 _preProcess( chain, pose, debug ){
        if( !this._points ) this._points = FabricUtil.createPointsFromChain( chain, true );   // JIT Array

        FabricUtil.setPointsFromBind( this._points, chain, pose, true );    // Set Positions
        this._effLinkIdx = chain.findByBoneIdx( this._effBoneIdx );         // Find Link Index
        vec3.copy( this._anchorPos, this._points[ 0 ].pos );                // initial position for anchoring
    }

}


// https://www.youtube.com/watch?v=wjn19jBzJCE
// https://g