How do I count rotations

Game Engine Game Engine Support and Discussion
1

Hello,

I got two question:

First, I want to count the rotation of an object in degrees. Not only from 0 to 360 but also keep counting after a full rotation was done, so add up the rotation (540, 720, 900, 1080 etc. with every step inbetween)

How can I do this?
To get the z-rotation I have the follwing script:

		angleXYZ = self.object.worldOrientation.to_euler()
		angleZ = math.degrees(angleXYZ[2])+180

With this conversion the angle goes from -180 to 180. So I add 180 to have it range from 0-360.
Another problem I got with this is that the player is always starting at angle 180 instead of 0/360.
Any idea how to fix this?

Thanks for any help in advance!!

2

What is driving the rotation?

If it’s a script, then you can just store the amount you’re rotating the object by in a property.

Or, maybe use a animation instead which extrudes to infinity. Simply keep moving it along the frames and keep track of what frame you’re on.

3

Unfortunately, the rotation is impulsed by torque force

4

If it never rotated more than 180 degrees in one frame, then you could keep track of the change in rotation every frame. If it goes from +180 to -180 then add (or remove, depending on direction) 360 to your count.

5

Thanks for the ideas…
I had this approach before. The problem is that the object is a dynamic object which has some slight variations in its rotation due to its physics.
So it will rotate slightly a bit forwards and backwards naturally resulting in this adding up to the “rotation counter” and giving unprecise results.

I was thinking about adding 4 objects around the main object and everytime one of them is detected via a ray or something, it would add up 90° to the rotation counter.
But this would limit it to 90° steps

6

Presumably you’d only need to know how many full rotations it’s done. That would make your calculation something like: (num_full_rotations * 360) + current_rotation

That way, it doesn’t matter if your object rocks back and forward, as long as you’re accurately tracking when it goes under -180 or over 180.

E.g.
If last frame it was on 160, and now it’s on -155, then the closest path to that assumes it went over 180 and rolled over to -180, thus we’d add 1 to the num_full_rotations.

1 Like
7

That makes sense! Thanks a lot :slight_smile: