Library of named easing curves and direction modifiers. All curves accept x in [0,1] and return [0,1] (with possible overshoot for ELASTIC/BACK/SPRING/BOUNCE). Curves are values you pass to setEase or compose via the IN/OUT/IN_OUT/PIECEWISE/BEZIER modifiers.

Library of named easing curves and direction modifiers. All curves accept x in [0,1] and return [0,1] (with possible overshoot for ELASTIC/BACK/SPRING/BOUNCE). Curves are values you pass to setEase or compose via the IN/OUT/IN_OUT/PIECEWISE/BEZIER modifiers.

Back ease-in: overshoots backward at the start before snapping forward.

Back ease-in: overshoots backward at the start before snapping forward.

Cubic Bezier curve solver in the style of CSS cubic-bezier. Control points (0,0), (x1,y1), (x2,y2), (1,1).

Cubic Bezier curve solver in the style of CSS cubic-bezier. Control points (0,0), (x1,y1), (x2,y2), (1,1).

Bouncing ease-in: slow ramp with bouncing impacts near the end. Symmetric with the other base curves, which are all ease-in. To get the classic "object falls and hits the ground" shape (bounces near x=1), wrap with Ease.OUT: Ease.OUT(Ease.BOUNCE).

Bouncing ease-in: slow ramp with bouncing impacts near the end. Symmetric with the other base curves, which are all ease-in. To get the classic "object falls and hits the ground" shape (bounces near x=1), wrap with Ease.OUT: Ease.OUT(Ease.BOUNCE).

Circular ease-in curve.

Circular ease-in curve.

Elastic ease-in: oscillates with decreasing amplitude.

Elastic ease-in: oscillates with decreasing amplitude.

Exponential ease-in curve (2^(10x-10)).

Exponential ease-in curve (2^(10x-10)).

Ease-in direction modifier: returns the curve unchanged. Symmetric with OUT and IN_OUT. Base curves are already ease-in by convention, so wrapping a curve in IN is a no-op — useful when picking the direction programmatically.

Ease-in direction modifier: returns the curve unchanged. Symmetric with OUT and IN_OUT. Base curves are already ease-in by convention, so wrapping a curve in IN is a no-op — useful when picking the direction programmatically.

Combine the first half of f with Ease.OUT(f) for a symmetric curve. Bug-fix vs the original library: the original referenced an undefined global Piecewise; this implementation routes through Ease.PIECEWISE.

Combine the first half of f with Ease.OUT(f) for a symmetric curve. Bug-fix vs the original library: the original referenced an undefined global Piecewise; this implementation routes through Ease.PIECEWISE.

Linear (identity) curve.

Linear (identity) curve.

Reverse a curve so it eases out instead of in: x => 1 - f(1 - x).

Reverse a curve so it eases out instead of in: x => 1 - f(1 - x).

Split [0,1] into N equal sections and run a different curve in each. Each curve is mapped to its section: section i runs over [i/n, (i+1)/n] and its output is mapped to [i/n, (i+1)/n] of the overall range.

Split [0,1] into N equal sections and run a different curve in each. Each curve is mapped to its section: section i runs over [i/n, (i+1)/n] and its output is mapped to [i/n, (i+1)/n] of the overall range.

Power curve factory: Ease.POWER(n) returns x => x**n. Use n=2 for quadratic, n=3 for cubic, etc.

Power curve factory: Ease.POWER(n) returns x => x**n. Use n=2 for quadratic, n=3 for cubic, etc.

Sine ease-in curve: starts slow, ends fast.

Sine ease-in curve: starts slow, ends fast.

Spring-like ease-out: oscillates outward after passing the target.

Spring-like ease-out: oscillates outward after passing the target.

Get how far this tween has progressed, from 0 (just started) to 1 (completed). Clamped — overshoot past completion still reads 1.

Get how far this tween has progressed, from 0 (just started) to 1 (completed). Clamped — overshoot past completion still reads 1.

Get the current interpolated value (the value most recently passed to the callback). Returns a number, Vector2, or Color depending on the tween's start/end types.

Get the current interpolated value (the value most recently passed to the callback). Returns a number, Vector2, or Color depending on the tween's start/end types.

Compute the interpolated value at the given remaining life. At life === duration the result is start; at life === 0 it is end.

Compute the interpolated value at the given remaining life. At life === duration the result is start; at life === 0 it is end.

True if this tween is in the active list and not paused.

True if this tween is in the active list and not paused.

Repeat this tween n total times. After each iteration finishes, a fresh tween with the same parameters takes over via the then slot. loop() with no argument loops forever.

Mutually exclusive with pingPong; calling either replaces the other, and calling then after either clears the loop (last call wins).

Repeat this tween n total times. After each iteration finishes, a fresh tween with the same parameters takes over via the then slot. loop() with no argument loops forever.

Mutually exclusive with pingPong; calling either replaces the other, and calling then after either clears the loop (last call wins).

