Difference of trigonometric function and directionvector

trigonometric function is just using in distance and directionvector is using in lookingside, isn't?

 

Trigonometric functions are functions for calculating. Player->getDirectionVector() returns the side to which player is looking.

PHP:

/**
     * @return Vector3
     */
    public function getDirectionVector() : Vector3{
        $y = -sin(deg2rad($this->pitch));
        $xz = cos(deg2rad($this->pitch));
        $x = -$xz * sin(deg2rad($this->yaw));
        $z = $xz * cos(deg2rad($this->yaw));

        return $this->temporalVector->setComponents($x, $y, $z)->normalize();
    }