cocos2d for iPhone

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

1. 

   finder39
   Member

   So i have a big thing that i want to implement and I need to do it soon. I would really appreciate some help from the community as i cannot get it play back fluidly.

   basically i am trying to record a particle as it moves (as it is user controlled) and "record" the movement to play back. Would you be willing to give me a hand with this? I have some basic code down but it doesn't work fluidly. I would like to get this done this weekend if I can and would be willing to give you $50 (not a lot i know, can give you more once it goes on sale as i have no $$ right now) to help me in such short notice. I want to be able to record up to 5 or 10 different particles.

   for informational purposes of the variables
   theParticles is a NSMutableArray
   particle1X and particle1Y are arrays of int

   i call it like this when i want to start recording
   

   [self schedule:@selector(createParticlePositionArrays:) interval:1/20.0];

   which calls this function
   

   - (void)createParticlePositionArrays:(ccTime) dt {
   	for (CCParticleSystemQuad *particleZ in theParticles) {
   		particle1X[currentArrayIndex] = particleZ.position.x;
   		particle1Y[currentArrayIndex] = particleZ.position.y;
   		currentArrayIndex++;
   		if (currentArrayIndex == 100) {
   			[self unschedule:@selector(createParticlePositionArrays:)];
   			ParticleActions = 0;
   			doingParticleAction = 0;
   			currentArrayIndex = 0;
   			CCParticleSystemQuad *particle1;
   			particle1 = [CCParticleSystemQuad particleWithFile:@"fire.plist"];
   			particle1.position = ccp(particle1X[0], particle1Y[0]);
   			particle1.tag = 101;
   			[self addChild:particle1];
   			[self schedule:@selector(MoveSavedParticles:) interval:1/20.0];
   		}
   		return;
   	}
   }

   and i play it back with this
   

   - (void)MoveSavedParticles:(ccTime) dt {
   	CCArray *theChildren = self.children;
   	CCParticleSystemQuad* node;
   	CCARRAY_FOREACH(theChildren, node)
   	{
   		if (node.tag == 101) {
   			[node runAction:[CCMoveTo actionWithDuration:1/20.0 position:ccp(particle1X[particle1ArraySavedIndex], particle1Y[particle1ArraySavedIndex])]];
   			particle1ArraySavedIndex++;
   			if (particle1X[particle1ArraySavedIndex] == 0) {
   				particle1ArraySavedIndex = 0;
   				[node runAction:[CCMoveTo actionWithDuration:0 position:ccp(particle1X[particle1ArraySavedIndex], particle1Y[particle1ArraySavedIndex])]];
   			}
   			return;
   		}
   	}
   }

   if possible i would also like to make it where it records multiple particles at once. but the main part is getting the recording and playback to be fluid, then i can deal with the rest probably :)

   Posted 1 year ago #
2. 

   Birkemose
   Moderator

   I worked with this, and actually you can even get a particlesystem to run backwards if you feed it a negative time. Very cool actually.

   But that is besides the point, just to prove that I am well worth the 50 bucks ;)

   My own approach to this, was to record the particles as they were created, because when the initial data is set, there is no need to record the life of them. It is predetermined ... if you believe in that kinda stuff.
   In playback, you just override the emitter with your saved particles.
   That was easy.

   Now where is my money?

   Posted 1 year ago #
3. 

   finder39
   Member

   what do you mean by as they were created.

   it is user controlled so its movement changes over time by setting its position. is there a way to replicate that exactly?

   Posted 1 year ago #
4. 

   Birkemose
   Moderator

   If the particle system moves around, you ofcause have to save its position also, but the idea was that you dont need to save position for every particle. You can play back large complex particle systems this way.

   Posted 1 year ago #
5. 

   finder39
   Member

   with a change of position how often did you grab the new position? 20 times a second or was it more?

   also, how did you store the data? in arrays like im doing or in a different manner?

   check your private messages. I am willing to pay for help with this. It is a HUGE thing that i need and it needs to be done right :)

   Posted 1 year ago #
6. 

   Birkemose
   Moderator

   I wouldnt take your money, and it was something I toyed with a while back, because I wanted to implement playback that included both forward and reverse. I basicly got it to work, but decided to save it for another day.

   How often you save the basic position, would have to depend on what kind of movement. A user input would have to be quite often, where as a missile trail could be less frequent. Write your code so you easily can change samplerate, and experiment.

   I am old school, so I dont dynamicly allocate and deallocate unless I am forced to it. It has been a while, but I think I added a record-buffer allocating the same amount of particles as you do when you create your system. You could argue that this is brute force, but unless you have a gazillion particle systems, it will probably eat up less memory than your splash screen.
   When the particle system was fired, I saved a copy of each new generated particle, and then used these for playback. I think I had to fix emitter timing, but I am not sure.

   I ended up with being able to recreate explosions, and being able to wind forwards and backwards. It looked cool, and is something I certainly will use some day.

   Posted 1 year ago #

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