CODEWITHSUNDEEP
animationluacoronasdk
antikewl
antikewl

Reputation: 51

Is there a better way of linking transitions in Corona Lua?

I'm currently animating a trash can when something gets dragged and dropped onto it with this code:

local trashUp
local trashDown

trashUp = function()
    transition.to(
    trash, {time=100, xScale=1.2, yScale=1.2, onComplete=trashDown })
end

trashDown = function()
    transition.to(
    trash, {time=100, xScale=1, yScale=1})
end

and then calling trashUp() when I want to start the animation.

The code works fine, but I can't help feel it could be coded better. Two functions to animate an object!

Is there any way I can do this more efficiently?

Upvotes: 3

Views: 2219

Answers (4)

johannes_lalala
johannes_lalala

Reputation: 595

transition.to( trash, {time=t, delta=true, xScale=1.5, transition=easing.continousLoop} )

Also very useful for purposes like that:

easing.sin = function( f, a )
  return function(t, tmax, start, d)
    return start + delta + a*math.sin( (t/tmax) *f * math.pi*2 )
  end
end

easing.sinDampened = function( f, a, damp )
  return function(t, tmax, start, d)
    return start + delta + a*math.sin( damp^(t/tmax) *f * math.pi*2 )
  end
end

...etc

Upvotes: 0

Vince Gatto
Vince Gatto

Reputation: 415

This question is pretty old, but since I was trying to do the same thing, I figured I should share what I came up with. This sequentially executes transitions that are passed in as variable args. If onComplete is supplied, it is called as its transition completes.

local function transitionSequence(target, step, ...)
  local remaining_steps = {...}
  if #remaining_steps > 0 then
    local originalOnComplete = step.onComplete
    step.onComplete = function(target)
      if originalOnComplete then
        originalOnComplete(target)
      end
      transitionSequence(target, unpack(remaining_steps))
    end
    transition.to(target, step)
  else
    transition.to(target, step)
  end
end

Example:

transitionSequence(myImage,
  {xScale=0.5, onComplete=function(t) print("squeeze") end},
  {xScale=1, onComplete=function(t) print("relax") end},
  {yScale=2, onComplete=function(t) print("stretch") end},
  {yScale=1, onComplete=function(t) print("relax again") end})

Upvotes: 0

JeffK
JeffK

Reputation: 3039

You can do it by coding the onComplete function inline with the first transition call:

animateTrash = function()
    transition.to(
        trash,
        { time=100, xScale=1.2, yScale=1.2, onComplete=
            function()
                transition.to(
                    trash,
                    {time=100, xScale=1, yScale=1})
            end
        })
end

This won't be any more efficient, but it does keep everything to do with animating the trashcan in one place. I think this approach could get quickly out of hand, though, especially if you were doing anything other than the transitions when animating the trashcan, e.g., updating your program's state, or creating/destroying other objects, etc.

Echoing jhocking's answer, this approach doesn't support canceling either.

Upvotes: 1

jhocking
jhocking

Reputation: 5577

Well you could do it in a single function by setting the second transition with delay; refer to this code example: http://developer.anscamobile.com/reference/index/transitionto

Depending on your situation however that's not necessarily less complicated, because now you have to keep track of two transitions simultaneously instead of just one transition at a time. In the code you posted you aren't keeping track of the transitions, but you probably should be in case you need to cancel them before the transition is complete (eg. the player switches scenes in the middle of the transition).

Upvotes: 1

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