Problem preloading images « cocos2d for iPhone

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Problem preloading images

(16 posts) (4 voices)

Started 1 year ago by Webtopia
Latest reply from Webtopia

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Webtopia
Member
Hi,

I'm having no end of trouble trying to preload my images that I want to use as CCSprites. They are really large since I need to zoom into one part of them. I've searched all through the forums over the last few days and looked at Textures and so on and just managed to confuse myself.

I have a number of Scenes which I use so I don't have to worry too much about memory. Each Scene had basically one line of code that adds the layer to it.

For Example
```
#import "HomeScene.h"
#import "HomeLayer.h"

@implementation HomeScene

- (id) init {

	self = [super init];
	if (self != nil) {
		[self addChild:[HomeLayer node]];
	}

	return self;
}

- (void) dealloc {

	[super dealloc];
}

@end
```
The basic structure of my app is

App Delegate
LoadingScene -> LoadingLayer
HomeScene -> HomeLayer
GameScene1 -> GameLayer1

etc.

To move between scenes I simply use this code

[[CCDirector sharedDirector] pushScene:[GameScene1 node]]

My problem is that I want to load a sprite ie.

theSprite = [CCSprite spriteWithFile:@"bigImage.jpg"];

in the LoadingScene but then use it in the the Game1Scene.

I may be being totally stupid. Is it possible to do this or does it gets cleared from memory when I push the scene?

Can I load it to a texture and then access it later? How would I do that?

At the moment when I begin my game from the HomeLayer there's an unacceptably long delay which may cause users to think the game has frozen.

Any help on this would be greatly appreciated.

Sorry if it's a stupid question.

Thanks,
Travis
Posted 1 year ago #
Webtopia
Member
Hi again,

OK I've looked at the sample code. I think I need to do something like this in the LoadingLayer.
```
UIImage *image = [[UIImage alloc] initWithContentsOfFile:[CCFileUtils fullPathFromRelativePath: @"test_image.png" ]];
	CGImageRef imageref = [image CGImage];
	CCTexture2D *tex = [[CCTextureCache sharedTextureCache] addCGImage:imageref forKey:@"test_image.png"];
```
Then I should access the image by using

CCSprite *img = [CCSprite spriteWithTexture:tex];

In the GameLayer1.

But with some reference to the other LoadingLayer instead of just tex. Still working out how to do that.

Is this right?

Any ideas?

Thanks
Posted 1 year ago #
Steve Oldmeadow
Administrator
If you code:
```
theSprite = [CCSprite spriteWithFile:@"bigImage.jpg"];
```
in any scene then the TextureCache first checks to see if a texture had been loaded for "bigImage.jpg", if it has it returns that texture otherwise it loads "bigImage.jpg" into a texture. "bigImage.jpg" will stay in the TextureCache forever unless you explicitly unload it.
Posted 1 year ago #
Webtopia
Member

OK Cool so the TextureCache works it's magic behind the scenes.

I can simply load the images into a dummy sprite that I don't use just to get the images loaded.

I also assume that there's some time saved in using png files. But I'm trying to keep my overall app size down by using .jpg. Any thoughts on that?

Posted 1 year ago #
Steve Oldmeadow
Administrator

I've never used jpegs so can't offer any advice there.

Posted 1 year ago #
Webtopia
Member

No worries, thanks very much for your help

Posted 1 year ago #
Webtopia
Member

Hmmm Now I'm having memory issues.

When I run instruments it shows I'm using over 38meg of real memory then it crashes.

I guess I need to just accept the delay when I load them and remove the images from the CCTextureCache as I use them.

Does anyone know if there is a post or some documentation I can check out to see the best way to handle this. With 8 images all around 800 x 1024 in size it's going to clog up the memory if they are all loaded.

Thanks again

Posted 1 year ago #
Webtopia
Member

** bump **
Sorry still having memory issues.

Any ideas?

Posted 1 year ago #
Steve Oldmeadow
Administrator

800 x 1024 needs 1024 x 1024. If you are using RGBA8 textures then 8 such images need 32Mb - this is way too much. Beyond 24Mb of textures causes major performance degradation on older devices. Either use a different texture format or release some of those textures.

Posted 1 year ago #
Webtopia
Member

I realise now that I need to just load them individually and cope with the time delay.

I read in best practises that I need to add this line of code to save some space.

[CCTexture2D setDefaultAlphaPixelFormat:kCCTexture2DPixelFormat_RGBA4444];

I thought I needed to add it to the app delegate but it doesn't recognise this constant kCCTexture2DPixelFormat_RGBA4444 so I'm not sure where it's supposed to go.

Thanks again for your help

Posted 1 year ago #
Steve Oldmeadow
Administrator

Those constants are defined in CCTexture2D so if that class is visible then the constants should be too. Using a 16 bit format will halve your memory usage to 16Mb so you could have them all loaded. If your images are background images and have no transparency then try kCCTexture2DPixelFormat_RGB565 as it will look slightly better than 4444. There is a tool called Damage Control that can optimise images for those low bit formats. You could also try PVRTC compressed textures, especially if your images are more photographic than pixel art.

Posted 1 year ago #
abitofcode
Moderator

This post may be helpful http://www.cocos2d-iphone.org/forum/topic/4245#post-25819

Posted 1 year ago #
Lam
Member

Yeah follow abitofcode's advice and asynchronously pre-load your textures.

I pretty much do that for all images, sounds, game data right now.

Posted 1 year ago #
Webtopia
Member

Hi thanks guys for the tips.

I'll have a go with the asynchronously pre-load.

I have some images that need to be full quality kTexture2DPixelFormat_RGB8888. But others I can use kTexture2DPixelFormat_RGB565, is there some way to define that for specific images as you load them rather than just setting the default for all?

Posted 1 year ago #

abitofcode
Moderator

Yep just call setDefaultAlphaPixelFormat when you need to change;

[Texture2D setDefaultAlphaPixelFormat:kTexture2DPixelFormat_RGBA8888];
// Set up loading of RGBA88888

[Texture2D setDefaultAlphaPixelFormat:kTexture2DPixelFormat_RGBA4444];
// Now load RGBA4444's

... etc

Posted 1 year ago #

Webtopia
Member

I thought of that but thought their might have been a neater way.

Very cool though thanks. Should save heaps of space.

Posted 1 year ago #

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