Rotate an object like a wheel using touch

Getting Started Newbie Questions
#1

I want to touch an object and rotate it clockwise or anticlockwise based on the touch’s x&y:

  function rotatePlayer(event)    local obj = event.target     if (event.phase == "began") then     display.getCurrentStage():setFocus( obj )         obj.startX = (event.x - obj.x)     obj.startY = (event.y - obj.y)      obj.startAngle = math.atan2( obj.startY, obj.startX ) \* (180 / math.pi)     elseif (event.phase == "moved") then     local dX = (event.x - obj.x)     local dY = (event.y - obj.y)  local angle = math.atan2( dY, dX ) \* (180 / math.pi)     local dAngle = (angle - obj.startAngle)     obj.rotation = dAngle         elseif (event.phase == "ended") then     end   end

The result is not as expected, some jerky movement and not consistent with the touch’s gesture.  Any help would be appreciated.

#2

https://forums.coronalabs.com/topic/65202-rotating-issue/Like this?

#3

** UPDATE - I won’t be following up any further on this answer, everything you need is in the answer pack **

I definitely answered this in one of my answer packs:

http://github.com/roaminggamer/RG_FreeStuff/tree/master/AskEd/2015%20Answer%20Packs

However, scott’s answer may be more accesible to you as mine uses math2d (plugin/lib)

http://www.youtube.com/watch?v=18TxGiun8Jc&t=1m29s

#4

It’s not different than my code other than subtracting the angle:

adjustment = math.atan2(dy,dx) \* 180 / PI - ball.rotation \<\<- here ball.rotation = (math.atan2(dy,dx) \* 180 / PI) - adjustment \<\<- and here

But the result is still the same, it’s not working as intended for me. 

#5

Any help would be appreciated here guys, I’m not sure if the problem is with my calculation ( most likely not because I have the same calculation working in SpriteKit) or with the way Corona handles the touch events. 

#6

The demo works fine on my computer, what is your fps set on?

#7

https://www.dropbox.com/sh/oh3wzps9datd5a3/AAAxPsP4T7PENFB3Px362D0Ra?dl=0

#8

First of all, let me thank you for your effort.

Second, your FPS question  ( which I set to 60 btw) inspired me to test the game on my device, the games (both yours and mine)  work perfectly on the device but not in the Corona simulator.  I don’t know why despite having both Xcode and Unity run perfectly fine on my machine, granted that it’s not new or powerful ( 2013 MacBook Air) but heavier simulators work fine on it. 

In the simulator, there is a lot of stuttering and jerky movement, and it’s like the object is not following the touch 1:1 

#9

i am on a macbook pro 2012 and it works fine in simulator. Macbook airs are usually not a powerful pros. But you still should not being that much stuttering on a 2013 air. What version of corona are you running? What are your specs on your computer (can be found by clicking apple icon in top left and about this mac)?

#10

It may be a ram problem, but i am not sure. Try turning you computer on and off. Fun fact apple recommends doing this once a week to clear out memory leaks.

#11

Yes, restarting definitely helped. I was worried for a while there because both Lua & Corona are supposed to be very lightweight. 

#12

https://forums.coronalabs.com/topic/65202-rotating-issue/Like this?

#13

** UPDATE - I won’t be following up any further on this answer, everything you need is in the answer pack **

I definitely answered this in one of my answer packs:

http://github.com/roaminggamer/RG_FreeStuff/tree/master/AskEd/2015%20Answer%20Packs

However, scott’s answer may be more accesible to you as mine uses math2d (plugin/lib)

http://www.youtube.com/watch?v=18TxGiun8Jc&t=1m29s

#14

It’s not different than my code other than subtracting the angle:

adjustment = math.atan2(dy,dx) \* 180 / PI - ball.rotation \<\<- here ball.rotation = (math.atan2(dy,dx) \* 180 / PI) - adjustment \<\<- and here

But the result is still the same, it’s not working as intended for me. 

#15

Any help would be appreciated here guys, I’m not sure if the problem is with my calculation ( most likely not because I have the same calculation working in SpriteKit) or with the way Corona handles the touch events. 

#16

The demo works fine on my computer, what is your fps set on?

#17

https://www.dropbox.com/sh/oh3wzps9datd5a3/AAAxPsP4T7PENFB3Px362D0Ra?dl=0

#18

First of all, let me thank you for your effort.

Second, your FPS question  ( which I set to 60 btw) inspired me to test the game on my device, the games (both yours and mine)  work perfectly on the device but not in the Corona simulator.  I don’t know why despite having both Xcode and Unity run perfectly fine on my machine, granted that it’s not new or powerful ( 2013 MacBook Air) but heavier simulators work fine on it. 

In the simulator, there is a lot of stuttering and jerky movement, and it’s like the object is not following the touch 1:1 

#19

i am on a macbook pro 2012 and it works fine in simulator. Macbook airs are usually not a powerful pros. But you still should not being that much stuttering on a 2013 air. What version of corona are you running? What are your specs on your computer (can be found by clicking apple icon in top left and about this mac)?

#20

It may be a ram problem, but i am not sure. Try turning you computer on and off. Fun fact apple recommends doing this once a week to clear out memory leaks.