Writing our own Tween easing (and looping?) functions

Comments

• Jmv38 Mod

  February 2015 Posts: 3,297

  i know it is not exactly what you ask for, but just in case you only need a pingpong once function, try this:

  -- pingpongOnce
  
  -- Use this function to perform your initial setup
  function setup()
      a = {x=100,y=100,w=50,h=50}
      pingpongOnce(2, a, {x=300} )
  
  end
  function pingpongOnce(time, subject, target,...)
      local back = {}
      for k,v in pairs(target) do back[k] = subject[k] end
      tween(time, subject, target,...)
      local arg = arg or {}
      tween.delay(time,function() tween(time, subject, back,unpack(arg)) end)
  end
  
  -- This function gets called once every frame
  function draw()
      -- This sets a dark background color 
      background(40, 40, 50)
  
      -- This sets the line thickness
      strokeWidth(5)
  
      -- Do your drawing here
      rect(a.x, a.y, a.w, a.h)
  end
  
  
  
• yojimbo2000 Mod

  February 2015 edited February 2015 Posts: 2,020

  @Jmv38 Wow, that is very clever.

  ^:)^

  Thank you!
• dave1707 Mod

  February 2015 Posts: 9,977

  This is easier for me to understand and does the same thing.

  
  function setup()
      p1={x=50,y=50}
      p2={x=400,y=600}
      p3={x=50,y=50}
      rec={x=50,y=50,w=50,h=50}
      tween1()
  end
  
  function tween1()
      tween.path(5,rec,{p1,p2,p3})
  end
  
  function draw()
      background(40, 40, 50)
      fill(255)
      rect(rec.x,rec.y,rec.w,rec.h)
  end
  
  
• Jmv38 Mod

  February 2015 Posts: 3,297

  i agree
• dave1707 Mod

  February 2015 Posts: 9,977

  @Jmv38 Actually, it can be shortened by eliminating p3 and just reusing p1 in the tween.path since we're going back to the starting point.

  
  function setup()
      p1={x=50,y=50}
      p2={x=400,y=600}
      rec={x=50,y=50,w=50,h=50}
      tween1()
  end
  
  function tween1()
      tween.path(5,rec,{p1,p2,p1})
  end
  
  function draw()
      background(40, 40, 50)
      fill(255)
      rect(rec.x,rec.y,rec.w,rec.h)
  end
  
  
• yojimbo2000 Mod

  February 2015 Posts: 2,020

  @dave1707 I keep forgetting about tween.path... I'm experimenting with it now. Although maybe a tween.sequence might be closer to a pingpong.once as path adds a spline
• yojimbo2000 Mod

  February 2015 Posts: 2,020

  This is slightly off-topic, but one thing that I think is odd about tweens is that when they're called as part of a class, and you want the callback to be a function of that class, you have to wrap it in an anonymous function. ie:

  tween(1, self, {pos=newpos}, tween.easing.SineInOut, self:myFunction()) --the function is called immediately, rather than after the tween
  tween(1, self, {pos=newpos}, tween.easing.SineInOut, self.myFunction(self)) --ditto
  tween(1, self, {pos=newpos}, tween.easing.SineInOut, self.myFunction) --function is called at the right time, but doesn't have access to self, returns an error if self is called
  tween(1, self, {pos=newpos}, tween.easing.SineInOut, function() self:myFunction() end) --success! function must be wrapped in an anonymous function to execute properly
  

  It just seems slightly wasteful, given that advice on optimising Lua recommends not repeatedly creating closures:

  http://lua-users.org/wiki/OptimisationCodingTips

  Or are repeated anonymous functions (ie you have lots of tweens firing at once) not such an issue performance wise? Am I worrying unnecessarily here?
• Simeon Admin Mod

  February 2015 Posts: 5,778

  @yojimbo2000 it's necessary in order to bind self to the function. If you wrote your function as a static method (i.e., no access to self) then you could just pass the function name.
• yojimbo2000 Mod

  February 2015 Posts: 2,020

  @Simeon and is it possible to add our own looping functions, like we can with easing?