How to make a node rotate around another one?

Question

I have already seen some answers about this same problem, but I need something a bit different. Let me explain.
I am making kind of a simulation of a Solar System, so I need the "planets" to rotate around a "sun", and I should be able to set the angle of these planets manually.
I would need to be able to control how fast the planet rotates around the Sun, as not all planets rotate at the same "speed".
Should I use any kind of body? Or is this possible only using a Node2D?
I have also thought about using a pre-made Animation in the Animation Player, because I think that would be better (in terms of performance, because the game would not actually rotate and execute the code in _process()) but the main problem I see is that, in that case, it would be hard to set an angle manually.
How could I make this work?
Thanks .

Answer 1

I'm doing a kind of similar thing in a little test project, where I have a reticule circling around my player based on mouse position.

In my case I have an "anchor" node, which I'd assume you'd position over your sun. I just use a plain ol' Node2D.
My reticule (in your case, a planet) is then a child of the anchor (in my case it's just a sprite). My reticule is then offset from the anchor by a certain distance in local transform - I adjust my position.x to 100, so it's always 100 units from my anchor.
Because the reticule/planet is a child, any rotation on the anchor will swing it around.

In my case I find the angle to the mouse, and set my anchor rotation to that, so that my reticule / planet is always reaching toward the mouse.
In your case you could skip the getangleto call, and just set it to the angle that you want.

In gdscript, my code is a one-liner in _process:

anchor.rotate(anchor.get_angle_to(get_global_mouse_position()))

Then, if you want the planet to move closer/further away you can just modify the local position.x to be smaller or larger.

Comments

This is working for now, but I got two questions.
Is there any way to make it rotate by itself? I mean, like rotate a degree every x time. And also, based on that, do you think it would be better to animate the rotation with a tween (related to previous question) or to execute the code in _process()?

Answer 2

You can make curves around the sun, each with a different radius

var center = Vector2(0,0)
var curve = Curve2D.new()
var circle_slice = 100
var radius
for i in range(circle_slice):
    curve.add_point((center+Vector2(radius,0).rotated(2*PI*i/circle_slice))

Then just add that curve to a path2D, and then add a PathFollow2D as a child of that.

Then in the _process() you can add just one line for a sprite to follow the PathFollow2D with different speeds. The angle is the angle of your sprite.position and Vector(1,0)

And don't worry about optimization before you even make a thing. Finish it in whatever way first, and if the end product is lagging, then optimize.