Noob asking

Danilo

Hello all, I hope someone can help. I started using Godot few days ago and I'm struggling with basic GDsript stuff. Is this the right place to ask that kind of questions?

If so here is mine: I want to make simple car like user controlled object that rotates and moves in the new facing direction. here is my script so far but it dont works... I tried to use normalized() somehow but I still don't get it. Many thanks

extends KinematicBody

var speed = 4
var velocity = Vector3()


func _physics_process(delta):
	control(delta)
	velocity = move_and_slide(velocity)

func control(delta):
	velocity.x = 0
	velocity.z = 0
		
	if Input.is_action_pressed("ui_up"):
		velocity.z. -= speed
		velocity = velocity.normalized()
	if Input.is_action_pressed("ui_down"):
		velocity.z += speed
	if Input.is_action_pressed("ui_right"):
		rotation.y -= 0.01
	if Input.is_action_pressed("ui_left"):
		rotation.y += 0.01

Megalomaniak

You aren't modulating any of your values/variables by delta, also, those rotation values are rather small so it might just take a very long time to turn maybe?

Danilo

Hi, thanks for the reply! The rotation is working fine but "ui_up" just goes straight on z axis .. I think somehow that axis should be changed in basis of the new direction.

I put delta, as I saw other do, but it doesnt change anything , if its there or not.

TwistedTwigleg

Change lines 15 through 19 to the following:

if Input.is_action_pressed("ui_up"):
	var forward_direction = Vector2(cos(rotation), sin(rotation))
	velocity -= forward_direction * speed * delta
if Input.is_action_pressed("ui_down"):
	var forward_direction = Vector2(cos(rotation), sin(rotation))
	velocity += forward_direction * speed * delta

I have not tested the code, but I think it should work.

What this does is that it takes the rotation and converts it into a position around the unit circle. This GIF shows an example of what is happening:

https://media.giphy.com/media/fzRG2T0jDujcI/giphy.gif

In the GIF above, rotation is the angle and the point on the green circle is what we are storing in the forward_direction variable.

By multiplying by speed and delta, we are basically changing the magnitude/length of the unit circle position. We can then add/subtract this position to velocity, and that will should move it in the correct direction. :smile:

I probably explained how it works poorly. My brain is working on autopilot right now :sweat_smile: Hopefully the code above helps a bit! (Side note: Welcome to the forums)

Danilo

Hi, thanks again for the help. I kinda understand vaguely the concept, although my scene is in 3D space, so not sure if Vector2 can work there? Will try to implement it somehow anyway.

--EDIT: I found the solution: Just needed to make it work in the local space cordinates

if Input.is_action_pressed("ui_up"):
	velocity += -transform.basis.z * speed

I would love to learn GDScript, and I followed few tutorials, but its getting much harder when I try to do it on my own from scratch, and I couldn't find comprehensive documentation for the beginner level. Can you give me some tips how I should go about it.. Is my first time I try to learn a program language. Thx

TwistedTwigleg

My bad, I totally missed that the scene is in 3D. I should have noticed that the velocity had a Z axis. As you found, using the transform.basis.z gives you the forward direction in local space. You might want to normalize the direction though, as any change in the node's scale may effect the vector returned by transform.basis.z as the basis stores both the rotation and the scale.

I'm glad you were able to figure it out :smile:

Danilo

Much appreciated =)