Class AnimationPlayer

Example

//Transition between two Animation Clips `firstClipName` and `secondClipName`
//on tap by alternating secondClip weight between 0 or 1 within some `transitionInSec`,
//ensuring that secondClip is processed after firstClip as to blend the animations correctly.


//@input Component.AnimationPlayer animationPlayer
//@input number transitionInSec = 1
//@input string firstClipName
//@input string secondClipName

// Keep track of current state of transition.
let isTransitioning = false;
let accumulatedTime = 0;
let secondClipTargetWeight = 1;

// Store a reference to the clips so we don't
// have to keep asking engine.
let firstClip, secondClip;

// *********************************************************
// * Events that triggers and responds to the transitions.
// *********************************************************/

// Trigger the transition to the new clip.
const startTransition = script.createEvent("TapEvent");
startTransition.bind(triggerTransition);

const onUpdateEvent = script.createEvent("UpdateEvent");
onUpdateEvent.bind(interpolateBetweenAnimations);

// *********************************************************
// * Define how transitioning works.
// *********************************************************/

// Play the first clip immediately.
// and make sure clips are in the right order.
function init() {
    script.animationPlayer.playClipAt(script.firstClipName, 0);

    // Clips are processed in order. Thus, if we want to transition
    // to a second clip, we need to make sure the second clip
    // is processed after the first clip.
    putClipAtEndIfNeeded(script.animationPlayer, script.secondClipName);

    // Store references to the clips.
    firstClip = script.animationPlayer.getClip(script.firstClipName);
    secondClip = script.animationPlayer.getClip(script.secondClipName);
}

// Trigger the transition to the new clip.
function triggerTransition() {
    // Only transition, if we're not in the middle of transitioning.
    if (!isTransitioning) {
        // If the target weight is 0, that means the clip is already playing
        // so we don't need to tell it to play again.
        if (secondClipTargetWeight === 1) {
            script.animationPlayer.playClipAt(script.secondClipName, 0);
        }

        accumulatedTime = 0;
        isTransitioning = true;

        // Begin the update loop that will transition the clips.
        onUpdateEvent.enabled = isTransitioning;
    }
}

// Blend the weight of a second clip to the first clip,
// based on the time elapsed in transition.
function interpolateBetweenAnimations () {
    if (isTransitioning) {
        // Keep track of how many seconds elapsed since the start of the transition.
        accumulatedTime += getDeltaTime();

        // Once time has elapsed beyond our total transition time
        // we can finalize our weight and callback.
        if (accumulatedTime >= script.transitionInSec) {
            secondClip.weight = secondClipTargetWeight;

            onTransitionEnd();

            return;
        }

        // Set the current weight of the clips based on % between how long we've beeen transitioning for
        // and how long we want total transition to take.
        let currentWeight = accumulatedTime / script.transitionInSec ;
        secondClip.weight = lerp(1-secondClipTargetWeight, secondClipTargetWeight, currentWeight);
    }
}


function onTransitionEnd() {
    // Set our target weight to be the opposite.
    secondClipTargetWeight = 1 - secondClipTargetWeight;

    // Enable triggering transition, and disable the update loop.
    isTransitioning = false;
    onUpdateEvent.enabled = isTransitioning;
}

// *********************************************************
// * Helpers
// *********************************************************/

function putClipAtEndIfNeeded(animationPlayer, clipName) {
    const clips = animationPlayer.getAnimationClips();
    const currentOrderOfClips = clips.map(function(clip) {return clip.name;});
    const clipIndex = currentOrderOfClips.indexOf(clipName);

    if (clipIndex != clips.length - 1) {
        if (clipIndex < 0) {
            print("Clip with that name is not found in the provided Animation Player.");
            return;
        }

        const clonedClip = clips[clipIndex].clone(clipName);
        animationPlayer.removeClip(clipName);
        animationPlayer.addClip(clonedClip);
    }
}

function lerp(a, b, t) {
    return a * (1.0 - t) + b * t;
}

// *********************************************************
// * Initialize the script!
// *********************************************************/

init();
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