How Can I Integrate Separate GLTF Animation Files Into a Single Three.js Model?

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Hello, I'm trying to combine multiple GLTF animations from different files onto one main GLTF model for my portfolio website. I have one file with a walk animation and another with an idle animation. I've tried several approaches including:

Creating separate mixers for each GLTF file and combining them
Using a shared skinned mesh, skeleton, and parent bone
Loading the gltf.scene from each file with an assetCount versus assetTotal check

Below is a snippet of my current code for loading the GLTF files and setting up the animations. (Note: the code is a bit messy due to previous testing.)

JAVASCRIPT
function spawnGeos(){
    
    // CHARACTER GEOS
    assetList.forEach(function(each){
        gltfLoader.load(
            each,
            (gltf) =>
            {
                geo = gltf.scene
                animationsWalk= gltf.animations
                
                // skeleton = new THREE.SkeletonHelper(geo)
                // skeleton.visible = false
                // scene.add( skeleton )
            
                geo.traverse((obj) => {
                    if(obj.isMesh){
                        const oldMat = obj.material
                        obj.material = new THREE.MeshStandardMaterial({
                            color:oldMat.color,
                            map:oldMat.map,
                            bumpMap:oldMat.bumpMap,
                            displacementMap:oldMat.displacementMap,
                            alphaMap:oldMat.alphaMap,
                            normalMap:oldMat.normalMap,
                            aoMap:oldMat.aoMap
                        })
                        obj.castShadow = true
                        obj.receiveShadow = true
                        //console.log(obj)
                    }
                })
                for(let i=0; i < 6; i++){
                    
                    geo.children[0].children[i].material.side = THREE.DoubleSide
                }
                
                //setupWalkAnimations()
            },
            () =>
            {
                console.log('progress')
            },
            () =>
            {
                console.log('error')
            });
    })
    
    gltfLoader.load(
        idleModel,
        (gltf) =>
        {
            idleAnim=gltf.scene
            idleAnim.visible = false
            let x=4
            idleAnim.scale.set(x,x,x)
            
            animationsIdle = gltf.animations
            //setupIdleAnimations()
            //checkProgress()
        },
        () =>
        {
            console.log('progress')
        },
        () =>
        {
            console.log('error')
        });
        
        checkProgress()
}

function checkProgress(){
    assetCount+=1
    console.log('assetCount:' + assetCount)
    console.log('assetTotal:' + assetTotal)
        
    if(assetCount == assetTotal-1){
        sharedAnimSetup()
        setupWalkAnimations()
        }
    if(assetCount == assetTotal){   
        setupIdleAnimations()
        displayData()}
    renderer.setAnimationLoop(animate)
}

// Additional functions: sharedAnimSetup, setupWalkAnimations, setupIdleAnimations, etc. follow below...

function sharedAnimSetup(){
    
    const identity = new THREE.Matrix4();
    let shareSkinnedMesh
    let sharedSkeleton
    let sharedParentBone
    shareSkinnedMesh = sharedModel.getObjectByName( 'IbernianWarrior_body' );
    sharedSkeleton = shareSkinnedMesh.skeleton;
    sharedParentBone = sharedModel.getObjectByName('JNT_pelvis')
    scene.add(sharedParentBone)
    let model1 = shareSkinnedMesh.clone();
    model1.bindMode = THREE.DetachedBindMode;
    
    model1.position.set(0,-.1,0)
    
    skeleton = new THREE.SkeletonHelper(sharedParentBone)
    skeleton.visible = false
    scene.add( skeleton )
    
    sharedParentBone.scale.set(x,x,x)
    
    model1.bind(sharedSkeleton, identity)
}

function setupWalkAnimations(){
    
    // WALK
    
    const mixerWalk = new THREE.AnimationMixer(model1)
    
    tPoseClip = THREE.AnimationUtils.subclip(animationsWalk[0],'All Animations', 1,49,60)
    tPoseAction = mixerWalk.clipAction(tPoseClip);
    
    walkClip = THREE.AnimationUtils.subclip(animationsWalk[0],'All Animations',50,149,60)
    walkAction = mixerWalk.clipAction(walkClip);
    
    actions.push(tPoseAction,walkAction)
    activateAllActions()
    scene.add(walkClone)
    
    mixers.push(mixerWalk)
}

function setupIdleAnimations(){
    // IDLE
    
    const idleClone = SkeletonUtils.clone(idleAnim);
    
    const mixerIdle = new THREE.AnimationMixer(idleClone)
    
    idleClip = THREE.AnimationUtils.subclip(animationsIdle[0],'All Animations',1,59,60)
    idleAction = mixerIdle.clipAction(idleClip);
    
    animSkel = new THREE.SkeletonHelper(idleAnim)
    animSkel.visible = false
    scene.add( animSkel )
    
    actions.push(idleAction)
    activateAllActions()
    scene.add(idleClone)
    mixers.push(mixerIdle)
}

I have experience with C#, C++, Unity, and Unreal Engine, but Three.js handles things differently. Any tips or guidance on how to properly integrate these separate animation files into one model would be greatly appreciated. Thank you in advance!

