 length
            bLen = ( step === 1 )? lnks[ iPrev ].len : lnks[ ii ].len;

            vec3.sub( dir, bpos[ ii ], bpos[ iPrev ] );                             // Direction from prev position to current
            vec3.normalize( dir, dir );                                             // Make it unit vector for scaling
            vec3.scaleAndAdd( bpos[ ii ], bpos[ iPrev ], dir, bLen );               // Scale direction then move away away from previous position

            iPrev = ii;                