A fast, easy to use, free, and community supported 2D game engine
conor
Member
This may be a general OpenGL question.
Does anyone have experience in creating electricity or thunder and making it look "cool"? I'm trying to create a tesla tower and would like the bolts of electricity to look/feel as visceral as possible. I thought I might try just doing it with a primitive draw routine and randomizing some jaggy lines to the target but it lacks the "cool" factor. Is there a way to use a texture to create the effect in OpenGl or something in cocos2d?
Thanks!
-conor
I made a lightning CocosNode whose draw routine is based off of the algorithm on this site and it works really well:
http://krazydad.com/bestiary/bestiary_lightning.html
I even modified it to split lightning streaks and fade out and such, if anyone is interested I'd share the src.
Ok I'm posting the links to the .h and .m files below. Just a quick usage guide:
You initialize the lightning with a strike point, it will draw lightning from its position to this strike point:
Lightning *lightning = [Lightning lightningWithStrikePoint:ccp(100,0)];
lightning.position = ccp(200,320);
[self addChild:lightning];Once you've set it up, you can have it strike by calling a few different methods:
-(void) strikeRandom; //Strike with a random seed
-(void) strikeWithSeed(unsigned long)seed; //strike with a given seed
-(void) strike; //Strike with last given seedSeed just defines the nature of the lightning, can be any number.
Also you can have the lightning split into two, but you need to define the second strikePoint. (With a little modification you could have it split multiple times).
lightning.split = YES;
lightning.strikePoint2 = ccp(300,0);Theres a few other properties such as the displacement values (they have default values), and I think I hardcoded the fadeout to .5 seconds.
Feel free to ask any questions about it.
I meant to say before that the strikepoint(s) are relative to position.... probably a useful bit of info.
Yeah, that Lightning was made with Cocos 0.8.2; since then 0.9 has changed the names of nearly everything, the correct name of that protocol is now "CCRGBAProtocol"; you've probably realized that "CocosNode" needs to be changed as well to "CCNode"...
Thanks tbone and jd, and yes it's somewhat outdated being made with 0.8.2, I'll probably update the link soon.
Afterthought: .99 also changed the GL state when getting to draw.... wonder if that messed up anything...
Wow!
I just want to say thanks by sharing this with us ! :)
It`s very useful for me, I definitely give you credit in my App ;)
Awesome code @mobilebros! One thing though, there is a memory leak with that right now.
After you call:
[lightning strikeRandom]; //or anything similarYou do need to release the memory. I would suggest just using something like this right after you call any strike method:
[self runAction:[CCSequence actions:[CCDelayTime actionWithDuration:.5],[CCCallFunc actionWithTarget:self selector:@selector(removeLightning)],nil]];And then when it's all done, make sure it's cleaned up:
- (void) removeLightning {
[self removeChild:lightning cleanup:YES];
lightning = nil;
}Of course, declare the following in your header & import the lightning header file:
Lightning *lightning;Great work! But when I ran the lightning 50x in the simulator, I noticed my FPS kept on dropping... this will prevent that. :)
Umm I might be misunderstanding what you're saying, but the lightning is just a CCNode like anything else, so if you allocate it you need to release it.... other than that there isn't anything else getting allocated.
Lightning *lightning = [Lightning lightningWithStrikePoint:ccp(0,0)];
[self addChild:lightning];
[lightning strike];
[self removeChild:lightning cleanup:YES];That's the basic use-case and it should be good to go.... unless I'm missing something.
thanks, I really liked this, but I believe I've found what mobilebros says
Afterthought: .99 also changed the GL state when getting to draw.... wonder if that messed up anything...
I'm using a CCPageTurnTransition between two CCLayer scene (i'm trying to make a book-like app), but when one of the scene is the one where I'm using you Lightning objects, the all scene is blended with the one coming next (both on backwards and forwards).
I'm getting this strange behaviour only if I add the lightning node to the scene
lightning = [Lightning lightningWithStrikePoint:ccp(180, -200)];
lightning4.position = ccp(179,300);
lightning4.split = YES;
lightning4.strikePoint2 = ccp(200,-100);
[self addChild:lightning];all of the others scene I my app are working fine.
Any clue from anybody?
many thanks
Well I haven't particularly looked at it in a little while, I think it was just some OpenGL state calls I was missing; I updated the source at this location:
http://www.mobile-bros.com/source/Lightning/
... I think I might have also inadvertently given away another class in that file called Tesla; not sure if that was in the old files.
This is fantastic. Plugged this post on Twitter. Every game needs more lightning.
Nice!
You must log in to post.
