static slerpFlat( dst, dstOffset, src0, srcOffset0, src1, srcOffset1, t ) {

		// fuzz-free, array-based Quaternion SLERP operation

		let x0 = src0[ srcOffset0 + 0 ],
			y0 = src0[ srcOffset0 + 1 ],
			z0 = src0[ srcOffset0 + 2 ],
			w0 = src0[ srcOffset0 + 3 ];

		const x1 = src1[ srcOffset1 + 0 ],
			y1 = src1[ srcOffset1 + 1 ],
			z1 = src1[ srcOffset1 + 2 ],
			w1 = src1[ srcOffset1 + 3 ];

		if ( t === 0 ) {

			dst[ dstOffset + 0 ] = x0;
			dst[ dstOffset + 1 ] = y0;
			dst[ dstOffset + 2 ] = z0;
			dst[ dstOffset + 3 ] = w0;
			return;

		}

		if ( t === 1 ) {

			dst[ dstOffset + 0 ] = x1;
			dst[ dstOffset + 1 ] = y1;
			dst[ dstOffset + 2 ] = z1;
			dst[ dstOffset + 3 ] = w1;
			return;

		}

		if ( w0 !== w1 || x0 !== x1 || y0 !== y1 || z0 !== z1 ) {

			let s = 1 - t;
			const cos = x0 * x1 + y0 * y1 + z0 * z1 + w0 * w1,
				dir = ( cos >= 0 ? 1 : -1 ),
				sqrSin = 1 - cos * cos;

			// Skip the Slerp for tiny steps to avoid numeric problems:
			if ( sqrSin > Number.EPSILON ) {

				const sin = Math.sqrt( sqrSin ),
					len = Math.atan2( sin, cos * dir );

				s = Math.sin( s * len ) / sin;
				t = Math.sin( t * len ) / sin;

			}

			const tDir = t * dir;

			x0 = x0 * s + x1 * tDir;
			y0 = y0 * s + y1 * tDir;
			z0 = z0 * s + z1 * tDir;
			w0 = w0 * s + w1 * tDir;

			// Normalize in case we just did a lerp:
			if ( s === 1 - t ) {

				const f = 1 / Math.sqrt( x0 * x0 + y0 * y0 + z0 * z0 + w0 * w0 );

				x0 *= f;
				y0 *= f;
				z0 *= f;
				w0 *= f;

			}

		}

		dst[ dstOffset ] = x0;
		dst[ dstOffset + 1 ] = y0;
		dst[ dstOffset + 2 ] = z0;
		dst[ dstOffset + 3 ] = w0;

	}
Interpolates between two quaternions via SLERP. This implementation assumes the
quaternion data are managed  in flat arrays.

@param {Array<number>} dst - The destination array.
@param {number} dstOffset - An offset into the destination array.
@param {Array<number>} src0 - The source array of the first quaternion.
@param {number} srcOffset0 - An offset into the first source array.
@param {Array<number>} src1 -  The source array of the second quaternion.
@param {number} srcOffset1 - An offset into the second source array.
@param {number} t - The interpolation factor in the range `[0,1]`.
@see {@link Quaternion#slerp}