Sparrow Forum

1. 

   marwic
   Member

   Hi guys!

   I struggle with how to handle transitions between scenes in my Sparrow projects.

   I usually end up just adding all scenes (SPSprite subclasses really) to the stage at once, but outside the viewable area. I then create hide: and show: methods in each "scene" class. These methods animates objects into (or out of) the viewable area. For instance, a show: might look like this:

   - (void) show
   {
   	self.touchable = NO;
   	float time = 1.0f;
   	[self updateButtons:-1];
   	SPTween *tween = [SPTween tweenWithTarget:self time:time transition:SP_TRANSITION_EASE_OUT_BACK];
   	self.rotation = -PI;
   	[tween animateProperty:@"rotation" targetValue:0];
   	[self.stage.juggler addObject:tween];
   	[[self.stage.juggler delayInvocationAtTarget:self byTime:time] setTouchable:YES];
   }

   This code simply rotates the scene into the viewable area. To hide it, just do the opposite. Other variations animates all the different objects into the screen individually from different corners of the viewport. It works but is a bit messy and (probably) odd to have all objects rendered outside the viewport.

   As an example, consider writing something like a slideshow (powerpoint) viewer in Sparrow where each page would be a Scene and there would be different transitions for each slide. Like fade in/crossover, flip, rotate, 3d flip etc...

   How would you do this? How do you do it today? Looking forward to your ideas!

   Thanks!

   Posted 1 year ago #
2. 

   Daniel
   Primary Feather

   I once created a menu system in which the different screens had to be shown or hidden, just as what you are proposing. (Unfortunately, that was not on the iPhone, though).

   In principle, it worked just like you describe it; the only difference is that the menu screens were created only when they were required. So, I would create a menu screen, add it to the stage outside the visible area, and then move it in. The movement would not be done by the screen itself, but by the menu class that would handle all the screens. While the new screen would move in, the old screen would move out -- and at the end of that animation, the old screen would be released.

   In UIKit, Apple's UINavigationController works similarly, with "push" and "pop" methods to move to the next screen / return to the last screen.

   Posted 1 year ago #

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