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Hello,
I'm trying to learn the basics of Cocos2d. I think it's best practice to use sprite sheets to create sprites, but I'm not sure where I should initialize the sprite sheets. If I do it in a particular scene (the game scene for instance) and store the sprite sheet pointer in an instance variable, but I need a sprite from that sheet in the menu scene, how would I call it?
Thank you,
Benoit
You would initiate a new sprite sheet for the menu scene.
edit: By scene, I'm assuming you are meaning a "scene" according to the cocos2d vocabulary, and not in a broader context.
Ok thanks. :) I was thinking I could use only 1 sprite sheet for my whole game, but it sounds good to have one per scene.
EDIT: What would be the "broader context"?
Broader context: It is possible that you meant "Scene" as in "A menu scene/image/tableau I put in front of my game, while the actual cocos2d 'scene' for the game is still running". In this broader meaning of the word "scene", not strictly defined to the confines of the cocos2d definition, I might add the admonition that defining two sprite sheets from the same source image would cause errors, if they are running in parallel.
If they are in completely different cocos2d 'scenes' though, you are right as rain. In your situation this is more likely an aside than a comment of any real insight or use.
Ok, I understand. Thanks for elaborating, it's really helpful. So is it normal practice to define sprite sheets from the same source image in 2 different scenes? I was thinking making a different image file for each sprite sheet/scene...
Another n00b question: I suppose cocos2d handles textures internally, but is it good practice to create many CCSprite instances from the same image file or sprite sheet instance (for the enemies in a game, for example)?
Defining sprite sheets from the same source image in 2 different scenes is not only normal, it's really just the only way that makes sense. I'd also recommend looking into Zwoptex if you haven't already. Having two identical sprite sheets for 2 different scenes would be wasting space/bandwidth.
The amount of CCSprite's you can make from a spritesheet while not unlimited, in practice is defined not by a hard limitation as much as by how many you can cram in there before the phone's processor starts to croak. You can easily have thousands if you optimize well.
I'm assuming the same holds for making CCSprites from image files, but this is from memory so perhaps someone would like to correct me.
Uhm, I'm confused.
Defining sprite sheets from the same source image in 2 different scenes is not only normal, it's really just the only way that makes sense. I'd also recommend looking into Zwoptex if you haven't already. Having two identical sprite sheets for 2 different scenes would be wasting space/bandwidth.
No, the sprite sheets would not be identical. I meant 2 different files (with different images inside), instead of one with all the images. Why is using the same source image the only way that makes sense? :S Maybe you thought I wanted to have the same sprite sheet?
The amount of CCSprite's you can make from a spritesheet while not unlimited, in practice is defined not by a hard limitation as much as by how many you can cram in there before the phone's processor starts to croak. You can easily have thousands if you optimize well.
Is the image somehow duplicated in the memory, or does it only use memory for the instance variables of the CCSprites? I'm just wondering what's the best way to have multiple objects on the screen that use the same image.
Thanks again!
One sprite sheet for one set of images, correct, it was my understanding that you wished to use images from one sprite sheet in two different scenes.
If you are using two different sets of images, then yes in most situations two different sprite sheets would be the way to go.
The image exists only once in texture memory, if you only initialize it once. OpenGL then draws that 1 single texture on the screen as many times as you'd like it to. Think of it as painting with a rubber stamp. Defining it more than once only gobbles up texture memory, it would be as useless as having several rubber stamps with the same image, you only need one, no matter how many times you are going to draw that stamp on the screen.
Spritesheets are recommend because they are a nice big fat memory palette of rubber stamps that OpenGL can use, instead of having to define each texture by itself. This speeds the process of OpenGL drawing (stamping) the textures onto the screen, as defined by you the programmer, much faster.
Great, thanks! So initializing a sprite with the method initWithSpriteSheet:(CCSpriteSheet*)spritesheet rect:(CGRect)rect doesn't gobble up texture memory at all? Only initializing the sprite sheet itself does, am I right?
Also, in most Cocos2d projects, are the objects we see on the screen instances of the CCSprite class, or do we normally write a subclass for entities or something? Very general question, and I suppose it really depends on the game, but I thought I'd ask anyway because I'm not sure where to start.
Thank you very much for your time.
I see that [CCSprite spriteWithSpriteSheet: rect:] is almost equivalent and there doesn't seem to be another way to initialize new sprite instances from an existing sprite sheet, so I suppose it doesn't increase the texture memory.
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