Forward + and Mobile renderers cause jitter in player position movement over time on machine with 1070 ti

[jrdoughty]

Tested versions

Reproducable in in latest 4.3 and 4.2.1

System information

Windows 11, Ryzen 5 5500, GTX 1070 Ti. Driver 551.61

Issue description

My son's player character was built following this tutorial: https://www.youtube.com/watch?v=KceMokK2qFA

On his computer the character/camera will seem to lag for a frame, then for a couple frames, and eventually vibrate the screen as the character moves. When printing the X position, we were able to see that as far as the game was concerned, the player always moved consistently. We then detatched the camera from the player to see if it was a camera issue. When we did this, the player would be the only thing to begin to vibrate (again, progressively worse as the game ran).

My friend and I pulled the code up on our own machines, and low and behold we didn't see the issue. I went back to my son's machine and after several tests (including the latest Godot dev build), finally started changing renderers. We found the compatibility renderer resolved the issue. The only major difference between my son and I's machine is our graphics cards. His is a Ryzen 5 5500 cpu with 16gb ram and a 1070ti, mine is a 5800x3d, 16gb ram, with an rx 6600.
Character Script:

extends CharacterBody2D

@export var MAX_SPEED = 30
@export var axis = Vector2.ZERO
@export var FRICTION = 1200
@export var ACCELERATION = 500
@export var HUNGER = 100
@export var MAX_HUNGER = 100
func _physics_process(delta):
	move_and_slide()
		
func _process(delta):
	if HUNGER > 100:
		HUNGER = 100
		
	if Input.is_action_just_pressed("attack"):
		$AnimationAttackPlayer.play("hit")
	
	
	move(delta)	
	
	
func get_input_axis():
	axis.y = int(Input.is_action_pressed("ui_down")) - int(Input.is_action_pressed("ui_up"))
	axis.x = int(Input.is_action_pressed("ui_right")) - int(Input.is_action_pressed("ui_left"))
	return axis.normalized()

func move(delta):
	get_input_axis()
		
	if axis==Vector2.ZERO:
		apply_friction(FRICTION * delta)
	else:
		apply_movement(axis * ACCELERATION)
func apply_friction(amount):
	if velocity.length() > amount:
		velocity -= velocity.normalized() * amount
	else:
		velocity = Vector2.ZERO
		
		
func apply_movement(accel):
	velocity += accel
	velocity = velocity.limit_length(MAX_SPEED)

Character Scene:

[gd_scene load_steps=13 format=3 uid="uid://ck07ddw077t14"]

[ext_resource type="Texture2D" uid="uid://dvwqmt5gam3s2" path="res://player stuff/yinou sheet.png" id="1"]
[ext_resource type="Script" path="res://player stuff/Yinou.gd" id="2"]
[ext_resource type="Texture2D" uid="uid://bm7leb73ong83" path="res://heart.png" id="3_hul3j"]
[ext_resource type="Texture2D" uid="uid://cinh8dwww5bpx" path="res://apple.png" id="4_iwnrh"]
[ext_resource type="Texture2D" uid="uid://b8lfyn1almnvc" path="res://attack.png" id="5_3la2l"]

[sub_resource type="Animation" id="1"]
resource_name = "norm"
tracks/0/type = "value"
tracks/0/imported = false
tracks/0/enabled = true
tracks/0/path = NodePath("CharacterBody2D/YinouSheet:frame")
tracks/0/interp = 1
tracks/0/loop_wrap = true
tracks/0/keys = {
"times": PackedFloat32Array(0),
"transitions": PackedFloat32Array(1),
"update": 0,
"values": [0]
}

[sub_resource type="Animation" id="2"]
resource_name = "up"
tracks/0/type = "value"
tracks/0/imported = false
tracks/0/enabled = true
tracks/0/path = NodePath("CharacterBody2D/YinouSheet:frame")
tracks/0/interp = 1
tracks/0/loop_wrap = true
tracks/0/keys = {
"times": PackedFloat32Array(0),
"transitions": PackedFloat32Array(1),
"update": 0,
"values": [1]
}

[sub_resource type="AnimationLibrary" id="AnimationLibrary_c26su"]
_data = {
"norm": SubResource("1"),
"up": SubResource("2")
}

[sub_resource type="Animation" id="Animation_n0c7b"]
resource_name = "hit"
length = 1.1
tracks/0/type = "value"
tracks/0/imported = false
tracks/0/enabled = true
tracks/0/path = NodePath("CharacterBody2D/AttackCollider/Attack:frame")
tracks/0/interp = 1
tracks/0/loop_wrap = true
tracks/0/keys = {
"times": PackedFloat32Array(0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1),
"transitions": PackedFloat32Array(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1),
"update": 1,
"values": [10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10]
}
tracks/1/type = "value"
tracks/1/imported = false
tracks/1/enabled = true
tracks/1/path = NodePath("CharacterBody2D/AttackCollider:disabled")
tracks/1/interp = 1
tracks/1/loop_wrap = true
tracks/1/keys = {
"times": PackedFloat32Array(0.1, 0.3, 0.8),
"transitions": PackedFloat32Array(1, 1, 1),
"update": 1,
"values": [true, false, true]
}

[sub_resource type="AnimationLibrary" id="AnimationLibrary_w417y"]
_data = {
"hit": SubResource("Animation_n0c7b")
}

[sub_resource type="RectangleShape2D" id="RectangleShape2D_rwii4"]
size = Vector2(19.6201, 20.2144)

