How to reorient global velocity in a particular direction

duendecat

Hi everyone. There's a problem that I just can't get my head around, and having forgotten most of what I know about math (and an afternoon's worth of unsuccessful googling) I thought I'd ask around for an answer.

I have a global direction vector (let's call it VecA) that I would like my parent object to travel in, obtained from the global basis (y) of a child 'direction' node.

I also have an unrelated Vector3 (VecB) that contains the direction I would like the parent object to travel in the next frame. However this in global space (with global y being the forward direction).

Essentially I'd like to 'point' VecB in the direction of VecA, so that the velocity has been recalculated (reoriented?) for that particular direction. Can anyone please give me some tips / advice?

Sparrow

How about VecB.look_at(VecA)

Var lookvec = (vecb.position - veca.position).angle()
Vect.rotation = lookvec

Sparrow

Also if it's global then you may want to do global_position

There's a great doc on vectors and other subjects

https://docs.godotengine.org/en/3.2/tutorials/math/vector_math.html

duendecat

Thanks a lot for your help. Having read through my original post, I've just realised that I did an incredibly bad job of explaining the problem, so I've included some diagrams in order to explain.

I'm essentially trying to create a circle of objects in front of the player, in a 3D isometric game using C sharp.

A list representing each of the objects in the circle is looped over, and in each iteration the following code calculates the position that the new object will be inserted:

Vector3 rotated = (DirectionNode.Transform.basis.z.Rotated(new Vector3(1, 0, 0), angle));

spawnLocation = (parentEntity.Size * DirectionNode.Transform.basis.y) + (3f*rotated) + DirectionNode.GlobalTransform.origin;

This generates something like the following, when the player is facing the camera:

However (and this is the problem) when the player faces left or right the circle is still generated in exactly the same way as before (only in a different location), almost as if it is using global space for the rotations:

Whereas the desired effect would be for each of the objects to position itself relative to the direction the player is facing, like so:

I've tried everything I can think of and have been up all night trying to solve this so hopefully I'm not sounding too insane. But as you can tell, I've come to the limits of my available experience and am really not sure what's causing this, since I'm using the player's (relative) basis to rotate each object.

Some other things that might need mentioning:

The variable 'angle' above represents an angle (in radians) that is used to equally space each object within the full range of values (360 deg divided equally then converted to rad). This appears to be successfully creating a circle. The 'parentEntity.Size' is used to position the circle a certain distance away from the player. The 3 in '3f*rotated' is used to (in effect) increase the size of the circle's circumference.

So in a nutshell, what I'm trying to do is to rotate the whole circle (re-position each object) so that it faces in the direction that the player is facing. Can anyone please give any advice / solutions?

Megalomaniak

So the circle would always be right in front of the player? And always oriented, relative to the player, the same way?

duendecat

Yep, that's the idea.

Megalomaniak

So why not just parent it to the player and give it a translation offset?

Sparrow

here you go bud, the above from Megalo is the easiest solution, my solution below gives you 8 direction aiming $Sprite2 is the aiming part, changing the 3 to other values gives you distance

extends KinematicBody2D

var speed = 250
var velocity = Vector2()

func get_input():
    # Detect up/down/left/right keystate and only move when pressed.
    velocity = Vector2()
    if Input.is_action_pressed('ui_right'):
        velocity.x += 1
    if Input.is_action_pressed('ui_left'):
        velocity.x -= 1
    if Input.is_action_pressed('ui_down'):
        velocity.y += 1
    if Input.is_action_pressed('ui_up'):
        velocity.y -= 1
   ** $Sprite2.position = ((velocity).normalized() * 100) * 3**
    velocity = velocity.normalized() * speed

func _physics_process(delta):
    get_input()
    move_and_collide(velocity * delta)

Sparrow

if you need one

aimangle = ($Sprite2.global_position - self.global_position).angle()

change global_position to position depending on your usage