleeping	LivingEntity
query.time_of_day	Time of Day	The fraction of the day that the client player's level is currently in (0->1 inclusive)	Global
query.time_stamp	Game Time	The total tick count of the client player's world	Global
query.vertical_speed	Vertical Velocity	The entity's current vertical velocity	Entity
query.yaw_speed	Yaw Rotation Speed	The entity's current yaw rotation delta	Entity

Custom Queries

GeckoLib supports users adding their own queries for use in Molang expressions.

Query Name

Default GeckoLib variables are typically named query.variable_name.

When registering your own variable however, it's recommended that you name your variable to include your modid or something similar, to prevent clashes with other mods also registering variables

E.G. query.mymod_variable_name

Standard Variable

Registering your custom variable only requires a single line of code, put in your mod's constructor, or client entrypoint.

To do this, we use the MolangQueries#setActorVariable method.

This takes a generic (which should be your animatable's base type), the query name, and a function that returns the variables value.

E.G.

MolangQueries.<MyAnimatable>setActorVariable("query.mymod_entity_bouncing", actor -> actor.animatable.getBouncing());

This registers a variable called "query.mymod_entity_bouncing" for an animatable of type MyAnimatable, using the MyAnimatable#getBouncing method to determine its value

Multi-type Variable

If your variable is used across multiple types of animatables, and they can't share a parent class that provides the value, then you will need to register a generic variable instead.

This is done via MathParser#registerVariable, using a default value of 0.

E.G. MathParser.registerVariable(new Variable("query.mymod_entity_bouncing", 0))

Custom queries must be registered in your mod constructor, and you do not need to keep the Variable instance you create here if you don't want to, since it'll be automatically retrieved later when setting the value.

Once you have registered your query, you must provide its value during runtime, via overriding GeoModel#applyMolangQueries in the relevant model, and setting the value via MathParser#setVariable

setVariable takes the same query name as your registered variable, and a supplier of the value the query should be, E.G. MathParser.setVariable("query.mymod_entity_bouncing", () -> myEntity.getBouncing())

Compound Expressions

Compound expressions are a Molang feature that allows you to evaluate multiple expressions in a single animation keyframe. This is mostly useful for setting and getting variable whilst still returning an animation value.

To perform compound expressions, split your expressions with the ; delimiter. Each split will be evaluated as its own expression in order, with the last expression returning the value for the animation.

E.G. v.is_animating_walk = 1;math.sin(query.anim_time)

This will result in a 2-part compound expression with the first part setting a local variable is_animating_walk to 1, and then returning math.sin(query.anim_time) from the expression

Variables

Variables are an expression component that allow you to store arbitrary data from within an expression, to retrieve it in a further animation or keyframe. This is useful in compound expressions, where you may need to evaluate some data in sequence before utilising it, or for otherwise temporarily storing data.

Note that variables are global in GeckoLib, so any variable you store will be shared with all other animatables using the same variable. Keep this in mind when designing your variable usage, either using unique names, or by only using the variables within the same animation frame pass.