Comments 0

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Answers 1

•

1 Answer

Answer by StackOverflow TychoAI Agent • 9 days ago

Combining GLTF Animations from Different Files

To properly combine multiple GLTF animations from different files onto a single model in Three.js, you'll need to take a different approach than what you're currently using. Here's a recommended solution:

The Recommended Approach

The key to combining animations from different GLTF files is to:

Load your base model with its skeleton first
Load the animation data from other files
Apply all animations to a single AnimationMixer for the base model

Here's how you can implement this:

JAVASCRIPT
// First, define your model and animation paths
const modelPath = 'path/to/base/model.gltf';
const walkAnimationPath = 'path/to/walk/animation.gltf';
const idleAnimationPath = 'path/to/idle/animation.gltf';

// Create a single mixer that will be used for all animations
let mixer;
let model;
let animations = [];

// Load the base model first
gltfLoader.load(modelPath, (gltf) => {
    // Set up the model
    model = gltf.scene;
    scene.add(model);
    
    // Apply materials, shadows, etc.
    model.traverse((obj) => {
        if (obj.isMesh) {
            // Your material setup code here
            obj.castShadow = true;
            obj.receiveShadow = true;
        }
    });
    
    // Create a single mixer for the model
    mixer = new THREE.AnimationMixer(model);
    
    // Store any animations that came with the base model
    if (gltf.animations && gltf.animations.length) {
        gltf.animations.forEach(anim => {
            animations.push(anim);
        });
    }
    
    // Now load the walk animation
    loadWalkAnimation();
}, undefined, console.error);

function loadWalkAnimation() {
    gltfLoader.load(walkAnimationPath, (gltf) => {
        // Add the walk animations to our collection
        if (gltf.animations && gltf.animations.length) {
            gltf.animations.forEach(anim => {
                // Optionally rename the animation for clarity
                anim.name = 'walk';
                animations.push(anim);
            });
        }
        
        // Load the idle animation
        loadIdleAnimation();
    }, undefined, console.error);
}

function loadIdleAnimation() {
    gltfLoader.load(idleAnimationPath, (gltf) => {
        // Add the idle animations to our collection
        if (gltf.animations && gltf.animations.length) {
            gltf.animations.forEach(anim => {
                // Optionally rename the animation for clarity
                anim.name = 'idle';
                animations.push(anim);
            });
        }
        
        // Now that we have all animations, set them up
        setupAnimations();
    }, undefined, console.error);
}

function setupAnimations() {
    // Create actions for each animation
    const actions = {};
    
    animations.forEach(clip => {
        // You can use subclip here if needed
        // const subClip = THREE.AnimationUtils.subclip(clip, 'name', startFrame, endFrame, fps);
        const action = mixer.clipAction(clip);
        actions[clip.name] = action;
    });
    
    // Play the idle animation by default
    if (actions['idle']) {
        actions['idle'].play();
    }
    
    // Example of how to switch between animations
    // You can call these functions based on user input or other events
    function playWalkAnimation() {
        // Crossfade from current animation to walk
        const current = actions['idle'];
        const next = actions['walk'];
        
        current.fadeOut(0.5);
        next.reset().fadeIn(0.5).play();
    }
    
    function playIdleAnimation() {
        // Crossfade from current animation to idle
        const current = actions['walk'];
        const next = actions['idle'];
        
        current.fadeOut(0.5);
        next.reset().fadeIn(0.5).play();
    }
    
    // Make these functions available globally or through your app's interface
    window.playWalkAnimation = playWalkAnimation;
    window.playIdleAnimation = playIdleAnimation;
}

// Don't forget to update the mixer in your animation loop
function animate(time) {
    if (mixer) {
        mixer.update(clock.getDelta());
    }
    
    renderer.render(scene, camera);
    requestAnimationFrame(animate);
}

Key Points to Remember

Single Model, Single Mixer: Use only one model instance and one animation mixer.
Animation Compatibility: Make sure all your animation files have the same skeleton structure (bone names and hierarchy) as your base model.
Animation Blending: Use fadeIn/fadeOut methods to smoothly transition between animations.
Subclipping: If you need to extract specific parts of animations, use THREE.AnimationUtils.subclip() as you were doing.
Naming: Give your animations clear names to make them easier to reference.

If your animations still don't work correctly, it might be because the skeleton structure in your different GLTF files doesn't match. In that case, you might need to retarget the animations in a 3D modeling software before importing them into Three.js.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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