[sub_resource type="RectangleShape2D" id="RectangleShape2D_e8mm3"]
size = Vector2(14.8687, 17.2418)

[node name="Player" type="Node2D"]
texture_filter = 1
scale = Vector2(0.363822, 0.349291)

[node name="CharacterBody2D" type="CharacterBody2D" parent="." groups=["Player"]]
scale = Vector2(1, 1.186)
collision_layer = 5
script = ExtResource("2")

[node name="YinouSheet" type="Sprite2D" parent="CharacterBody2D"]
texture_filter = 1
position = Vector2(2.25702, -1.55343)
texture = ExtResource("1")
hframes = 2

[node name="AnimationPlayer" type="AnimationPlayer" parent="CharacterBody2D"]
root_node = NodePath("../..")
libraries = {
"": SubResource("AnimationLibrary_c26su")
}

[node name="AnimationAttackPlayer" type="AnimationPlayer" parent="CharacterBody2D"]
root_node = NodePath("../..")
libraries = {
"": SubResource("AnimationLibrary_w417y")
}

[node name="CollisionShape2D" type="CollisionShape2D" parent="CharacterBody2D"]
position = Vector2(0.692766, 1.87747)
scale = Vector2(1, 1.77246)
shape = SubResource("RectangleShape2D_rwii4")
debug_color = Color(0.996078, 0, 0.152941, 0.419608)

[node name="AttackCollider" type="CollisionShape2D" parent="CharacterBody2D" groups=["attack"]]
position = Vector2(21.989, 2.414)
shape = SubResource("RectangleShape2D_e8mm3")
disabled = true
debug_color = Color(0.423529, 0.603922, 0, 0.419608)

[node name="Attack" type="Sprite2D" parent="CharacterBody2D/AttackCollider"]
position = Vector2(-5.4972, 2.41394)
rotation = 3.14159
scale = Vector2(0.869056, -0.84317)
texture = ExtResource("5_3la2l")
hframes = 11
frame = 10

[node name="Camera2D" type="Camera2D" parent="CharacterBody2D"]
scale = Vector2(1, 1)
zoom = Vector2(10, 10)

[node name="ProgressBar" type="ProgressBar" parent="CharacterBody2D/Camera2D"]
modulate = Color(0.141176, 1, 0.466667, 1)
self_modulate = Color(0.780392, 0.780392, 0.780392, 1)
offset_left = -153.921
offset_top = -74.8324
offset_right = -82.9214
offset_bottom = -47.8324
scale = Vector2(1.0073, 0.684069)
value = 100.0

[node name="Heart" type="Sprite2D" parent="CharacterBody2D/Camera2D/ProgressBar"]
texture_filter = 1
position = Vector2(62.7593, 14.1152)
scale = Vector2(0.674541, 0.882202)
texture = ExtResource("3_hul3j")

[node name="ProgressBar2" type="ProgressBar" parent="CharacterBody2D/Camera2D"]
modulate = Color(0.960784, 0.247059, 0, 1)
self_modulate = Color(0.780392, 0.780392, 0.780392, 1)
offset_left = -153.921
offset_top = -53.1069
offset_right = -82.9214
offset_bottom = -26.1069
scale = Vector2(1.0073, 0.684069)
value = 100.0

[node name="Apple" type="Sprite2D" parent="CharacterBody2D/Camera2D/ProgressBar2"]
texture_filter = 1
position = Vector2(62.7593, 14.1152)
scale = Vector2(0.496374, 0.61629)
texture = ExtResource("4_iwnrh")

Steps to reproduce

run game project
press 'Play' menu button
wait about 10-15 sec and notice that any movement of the player from the arrow keys causes jitters if your Graphics card is affected.

Minimal reproduction project (MRP)

https://github.com/VinDoughty/CrumbledMap2

[AThousandShips]

Does it work correctly if you only update velocity in _physics_process?

[jrdoughty]

Apologies, forgot to check this on my son's machine before he went to bed. I'll try to run it tomorrow.

[JustKwa]

I also ran into this exact same problem where the character vibrate when moving around with the camera node attached to them on my desktop. However, when I ran it on my laptop, everything seems to be working as intended. I have a rx 580 and a ryzen 5 3500.

[jrdoughty]

No difference after moving it all within physics process

[jrdoughty]

https://technical.city/en/video/GeForce-GTX-1070-Ti-vs-Radeon-RX-580 According to this, 1070ti and rx580 have some similar graphics support, so could be same issue?

[Calinou]

I can't reproduce this on 4.3.dev 9b94c80 (Linux, GeForce RTX 4090 with NVIDIA 545.29.06). Even when running the project with --time-scale 20 and waiting several minutes, I don't notice any vibration when I move the player.

Are you sure this isn't jitter due to frameskips or a lack of physics interpolation?

Are you using a multi-monitor setup on the affected systems, specifically with different refresh rates on each monitor? This is bound to cause issues with smoothness in general, even in apps outside of Godot. Physics interpolation can help with this to an extent, but there's only so much it can do.

[jrdoughty]

It is multi monitor, but I don't know how likely that is to be the cause, particularly since the compatibility renderer works. My machine is also multi monitor with different refresh rates. I'll try to test it tomorrow be sure though, as I've heard of stranger things.

As for frame skips or physics interpolation, I know for sure there are no frame skips. The lack of interpolation is a hard maybe, but as you can see from that video and you and my testing it certainly doesn't cause an issue on other hardware.

[jrdoughty]

Hopefully I'll have my own test system here in a bit so I can test after kids crash... but might be a week or more

[jrdoughty]

Going to a single display didn't have any effect