How to stop -0 in my transform.basis on slerp

Question

So I am trying to just rotate the camera/player 90 degrees (dungeon crawler style). I got it working but it would only turn once and get stuck in a loop. I found the -0 in the transform and have tried a few things but no luck

extends KinematicBody

var rotation_speed = .50
var targettransform 
var rotation_lerp = 0

func _ready():
    targettransform = self.transform.basis

func _process(delta):
    if self.transform.basis != targettransform: 
        rotate_player(delta)
        #not transform.basis.is_equal_approx(targettransform, 0.0001):
    if self.transform.basis == targettransform:
        rotation_lerp = 0
        get_input()
    print(transform.basis)
    print(targettransform)

func rotate_player(delta):
    if rotation_lerp < 1:
        rotation_lerp += delta * rotation_speed
    elif rotation_lerp > 1:
        rotation_lerp = 1
    transform.basis = transform.basis.slerp(targettransform , rotation_lerp).orthonormalized()

func get_input():
    if Input.is_action_just_pressed("turn_left"):
        print("left")
        targettransform = self.transform.basis.rotated(Vector3(0,1,0),1.5707963).orthonormalized()
        print (self.transform.basis.rotated(Vector3(0,1,0),1.5708))
    if Input.is_action_just_pressed("turn_right"):
        print("right")
        targettransform = self.transform.basis.rotated(Vector3(0,1,0),-1.5707963).orthonormalized()
        print (self.transform.basis.rotated(Vector3(0,1,0),-1.5708))

    if Input.is_action_just_pressed("Test_button"):
        print (transform.basis)
        print (targettransform)

Then I tried 0.0001 to 1 for the isequalapprox

func _process(delta):
    if not self.transform.basis.is_equal_approx(targettransform, 1):
        rotate_player(delta)
    if transform.basis.is_equal_approx(targettransform, 1):
        rotation_lerp = 0
        get_input()

Answer 1

Animations like that can be done using a Tween. Note that you may need to cancel and restart your Tween if the player turns again before the animation is done.

Answer 2

Since I couldn't out the way to do it with animation tween so I rotated the whole transform (instead of basis) and reset the origin so it did spin around world's origin.

extends KinematicBody

var rotation_speed = 7
var target_transform 
var rotation_lerp = 1
var party_state 
var FowardVector = 0
var old_location

func _ready():
    target_transform = self.transform
    old_location = self.transform
    party_state == "ready"


func _process(delta):
    if party_state == "ready":
        get_input()
    if not transform.is_equal_approx(target_transform):
        if party_state == "turning":
            rotate_party(delta)
        if party_state == "moving":
            pass
    if transform.is_equal_approx(target_transform):
        rotation_lerp = 1
        old_location = self.transform
        party_state = "ready"


func rotate_party(delta):
    if rotation_lerp < 75:
        rotation_lerp += delta * rotation_speed * rotation_lerp
    elif rotation_lerp > 75:
        rotation_lerp = 75
    self.transform = self.transform.interpolate_with(target_transform, rotation_lerp * delta)
    self.transform.origin = old_location.origin

func move_party():
    pass
#   #velocity = -transform.basis.z * speed
#   if transform.origin.distance_to(target) < .5:
#       target = null
#       velocity = Vector3.ZERO

func get_input():
    if Input.is_action_just_pressed("turn_left"):
        print("left")
        target_transform = target_transform.rotated(Vector3(0,1,0),1.5707963).orthonormalized()
        target_transform.origin = old_location.origin
        party_state = "turning"

    if Input.is_action_just_pressed("turn_right"):
        print("right")
        target_transform = target_transform.rotated(Vector3(0,1,0),-1.5707963).orthonormalized()
        target_transform.origin = old_location.origin
        party_state = "turning"