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How to retrieve the seperate rotation values from the gyroscope? — Gideros Forum
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    How to retrieve the seperate rotation values from the gyroscope?

    MikeHartMikeHart Guru
    edited December 2011 in General questions
    When I read up the documentation of using the gyroscope, i think that there is only one value returned from Gyroscope:getRotationRate().

    But there should be seperate values for each axxis, right?

    http://developer.apple.com/library/ios/#documentation/CoreMotion/Reference/CMGyroData_Class/Reference/Reference.html#//apple_ref/occ/cl/CMGyroData

    Or do I miss something here?
    http://michaelhartlef.carbonmade.com
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    Comments

    • atilimatilim Maintainer
      edited January 2012
      It's not described in documentation but it returns three values (x, y and z).
      require "gyroscope"
 
gyroscope:start()
local x, y, z = gyroscope:getRotationRate()
      http://en.wikipedia.org/wiki/Cytorus
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    • MikeHartMikeHart Guru
      Thank you for the quick explanation.

      Maybe this could be added to the docs.
      http://michaelhartlef.carbonmade.com
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    • atilimatilim Maintainer
      exactly
      http://en.wikipedia.org/wiki/Cytorus
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    • pmannapmanna Member
      Speaking of gyro, I was doing some tests, and data seems to be coming in at a rate (on iOS device) that is not constant. This, by itself, could not be a problem, as long as the frequency is high enough for the purpose (in my case, movement is slow, and even 5 events/sec would be enough), but, being the unit "rad/sec", the returned data should report the timestamp (and it does, on the original doc Mike reported) to allow proper calculation of the rotation. I'm not sure just using os.timer() could help, because data seemed to come in in waves, and I don't know where the bottleneck is...
      Thoughts?
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    • atilimatilim Maintainer
      edited January 2012
      I see.

      After your post, I've done some tests and here is the code that gives the most accurate results:
      require "gyroscope"
 
gyroscope:start()
 
local angx = 0
local angy = 0
local angz = 0
local function onEnterFrame(event)
    local x, y, z = gyroscope:getRotationRate()
 
    angx = angx + x * event.deltaTime
    angy = angy + y * event.deltaTime
    angz = angz + z * event.deltaTime
 
    print(angz * 180 / math.pi)
end
 
stage:addEventListener(Event.ENTER_FRAME, onEnterFrame)
      But I'm still thinking if a functionality like
      x, y, z, deltaTime = gyroscope:getRotationRate()
      can improve the accuracy.

      Maybe the best way is to internally calculate the exact rotation also and relieve the developers from doing such calculations.

      http://en.wikipedia.org/wiki/Cytorus
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