Weird behavior of Spatial.look_at with translate in the same frame

Question

I posted an issue on GitHub since I think it's related to Godot itself rather than my own project since the math is standard and has worked for me in Unity and other engines.

Translating the node in the same frame as calling look_at in results in the object (maybe ?) being interpolated.

Github repo of reproducible project: https://github.com/iboshkov/GodotLookatDemo
Link to issue: https://github.com/godotengine/godot/issues/7277
Video: https://www.youtube.com/watch?v=wy1nhFdu7uc

Relevant code from the repo:

extends Spatial;

var dead_zone = Vector2(20, 20)
var screen_size

var speed = 5
var minion = null
var camera = null
var anim_player = null
var camera_pivot = null

func _input(ev):
    pass

func _process(delta):
    var pos = minion.get_translation ()
    var moveDir = Vector3(0, 0, 0)
    if Input.is_key_pressed(KEY_W):
        moveDir.z = 1
    elif Input.is_key_pressed(KEY_S):
        moveDir.z = -1
    if Input.is_key_pressed(KEY_A):
        moveDir.x = 1
    elif Input.is_key_pressed(KEY_D):
        moveDir.x = -1

    var a = pos
    var b = camera.get_global_transform().origin
    a.y = 0
    b.y = 0

    var forward = (a - b).normalized()
    var right = Vector3(forward.z, forward.y, -forward.x)
    var dir = moveDir.z * forward + moveDir.x * right
    dir.y = 0

    var offset = dir * speed * delta
    # Removing this line makes it rotate properly, but of course it's not what I need
    minion.global_translate(offset)
    minion.look_at(-forward, Vector3(0, 1, 0))

    camera_pivot.set_translation(minion.get_global_transform().origin)

func _ready():
    screen_size = get_viewport().get_rect().size
    minion = get_node("Actor")
    camera = get_node("Cam/Camera")
    camera_pivot = get_node("Cam")

    #anim_player = get_node("AnimationPlayer")
    #anim_player.play("Armature|Armature|Run|Armature|Run")
    set_process_input(true)
    set_process(true)

Comments

It looks like there is a mistake where you calculate your forward vector. I can take a look in some hours...

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What does not make sense to me is why it does work if I remove the translate line. If it sits in place it rotates just fine.

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Can you use this function to set your player's position and look at it at the same time? http://docs.godotengine.org/en/stable/classes/class_spatial.html#class-spatial-look-at-from-pos

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Same issue.

Here's the code I used with that method:

extends Spatial;

var speed = 5
var minion = null
var camera = null
var anim_player = null
var camera_pivot = null

func _input(ev):
    pass

func _process(delta):
    var pos = minion.get_global_transform().origin
    var moveDir = Vector3(0, 0, 0)
    if Input.is_key_pressed(KEY_W):
        moveDir.z = 1
    elif Input.is_key_pressed(KEY_S):
        moveDir.z = -1
    if Input.is_key_pressed(KEY_A):
        moveDir.x = 1
    elif Input.is_key_pressed(KEY_D):
        moveDir.x = -1

    var a = pos
    var b = camera.get_global_transform().origin
    a.y = 0
    b.y = 0
    var forward = (a - b).normalized()
    forward.y = pos.y
    var right = Vector3(forward.z, forward.y, -forward.x)
    forward.y = 0
    var dir = moveDir.z * forward + moveDir.x * right
    var offset = dir * speed * delta

    minion.look_at_from_pos(pos+offset, -forward, Vector3(0, 1, 0))

    camera_pivot.set_translation(minion.get_global_transform().origin)

func _ready():
    minion = get_node("Actor")
    camera = get_node("Cam/Camera")
    camera_pivot = get_node("Cam")

    set_process_input(true)
    set_process(true)

Answer 1

Okay so I seem to have misread the documentation. I thought look_at takes a directional vector as a parameter, but it's a position.