Tweens are useful for animations requiring a numerical property to be interpolated over a range of values. The name [i]tween[/i] comes from [i]in-betweening[/i], an animation technique where you specify [i]keyframes[/i] and the computer interpolates the frames that appear between them.
[Tween] is more suited than [AnimationPlayer] for animations where you don't know the final values in advance. For example, interpolating a dynamically-chosen camera zoom value is best done with a [Tween] node; it would be difficult to do the same thing with an [AnimationPlayer] node.
Here is a brief usage example that makes a 2D node move smoothly between two positions:
[codeblock]
var tween = get_node("Tween")
tween.interpolate_property($Node2D, "position",
Vector2(0, 0), Vector2(100, 100), 1,
Tween.TRANS_LINEAR, Tween.EASE_IN_OUT)
tween.start()
[/codeblock]
Many methods require a property name, such as [code]"position"[/code] above. You can find the correct property name by hovering over the property in the Inspector. You can also provide the components of a property directly by using [code]"property:component"[/code] (e.g. [code]position:x[/code]), where it would only apply to that particular component.
Many of the methods accept [code]trans_type[/code] and [code]ease_type[/code]. The first accepts an [enum TransitionType] constant, and refers to the way the timing of the animation is handled (see [url=https://easings.net/]easings.net[/url] for some examples). The second accepts an [enum EaseType] constant, and controls where the [code]trans_type[/code] is applied to the interpolation (in the beginning, the end, or both). If you don't know which transition and easing to pick, you can try different [enum TransitionType] constants with [constant EASE_IN_OUT], and use the one that looks best.
[url=https://raw.githubusercontent.com/godotengine/godot-docs/master/img/tween_cheatsheet.png]Tween easing and transition types cheatsheet[/url]
[b]Note:[/b] Tween methods will return [code]false[/code] if the requested operation cannot be completed.
Follows [code]property[/code] of [code]object[/code] and applies it on [code]target_property[/code] of [code]target[/code], beginning from [code]initial_val[/code] for [code]duration[/code] seconds, [code]delay[/code] seconds later.
Use [enum TransitionType] for [code]trans_type[/code] and [enum EaseType] for [code]ease_type[/code] parameters. These values control the timing and direction of the interpolation. See the class description for more information.
</description>
</method>
<methodname="get_runtime"qualifiers="const">
<returntype="float"/>
<description>
Returns the total time needed for all tweens to end. If you have two tweens, one lasting 10 seconds and the other 20 seconds, it would return 20 seconds, as by that time all tweens would have finished.
Calls [code]callback[/code] of [code]object[/code] after [code]duration[/code]. [code]arg1[/code]-[code]arg5[/code] are arguments to be passed to the callback.
Calls [code]callback[/code] of [code]object[/code] after [code]duration[/code] on the main thread (similar to [method Object.call_deferred]). [code]arg1[/code]-[code]arg5[/code] are arguments to be passed to the callback.
Animates [code]property[/code] of [code]object[/code] from [code]initial_val[/code] to [code]final_val[/code] for [code]duration[/code] seconds, [code]delay[/code] seconds later. Setting the initial value to [code]null[/code] uses the current value of the property.
Use [enum TransitionType] for [code]trans_type[/code] and [enum EaseType] for [code]ease_type[/code] parameters. These values control the timing and direction of the interpolation. See the class description for more information.
</description>
</method>
<methodname="is_active"qualifiers="const">
<returntype="bool"/>
<description>
Returns [code]true[/code] if any tweens are currently running.
[b]Note:[/b] This method doesn't consider tweens that have ended.
Resets a tween to its initial value (the one given, not the one before the tween), given its object and property/method pair. By default, all tweens are reset, unless [code]key[/code] is specified.
Animates [code]property[/code] of [code]object[/code] from the current value of the [code]initial_val[/code] property of [code]initial[/code] to [code]final_val[/code] for [code]duration[/code] seconds, [code]delay[/code] seconds later.
Use [enum TransitionType] for [code]trans_type[/code] and [enum EaseType] for [code]ease_type[/code] parameters. These values control the timing and direction of the interpolation. See the class description for more information.
The tween's speed multiplier. For example, set it to [code]1.0[/code] for normal speed, [code]2.0[/code] for two times normal speed, or [code]0.5[/code] for half of the normal speed. A value of [code]0[/code] pauses the animation, but see also [method set_active] or [method stop_all] for this.
