getting_started/step_by_step/scripting_first_script

[giscus[bot]]

getting_started/step_by_step/scripting_first_script

In this lesson, you will code your first script to make the Godot icon turn in circles using GDScript. As we mentioned in the introduction, we assume you have programming foundations. The equivalen...

https://docs.godotengine.org/en/stable/getting_started/step_by_step/scripting_first_script.html

[mrwensveen]

It works but my animation was choppy at times. Disabling VSync worked for me, see: https://docs.godotengine.org/en/stable/tutorials/rendering/jitter_stutter.html

[addelian]

Can confirm that this worked for me as well, thanks @mrwensveen.

For others' reference, V-Sync can be turned off via CLI with --disable-vsync; otherwise, this can be changed manually by searching for "V-Sync" within Godot's Project Settings Project > Project Settings.

[CyrilDemand]

Hi, for the Hello World part in C#, it didn't work for me until I call GD.Print in a _Ready method.
public override void _Ready()
{
GD.Print("Hello, world!");
}

[InfieldTriple]

I personally found that sprite2d.gd script to be a bit unintuitive and it could use some changes. It might be due to my physics/math background. I've written a separate version of this script to separate the rotation (the image turning upside down) from the circular motion (motion of the centre of the axis around some central point).

extends Sprite2D

# circular motion angular speed
var angular_speed = PI/2

# rotation angular speed
var rotate_speed = 2*PI

# radius of rotation
var radius = 100

# Time vector
var mytime = 0


func _process(delta):

    # Time marches on
	mytime += delta

    # x (left/right) and y (up/down) speed
	var xvel = -radius * sin(2*PI*mytime/angular_speed)
	var yvel = radius * cos(2*PI*mytime/angular_speed)

    # Velocity vector
	var vel = xvel * Vector2.RIGHT + yvel * Vector2.UP 
	
	position += vel * delta
	rotation += rotate_speed * delta

This new version of the function allows you to set the motion dimensions more directly. The radius of the circular motion and the rotation and circular motion speeds separately.

I suspect there is a better way to do this in godot. I simply evaluated the derivative of the position vector of an object in circular motion my hand and hard coded it.

Something I think is missing from this doc (not sure if this qualifies for an issue to be raised) is an explanation of how sprite2d.gd works to rotate the sprite. Something like:

The sprite is forced in the direction Vector2.UP at speed speed. The position is changed by multiplying velocity by the time step delta, creating a new position vector and adding it to the previous position. The sprite follows a circular path by rotating the Vector2.UP vector using the Vector2.UP.rotated function where it supplies the variable rotation as an argument so that the vector Vector2.UP is rotated the exact same amount as the sprite. Then the sprite is given a velocity in that direction. Since at every time step this is adjusted, the sprite is moved forward slightly at this new angle resulting in circular motion.

I tried to decouple the rotation and circulation motion as follows by defining two angular_speed variables. This worked however, the radius still changes with angular_speed2 which makes sense physically but can be unintuitive. Thankfully, that only matters for anyone reading the code and not the player.

extends Sprite2D

var speed = 400
var angular_speed1 = PI
var angular_speed2 = 2*PI
var myrotation = 0

func _init():
	myrotation = rotation

func _process(delta):
	rotation += angular_speed1 * delta
	myrotation += angular_speed2 * delta
	var velocity = Vector2.UP.rotated(myrotation) * speed

	position += velocity * delta

[jsonjunkie]

i think you are over-thinking and over-complicating the sprite script. while it could be useful to have more control over how the icon moves and rotates, the extra bits of your scripts feel out of scope for this lesson

when you consider that every tick increases the rotation of the icon and that same rotation is applied to the velocity vector, the existing example might feel more intuitive

[pablomederos]

If you are new to C# programming, the Hello World code example

public MySprite2D()
{
    GD.Print("Hello, world!");
}

is placed in a constructor. Don't put it in the class body 'cause it won't work.

[DarthRevan39]

Hi, I had an issue with the icon displaying.

I was just running through this on Godot 4.3 and my Sprite2D was not set to be visible by default. Under the Inspector tab I had to go down to Visibility under CanvasItem and toggle visibility to on before I could see the Godot icon in the scene.

[Calinou]

If the sprite wasn't visible, it likely means you clicked on the eye icon besides it in the Scene tree dock at some point. Visible is true by default.

[DarthRevan39]

That is very possible! I didn't know that eye icon was there, but now I see it!

Thank you!