Pause this tween. While paused, tweenUpdate skips it.

Pause this tween. While paused, tweenUpdate skips it.

Like loop, but swap start and end between iterations so the value bounces back and forth. pingPong() with no argument bounces forever.

Mutually exclusive with loop; calling either replaces the other, and calling then after either clears the loop (last call wins).

Like loop, but swap start and end between iterations so the value bounces back and forth. pingPong() with no argument bounces forever.

Mutually exclusive with loop; calling either replaces the other, and calling then after either clears the loop (last call wins).

Reset this tween to the start: life back to duration, pause cleared, re-added to the active list if previously stopped, and the callback re-fired with the start value.

Reset this tween to the start: life back to duration, pause cleared, re-added to the active list if previously stopped, and the callback re-fired with the start value.

Resume a paused tween.

Resume a paused tween.

Set the easing curve and return this for chaining.

Set the easing curve and return this for chaining.

Remove this tween from the active list and prevent any pending then-callback.

Remove this tween from the active list and prevent any pending then-callback.

Set a single completion callback. Calling then again replaces the previous callback. Returns this for chaining.

Calling then after loop or pingPong overrides the loop chain (last call wins).

Set a single completion callback. Calling then again replaces the previous callback. Returns this for chaining.

Calling then after loop or pingPong overrides the loop chain (last call wins).

Tween a property on an object by dot-path. Returns the underlying Tween so all chaining methods (setEase, then, loop, pingPong, etc.) remain available.

start and end may be numbers, Vector2 instances, Color instances, or any object with a lerp(other, percent) => sameType method.

Tween a property on an object by dot-path. Returns the underlying Tween so all chaining methods (setEase, then, loop, pingPong, etc.) remain available.

start and end may be numbers, Vector2 instances, Color instances, or any object with a lerp(other, percent) => sameType method.

Stop every active tween and clear their then-callbacks. Useful for resets on level transitions or when changing scenes.

Stop every active tween and clear their then-callbacks. Useful for resets on level transitions or when changing scenes.

Engine plugin hook: advance every active tween by the appropriate delta. Called once per render frame by the engine (no arguments). May also be called explicitly with (gameDelta, realDelta) to drive tweens manually — useful for headless tests or custom replay/scrubbing systems.

Engine plugin hook: advance every active tween by the appropriate delta. Called once per render frame by the engine (no arguments). May also be called explicitly with (gameDelta, realDelta) to drive tweens manually — useful for headless tests or custom replay/scrubbing systems.

Library of named easing curves and direction modifiers. All curves accept x in [0,1] and return [0,1] (with possible overshoot for ELASTIC/BACK/SPRING/BOUNCE). Curves are values you pass to setEase or compose via the IN/OUT/IN_OUT/PIECEWISE/BEZIER modifiers.

Library of named easing curves and direction modifiers. All curves accept x in [0,1] and return [0,1] (with possible overshoot for ELASTIC/BACK/SPRING/BOUNCE). Curves are values you pass to setEase or compose via the IN/OUT/IN_OUT/PIECEWISE/BEZIER modifiers.

Back ease-in: overshoots backward at the start before snapping forward.

Back ease-in: overshoots backward at the start before snapping forward.

Cubic Bezier curve solver in the style of CSS cubic-bezier. Control points (0,0), (x1,y1), (x2,y2), (1,1).

Cubic Bezier curve solver in the style of CSS cubic-bezier. Control points (0,0), (x1,y1), (x2,y2), (1,1).

Bouncing ease-in: slow ramp with bouncing impacts near the end. Symmetric with the other base curves, which are all ease-in. To get the classic "object falls and hits the ground" shape (bounces near x=1), wrap with Ease.OUT: Ease.OUT(Ease.BOUNCE).

Bouncing ease-in: slow ramp with bouncing impacts near the end. Symmetric with the other base curves, which are all ease-in. To get the classic "object falls and hits the ground" shape (bounces near x=1), wrap with Ease.OUT: Ease.OUT(Ease.BOUNCE).

Circular ease-in curve.

Circular ease-in curve.

Elastic ease-in: oscillates with decreasing amplitude.

Elastic ease-in: oscillates with decreasing amplitude.

Exponential ease-in curve (2^(10x-10)).

Exponential ease-in curve (2^(10x-10)).

Ease-in direction modifier: returns the curve unchanged. Symmetric with OUT and IN_OUT. Base curves are already ease-in by convention, so wrapping a curve in IN is a no-op — useful when picking the direction programmatically.

Ease-in direction modifier: returns the curve unchanged. Symmetric with OUT and IN_OUT. Base curves are already ease-in by convention, so wrapping a curve in IN is a no-op — useful when picking the direction programmatically.

Combine the first half of f with Ease.OUT(f) for a symmetric curve. Bug-fix vs the original library: the original referenced an undefined global Piecewise; this implementation routes through Ease.PIECEWISE.

