cocos2d for iPhone

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

1. 

   friken
   Member

   I have an issue I can't seem to sort out. What I am trying todo:

   - have a character animate (not frames, but sprite pieces) while also moving position.

   code:
   id amove = [MoveBy actionWithDuration:5 position:ccp(-5,0)];

   //HeadMovement
   id aheadmove1 = [MoveBy actionWithDuration:0.15 position:ccp(0,-3)];
   id aheadmove2 = [Sequence actions: aheadmove1, [aheadmove1 reverse], nil];
   id aheadrot1 = [RotateBy actionWithDuration:0.15 angle: -5];
   id aheadrot2 = [Sequence actions: aheadrot1, [aheadrot1 reverse], nil];
   id headspawn = [Spawn actions: aheadmove2, aheadrot2, nil];
   id shead = [RepeatForever actionWithAction:headspawn];
   [asHead runAction:shead];
   [asHead runAction:amove];

   the code is only for the head, imaging similar to the body, leftfoot, and rightfoot. I get the walking foot shuffle, headbobbing, body bobbing etc fine. The issue I have is I can't figure out how to have the walking animiation playing while also moving all objects forward to a new position. If I have two different MoveBy in the sequence it gets reset back to starting position by the repeatforever needed for the bobbing movement.

   Posted 2 years ago #
2. 

   friken
   Member

   I've spent a ton of time on this and thought I'd save a lot of memory by not animating with frames in an atlas, and instead have feet, arms, body, head etc. Seems to be something cocos2d just isn't meant todo?

   Posted 2 years ago #
3. 

   Clain
   Member

   You'd probably save memory by having separate animations for body parts instead of having much more animations for the whole character. But I think you're going to have a lot more work to do (I mean more code) to animate your character. Unless there's a significant difference in size (number of pixels) between your sprite sheet(s) for body parts and your sprite sheet(s) for the whole character, I wouldn't go your way. But that's just my opinion.

   Now, back to your problem : I think you should call the "global move" action (your id amove) on the AtlasSpriteManager which is the parent of the body parts. For example, something like this :
   

   [asHead runAction:shead];
   [asBody runAction:sbody];
   [asFeet runAction:sfeet];
   [asmgrCharacter runAction:amove];

   where asHead, asBody and asFeet are children of asmgrCharacter.

   Posted 2 years ago #
4. 

   friken
   Member

   Clain,

   Thanks! Moving the manager was the trick. I didn't think to try it. I assumed you could only move the sprites and not the manager. That does allow me to move the whole character while having the individual parts animate on a loop. I'm new to cocos2d, coming off a Unity project. So far, I'm very impressed by the cocos2d sprite library. Unity is a bit of a pita to make a 2d game with. Very doable, but there are a lot of things that get in the way... example: like lack of anchor points for rotation. You have to make oversized sprites to get your centerpoint moved.

   I've done a number of projects using sprite animation frames and wanted to try something different this time and use code to animate body parts -- a poor man's bone system of sorts. So far so good, as it doesn't take much code to made a pretty convincing walk animation using cocos2d actions. I even switched it around a bit stopped foot movement for a dance.. lol. He wiggles pretty good to some techno.

   Thanks again. problem solved :)

   Posted 2 years ago #
5. 

   PhilM
   Member

   Be interested to see how that turns out, sounds like an interesting way to construct a character!

   Posted 2 years ago #
6. 

   friken
   Member

   PhilM,

   I have an initial walking function done. I captured a quick video here:

   http://cid-91b025a901b3f5cb.skydrive.live.com/self.aspx/.Public/Klunk.mov

   overall I think it will like using this system as I can get silky smooth animation without spending a ton of time in photoshop making a zillion frames. I admit you will spend almost as much time in code tweaking the animation sequences per body part. The animation from the link is using a single sprite frame cutup with head,body,arm,frontfoot,backfoot.

   the video blurs it out a lot as it is h264 encoded. video is at 30fps where the animation is running 60fps in the simulator so it is much smoother in engine.

   Posted 2 years ago #
7. 

   Codemattic
   Moderator

   terrific, an articulated animated 2d sprite. The animation looks very smooth.

   Posted 2 years ago #
8. 

   PhilM
   Member

   Yea, runs very smooth! I like the little head bob as well, nice touch ; )

   Posted 2 years ago #
9. 

   friken
   Member

   Thanks for the feedback.

   Since this is the first time I've done this sort of animation for sprites, I'll add some things learned here for anyone else trying the same.

   - bit obvious but the more body parts you cut to be individual the better results, but more code involved.

   - when doing things like rotate 10 deg this way then reverse it, make sure all bodyparts start and return to starting position within the same amount of time. If they don't you get a bit wierd of results that look out of sync.

   - Don't use Repeatforever as it is difficult (at least I couldn't sort it out) to ensure when you stop the actions like walking to have the bodyparts return to initial position. Instead use your gameloop and check a bools like stillwalking and walkanimating. If the character hasn't reached the target position and your walkaction is completed, call it again. The only slight drawback of this is that when you reach the goal position and stop you may have a little more animation before the action completes. My walking action is 0.3seconds though so it is very minor. May be more of an issue for more complex movements.

   - Ensure your actions are reused. I put a dozen instances of the character onscreen all walking and if you recreate the actions every time they get used you create a very obvious twitch in the animation.

   - Use cool built in stuff like flipX if you have a character that walks right or left. You can use a single rendering/cutup of the character and use flipx. One note on this ensure your shading/lighting for the character is not over the top or it will look weird that your lightsource keeps shifting. This works well for a cartoon like character but would likely look too strange for a high detail/lit character.

   - When making the sprite, keep the cut parts width all the same and position them where you want them within that width. The reason for this is if you don't, you will have to have different X/Y offsets if you use flipx. If you keep everything lined up you can use flipx without any offsets or anchors.

   - Use anchors for things like arms so the arm swings from the shoulder. One thing I didn't like about anchor is that it changes the size of the sprite so you do need to also use offsets, x or y depending on which/both axes you change anchor of.

   Posted 2 years ago #
10. 

    PhilM
    Member

    Cheers for all the tips. Looks like you've been busy!

    I've thankfully got an animator that does most stuff in Flash, and I then export them as png sequences, and atlas them up.

    Although I may have a project coming up that requires fairly large characters on the screen, & the only way to keep things running smooth might be to go this way, otherwise I'd be looking at a load of large atlas sprites, which incur a performance hit.

    Thanks.

    Posted 2 years ago #

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