How to create Jetpack Joyride jackpot lever animation

Question

Just wondering if anybody knows how to recreate the touch lever action ?

http://www.wired.com/geekdad/wp-content/uploads/2011/08/JJ-jackpot.jpg

There's a [video of the animation in this video](http://www.youtube.com/watch?v=4vK7jebOe_4#t=132s) — dbr, Oct 22 '12 at 05:08

score 2 · Accepted Answer · answered Oct 22 '12 at 05:01

Don't know what the exact animation is but if you have to pull the lever down to activate and not just click on the lever, then you need to get the initial touch position and compare it to the final touch position. The percentage of where the current touch is between the 2 start and end positions dictates what frame of the animation is being used.

So, say you have 10 frames in your lever animation:

function lengthOf(a, b)
    local width, height = b.x-a.x, b.y-a.y
    return (width*width + height*height)^0.5
end

local startBox, endBox
local beingPulled = false
if isOver(touchPos, startBox) and touch.phase == "began" then
   beingPulled = true
end
if touch.phase == "moved" then
   if beingPulled then
      local lengthA = lengthOf(touch, startBox)
      local lengthB = lengthOf(touch, endBox)
      local totalLength = lengthA+lengthB
      local percentage = totalLength/lengthA

      lever:setFrame( math.ceil(percentage*10) )
   end
end
if touch.phase == "ended" then
   lever:resetPosition()
   beingPulled = false
end

Hi David, Thanks for the reply. yes just a pull down animation — Desmond, Oct 22 '12 at 05:12
thanks for sharing the animation video. @david that lever animation is what i need. — Desmond, Oct 22 '12 at 07:19

score 1 · Answer 2 · answered Oct 31 '12 at 09:19

You will either need 3d Object, which can be rotated a bit - to make that animation, or You could already pre-render all animation frames on animating an object (for example - You have a "lever" object).

I've done something similar - I had pre-rendered images of a rotating cube. I set all these images as animation frames like in this example: http://appsamuck.com/day2.html

And I placed invisible scrollView above this UIImageView. Then , when scrollViewDidScroll was called - I simply changed current UIImageView animation frame.

So in this case - it could be a UIScrollView, which on - for example:

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate

would setContentOffset to CGPoint(0,0) point. (with animation).

Thats my proposal. Good luck!

How to create Jetpack Joyride jackpot lever animation

2 Answers2