Fast input and smooth graphics

cybereality I'm only on the second page of the "getting started" guide. This is the entirety of the only script in the project:

using Godot;
using System;

public partial class sprite_2d : Sprite2D{
    private int Speed = 400;
    private float AngularSpeed = MathF.PI;

    public override void _Process(double delta){
        Input.UseAccumulatedInput = false;
        var direction = 0;
        
        if (Input.IsActionPressed("ui_left")){
            direction = -1;
            }
        if (Input.IsActionPressed("ui_right")){
            direction = 1;
        }
        Rotation += AngularSpeed * direction * (float)delta;

        var velocity = Vector2.Zero;
        if (Input.IsActionPressed("ui_up")){
            velocity = Vector2.Up.Rotated(Rotation) * Speed;
        }
        Position += velocity * (float)delta;
        }
}

It just moves the little built-in robot icon around, no physics or anything. I've also tried all three forms of vsync available.

cybereality
Thanks for all the help! I'm now trying this script instead:

using Godot;
using System;

public partial class sprite_2d : Sprite2D{
    private int Speed = 400;
    private float AngularSpeed = MathF.PI;
    private float direction = 0;
    private Vector2 velocity = Vector2.Zero;

    public override void _Input(InputEvent @event)
    {
        if (@event is InputEventKey keyEvent && keyEvent.Pressed){
            if (keyEvent.Keycode == Key.Left){
                direction -= 1;
            }
            if (keyEvent.Keycode == Key.Right){
                direction += 1;
            }
            if (keyEvent.Keycode == Key.Up){
                velocity = Vector2.Up.Rotated(Rotation) * Speed;
            }
        }
    }

    public override void _Process(double delta){
        Input.UseAccumulatedInput = false;
        
        Rotation += AngularSpeed * direction * (float)delta;
        direction = 0;
        
        Position += velocity * (float)delta;
        velocity = Vector2.Zero;
        }
}

I'm sure I'm just not understanding how to use the _Input event - there's little documentation on it, or at least it's difficult to find - but this has it's own set of problems: only one key input is registered at a time, and when you hold down a key it moves for one frame, then pauses for a couple frames, then continues moving smoothly, like when you hold down a key in a text editor. On top of that, there's still the same input delay, small but noticeable with vsync, gone but with occasionally choppy visuals without.

But if using the Input singleton causes a delay in player input (I was told the same thing on Reddit), why have it in the first place, and encourage it's use in official tutorials and documentation?

cybereality
I replaced it with this:

public override void _Input(InputEvent @event)
    {
        if (@event.IsAction("ui_left")){
            direction -= 1;
        }
        if (@event.IsAction("ui_right")){
            direction += 1;
        }
        if (@event.IsAction("ui_up")){
            velocity = Vector2.Up.Rotated(Rotation) * Speed;
        }
    }

and get the exact same results as with the last script I posted. If I use IsActionPressed instead of IsAction, it's the same thing except the icon only moves on the initial keypress, not when held down.

cybereality It's not major lag, as I said about 40ms, but it's enough to notice, especially if it were in a fast-paced action game.

I'd be surprised if it were my system - as I said, I don't see this kind of lag when using other engines, or when playing games made with them. It also goes away in Godot when I disable vsync, but again, that causes choppyness even when locking the game to 60fps and running the game in fullscreen (which again, I don't see in other engines).

cybereality Your project shows it exactly! And like in mine, the lag goes away if you turn off vsync in the project settings. Thanks for helping show I'm not crazy, at least.

I can think of lots of situations and styles of game where I'd prefer not to use physics and instead have pixel-perfect control over movement. Beyond that, even games that use physics for all movement would still have this lag when using special abilities, navigating menus, etc. This seems like a pretty egregious thing, and isn't present in 3.5. Is this maybe just the growing pains of 4.0, something that will likely be fixed soon, or is there somewhere I can report this as an issue to be fixed?

Reported. Thanks, everyone!