cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   m3th0s
   Member

   I would like to move a sprite by ccp(x,y). While the sprite is moving, I sometimes need it to move by ccp(P,Q) additionally.
   How can I achieve that?

   Things like:
   

   id action1 = [CCMoveBy actionWithDuration: 2 position: ccp(-80,0)];
   id action2  = [CCMoveBy actionWithDuration: 2 position: ccp(80,80)];
   
   [sp runAction: action1];
   [sp runAction: action2];

   do not seem to work: The first action is ignored completely.

   Grouping the actions did not work, either:
   

   id spawn = [CCSpawn actions: action1, action2, nil];
   [sprite runAction: spawn];

   Posted 1 year ago #
2. 

   randomtruth
   Member

   I am confused. Do you want to use 2 actions at the same time on one sprite?

   If so you would use CCSpawn.

   Posted 1 year ago #
3. 

   m3th0s
   Member

   I modified the first post slightly ^^
   I don't think CCSpawn is what I need, since the second action needs to be run with a delay, that is unknown at the time action1 is run.

   Posted 1 year ago #
4. 

   randomtruth
   Member

   Something like this would work.

   CCSprite *sp;
   -(void)move
   {
   id action1 = [CCMoveBy actionWithDuration: 2 position: ccp(-80,0)];
   [sp runAction:action1];
   }
   -(void)move2 //after delay
   {
   id action2  = [CCMoveBy actionWithDuration: 2 position: ccp(80,80)];
   [sp runAction:action2];
   }

   Posted 1 year ago #
5. 

   m3th0s
   Member

   I thought, that would work. But it doesn't.
   When the second action is run, the first seems to get aborted.
   I also tried this with
   

   id action1  = [CCMoveBy actionWithDuration: 2 position: ccp(-80,0)];
   id action2  = [CCMoveBy actionWithDuration: 2 position: ccp(80,0)];

   So the sprite would be at the same position, it was before both actions were run.
   But strangely thats not the case.

   It only works, if both actions are run one after another.

   Posted 1 year ago #
6. 

   protito
   Member

   I think for what you want to do actions won't help.. set the position in your step

   Posted 1 year ago #
7. 

   randomtruth
   Member

   Its a problem with the MoveBy action. The sprite keeps the original position in its array until it finishes moving. I dont think that happens with CCMoveTo though.

   Posted 1 year ago #
8. 

   bradparks
   Member

   I think you'd have the same problem with CCMoveTo as well..... i think what you can do is modify CCMoveBy to always have it's "startPosition" updated to it's current position... This would change all "CCMoveBy" actions though... Just add this code to whatever file you want to do the multiple MoveBy's at a time and you should be good..

   @implementation CCMoveBy (allowMultipleActions)
   -(void) update: (ccTime) t
   {
     startPosition = [(CCNode*)target position];
     [super update: t];
   }
   @end

   of course if you wanted to just create it as a new action (e.g. CCMoveByEx) then you could do so like:

   @interface CCMoveByEx: CCMoveBy
   @end

   @implementation CCMoveByEx
   -(void) update: (ccTime) t
   {
     startPosition = [(CCNode*)target position];
     [super update: t];
   }
   @end

   This is totally untested though ;-) Good luck!

   Posted 1 year ago #
9. 

   Karl
   Member

   Actually that won't work. You'll get exponential movement as a result since it is setting its new position based on the start position (which you change at each step to be "current" position), and adds a proportion of its delta (from 0.0 to 1.0).

   What you want to do is make an action that saves a time checkpoint. On each update, it determines how much time has passed since the last update, moves according to that time interval, then saves a new checkpoint.

   That way, it doesn't matter how many actions are acting upon the object, it will still move according to the time interval * delta for each action regardless of the position it ends up in after each tick.

   Posted 1 year ago #

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