Method parseSkeleton

packages/asset-system/src/loaders/GLTFLoader.ts:900–967

* Parse skeleton/skin data

(json: GLTFJson, buffers: ArrayBuffer[])

     * Parse skeleton/skin data
     */
    private parseSkeleton(json: GLTFJson, buffers: ArrayBuffer[]): ISkeletonData | undefined {
        if (!json.skins || json.skins.length === 0) return undefined;

        // Use first skin
        const skin = json.skins[0];
        const joints: ISkeletonJoint[] = [];

        // Load inverse bind matrices
        let inverseBindMatrices: Float32Array | null = null;
        if (skin.inverseBindMatrices !== undefined) {
            const ibmData = this.getAccessorData(json, buffers, skin.inverseBindMatrices);
            inverseBindMatrices = new Float32Array(ibmData.data.buffer, (ibmData.data as Float32Array).byteOffset, ibmData.count * 16);
        }

        // Build joint hierarchy
        const jointIndexMap = new Map<number, number>();
        for (let i = 0; i < skin.joints.length; i++) {
            jointIndexMap.set(skin.joints[i], i);
        }

        for (let i = 0; i < skin.joints.length; i++) {
            const nodeIndex = skin.joints[i];
            const node = json.nodes![nodeIndex];

            // Find parent
            let parentIndex = -1;
            for (const [idx, jointIdx] of jointIndexMap) {
                if (jointIdx !== i) {
                    const parentNode = json.nodes![idx];
                    if (parentNode.children?.includes(nodeIndex)) {
                        parentIndex = jointIdx;
                        break;
                    }
                }
            }

            const ibm = new Float32Array(16);
            if (inverseBindMatrices) {
                for (let j = 0; j < 16; j++) {
                    ibm[j] = inverseBindMatrices[i * 16 + j];
                }
            } else {
                // Identity matrix
                ibm[0] = ibm[5] = ibm[10] = ibm[15] = 1;
            }

            joints.push({
                name: node.name || `Joint_${i}`,
                nodeIndex,
                parentIndex,
                inverseBindMatrix: ibm
            });
        }

        // Find root joint
        let rootJointIndex = 0;
        for (let i = 0; i < joints.length; i++) {
            if (joints[i].parentIndex === -1) {