Combine the first half of f with Ease.OUT(f) for a symmetric curve. Bug-fix vs the original library: the original referenced an undefined global Piecewise; this implementation routes through Ease.PIECEWISE.

Linear (identity) curve.

Linear (identity) curve.

Reverse a curve so it eases out instead of in: x => 1 - f(1 - x).

Reverse a curve so it eases out instead of in: x => 1 - f(1 - x).

Split [0,1] into N equal sections and run a different curve in each. Each curve is mapped to its section: section i runs over [i/n, (i+1)/n] and its output is mapped to [i/n, (i+1)/n] of the overall range.

Split [0,1] into N equal sections and run a different curve in each. Each curve is mapped to its section: section i runs over [i/n, (i+1)/n] and its output is mapped to [i/n, (i+1)/n] of the overall range.

Power curve factory: Ease.POWER(n) returns x => x**n. Use n=2 for quadratic, n=3 for cubic, etc.

Power curve factory: Ease.POWER(n) returns x => x**n. Use n=2 for quadratic, n=3 for cubic, etc.

Sine ease-in curve: starts slow, ends fast.

Sine ease-in curve: starts slow, ends fast.

Spring-like ease-out: oscillates outward after passing the target.

Spring-like ease-out: oscillates outward after passing the target.

Get how far this tween has progressed, from 0 (just started) to 1 (completed). Clamped — overshoot past completion still reads 1.

Get how far this tween has progressed, from 0 (just started) to 1 (completed). Clamped — overshoot past completion still reads 1.

Get the current interpolated value (the value most recently passed to the callback). Returns a number, Vector2, or Color depending on the tween's start/end types.

Get the current interpolated value (the value most recently passed to the callback). Returns a number, Vector2, or Color depending on the tween's start/end types.

Compute the interpolated value at the given remaining life. At life === duration the result is start; at life === 0 it is end.

Compute the interpolated value at the given remaining life. At life === duration the result is start; at life === 0 it is end.

True if this tween is in the active list and not paused.

True if this tween is in the active list and not paused.

Repeat this tween n total times. After each iteration finishes, a fresh tween with the same parameters takes over via the then slot. loop() with no argument loops forever.

Mutually exclusive with pingPong; calling either replaces the other, and calling then after either clears the loop (last call wins).

Repeat this tween n total times. After each iteration finishes, a fresh tween with the same parameters takes over via the then slot. loop() with no argument loops forever.

Mutually exclusive with pingPong; calling either replaces the other, and calling then after either clears the loop (last call wins).

Pause this tween. While paused, tweenUpdate skips it.

Pause this tween. While paused, tweenUpdate skips it.

Like loop, but swap start and end between iterations so the value bounces back and forth. pingPong() with no argument bounces forever.

Mutually exclusive with loop; calling either replaces the other, and calling then after either clears the loop (last call wins).

Like loop, but swap start and end between iterations so the value bounces back and forth. pingPong() with no argument bounces forever.

Mutually exclusive with loop; calling either replaces the other, and calling then after either clears the loop (last call wins).

Reset this tween to the start: life back to duration, pause cleared, re-added to the active list if previously stopped, and the callback re-fired with the start value.

Reset this tween to the start: life back to duration, pause cleared, re-added to the active list if previously stopped, and the callback re-fired with the start value.

Resume a paused tween.

Resume a paused tween.

Set the easing curve and return this for chaining.

Set the easing curve and return this for chaining.

Remove this tween from the active list and prevent any pending then-callback.

Remove this tween from the active list and prevent any pending then-callback.

Set a single completion callback. Calling then again replaces the previous callback. Returns this for chaining.

Calling then after loop or pingPong overrides the loop chain (last call wins).

Set a single completion callback. Calling then again replaces the previous callback. Returns this for chaining.

Calling then after loop or pingPong overrides the loop chain (last call wins).

Tween a property on an object by dot-path. Returns the underlying Tween so all chaining methods (setEase, then, loop, pingPong, etc.) remain available.

start and end may be numbers, Vector2 instances, Color instances, or any object with a lerp(other, percent) => sameType method.

Tween a property on an object by dot-path. Returns the underlying Tween so all chaining methods (setEase, then, loop, pingPong, etc.) remain available.

start and end may be numbers, Vector2 instances, Color instances, or any object with a lerp(other, percent) => sameType method.

Stop every active tween and clear their then-callbacks. Useful for resets on level transitions or when changing scenes.

Stop every active tween and clear their then-callbacks. Useful for resets on level transitions or when changing scenes.

Engine plugin hook: advance every active tween by the appropriate delta. Called once per render frame by the engine (no arguments). May also be called explicitly with (gameDelta, realDelta) to drive tweens manually — useful for headless tests or custom replay/scrubbing systems.

Engine plugin hook: advance every active tween by the appropriate delta. Called once per render frame by the engine (no arguments). May also be called explicitly with (gameDelta, realDelta) to drive tweens manually — useful for headless tests or custom replay/scrubbing systems.