static isFrontFacing( a, b, c, direction ) {

		_v0$1.subVectors( c, b );
		_v1$3.subVectors( a, b );

		// strictly front facing
		return ( _v0$1.cross( _v1$3 ).dot( direction ) < 0 ) ? true : false;

	}
Returns `true` if the triangle is oriented towards the given direction.

@param {Vector3} a - The first corner of the triangle.
@param {Vector3} b - The second corner of the triangle.
@param {Vector3} c - The third corner of the triangle.
@param {Vector3} direction - The (normalized) direction vector.
@return {boolean} Whether the triangle is oriented towards the given direction or not.