Sparrow Forum

1. 

   straydogstrut
   Administrator

   In the game i'm developing, the player controls a spider that drops down on a web when the player double taps on it. I want to have the spider return to the top of the screen after dropping down. At the moment, i'm using two tweens: SP_TRANSITION_EASE_OUT_ELASTIC to drop down, and SP_TRANSITION_LINEAR to return. I'm not sure these are the final tweens I want to use, but the bounciness of the elastic one is close to what I have in mind.

   Currently, i'm calling the returning tween once the elastic one has completed - so in its SP_EVENT_TYPE_TWEEN_COMPLETED event - but I notice there is a bit of a delay before the second tween takes over. I would rather the spider drops down and then straight back up again but with a bit of bounce. Actually, i've just tried using two Linear tweens and it does go straight back up, so I think the delay is to do with the time it takes the Elastic tween to stop bouncing? Any suggestions for getting the behaviour i'm after? (like a yo-yo I suppose)

   Also, for more complicated movement patterns, am I able to chain tweens, and if so, would this be done in the way i'm doing it with these two? ie, calling the next tween in the previous one's SP_EVENT_TYPE_TWEEN_COMPLETED event.

   Posted 1 year ago #
2. 

   Daniel
   Primary Feather

   Hi!

   The most simple way to have tweens start one after another is by using the "delay" property. Here's an example:

   SPTween *downTween = [SPTween tweenWithTarget:spider time:0.5];
   [downTween animateProperty:@"y" targetValue:300.0f];
   [myJuggler addObject:downTween];
   
   SPTween *upTween = [SPTween tweenWithTarget:spider time:0.5];
   [upTween animateProperty:@"y" targetValue:spider.y];
   upTween.delay = downTween.time; // <-- this is the important line =)
   [myJuggler addObject:upTween];

   This should be easier to do than starting it in the completed event.

   If your down- and up-movement still does not look as planned, you could create your own transition function, perhaps by creating and a copy of the bounce function and modifying it. That can be done by extending the "SPTransitions" class with the function you want. The transition type will then be simply the name of the function without the colon.

   That will require a little bit of experimentation, but in theory it should work =)

   Daniel

   Posted 1 year ago #
3. 

   straydogstrut
   Administrator

   Hi Daniel,

   Thanks, that's perfect! I still need to tweak it, and I think I may extend one of the other tweens to get the look I want, but delaying tweens like that is much better than having lots of completed events. Again, Sparrow proves a joy to work with=)

   Posted 1 year ago #
4. 

   Daniel
   Primary Feather

   Thanks, I'm happy to hear that =)

   Posted 1 year ago #

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