Plane round like a circle

TwistedMind

Hello everyone,

I make a code which command to a plane to fly in circle, this circle is cyclic. But actually, he moves square by square and i'd like to improve that to make it more swiftly. So whithout square by square, just the start location must be unchanged.

Here actually i have done: the green circle is what i'm looking for.

I know is it possible to make coordinates to obtain the green circle, but not how to code that;
This theoric code probably start to 0 degrees/radian, my plane can come from anywhere (Red square is the target location before to start the round "state"), so the circle must be adapted in consequence, i mean the target location must be the "0 degree/radian".

But is it possible to make a complicated thing ?

Zini

I am not entirely sure if I understand the question. But the math is easy enough.

Assuming you have the angle (α) and the radius of the circle (r) then you can obtain the matching coordinates by:

x = cos(α) * r
y = sin(a) * r

kkkkkkabc

And then the velocity direction is the normal of the radius, look at forward

TwistedMind

If you need more informations, please ask what you need to understand.
The angle is an unknown, the radius can be determinated manually.

So, if i understand, in practice:

var radius = 100
var pointNbr = 12 # the number of points of the "circle"
var list = []

for i in range(pointNbr):
     var angle = ? # i should be here probably and must add Pi * 2, correct ?
     var pointPosition = Vector2(cos(angle) * radius, sin(angle) * radius)
     list.append(redTarget + pointPosition)

unitPath.append_array(list)

I don't need to use world to map to have a square by square position, just the start and end position (this is redTarget).

But it miss two things:

The direction to follow the circle, if the plane goes from the left, it must make the round from the right to left (anti-clockwise) and the inverse if the plane goes from the right (clockwise);
redTarget will be the "center", it's not i want, it should be in the top of the circle to make that logic (in my draw, the red arrow is the plane coming from).

xyz

TwistedMind One point is not enough to define a circle. You need to have at least two points; the center plus one point on the perimeter. You have the perimeter point but you don't have the center.

xyz

TwistedMind There is a cheap trick you could try that may do what you want without ever calculating the exact circle.

Once the plane reaches the red point, continue moving at the same velocity but each frame rotate the velocity vector by a small amount. The plane will continue to move on a circular path whose radius will depend on the velocity angle increment (aka angular velocity)

TwistedMind

One point is not enough to define a circle. You need to have at least two points; the center plus one point on the perimeter. You have the perimeter point but you don't have the center.

Got it, it's redTarget. When redTarget is reached, the plane must choice to:

Waiting stance and round over in circle;
If fighter class, looking for enemy target and go to it.

Once the plane reaches the red point, continue moving at the same velocity but each frame rotate the velocity vector by a small amount. The plane will continue to move on a circular path whose radius will depend on the velocity angle increment (aka angular velocity).

And so the value will progresssively switch to make the round ? Like this draw in green (left) ? Initialy, i was looking for the 2nd option (the right one).

xyz

TwistedMind Do you know the center of the circle or not?

You haven't defined the problem precisely enough. Do we know the circle center or the red point? Or both? Is plane allowed to move on a curved path prior to reaching the red point or it must go in a straight line? How the plane is supposed to behave if it's already inside the circle prior to getting the command to go circling?

TwistedMind

No. the "center" i draw is the last point where the plane must go in. After that, nothing.

That's why i considered this last point is my start point to move somewhere.

xyz

TwistedMind So the red point is the plane's actual target? Circle center has no any significance? If that's the case then you can do exactly what I've said before. When the red point is reached continue moving but rotate the velocity vector and you'll get exactly what your right diagram is showing.

xyz

TwistedMind Then you've got the solution. Just rotate the velocity vector and you're done.

TwistedMind

I can't rotate the node, because the sprite will be rotated too, i can't do that.

Actually, i have this:

var round = [Vector2(-1, 0), Vector2(-2, 1), Vector2(-3, 2), Vector2(-3, 3), Vector2(-2, 4),
		Vector2(-1, 5), Vector2(0, 5), Vector2(1, 4), Vector2(2, 3), Vector2(2, 2), Vector2(1, 1)]
var path = [ ]
var firstRound = true
var velocityFactor = 50

if firstRound:
	for point in round:
		path.append(flyTarget + Map.map_to_world(point))

	unitPath.append_array(path)
	unitPath.append(flyTarget)
	firstRound = false
	velocity = position.direction_to(unitPath[step]) * velocityFactor
	moveScript.configFrame()
else:
	step = step - path.size() - 1
	velocity = position.direction_to(unitPath[step]) * velocityFactor
	moveScript.configFrame()

In practice, i have this below (yellow arrow show the direction i want the plane must take):

I need something more smoothly. This is too "raw", "square".

xyz

TwistedMind You don't rotate the node, you rotate the velocity vector.

TwistedMind

Uh ? Vector2.rotated(x) ?

trying in a fresh project...

Ahh !!!... Yes, that's perfect !

I was thought this litterally rotate the node. Now i understand why it can be useful. I must link that with the correct sprite animation, correct speed and it will be done.

Stop the rotated function at the correct time shouldn't be complicated... i have to see.

Thank you @xyz, @kkkkkkabc and @Zini.