A few questions about the best practices.

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A few questions about the best practices.

(7 posts) (4 voices)

Started 2 years ago by ob1
Latest reply from DeeNiri

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ob1
Member

Sorry I am a noob, but I don't understand everything in the best pratices. Even with my gfx artist we disagree on what some of the points mean.

> Use AtlasSprite instead of Sprite

Is it true for any Sprite ? Like, should my background image be an AtlasSprite ? Do I get better performance by tiling my bg image instead of having a big texture ?

> When possible, try to use 4-bit or 16-bit textures
> 16-bit textures for PNG/GIF/BMP/TIFF images

Is it 16-bit total or 16-bit per channel ? Have 4 and 16 the same effect or is one better ? Does is mean I must not use 4-bit for PNG/GIF/BMP/TIFF images ?

> [Texture2D setDefaultAlphaPixelFormat:kTexture2DPixelFormat_RGBA4444]; // add this line at the very beginning

Is that 4 or 16 ? What is the default mode if I don't do use this line ?

> 4-bit or 2-bit textures: Try to use PVRTC textures.

I am not quite sure what this means and what's the relation between my image file and the final texture format.

> Use 32-bit textures as the last resort

What does "last resort" mean in that case? That I really want some shiny stuff or is it something technical in nature?

> Reducing Memory
> Use 16-bit or 4-bit textures (see Improving performance)

Do both give the same result? Is one better? Is that something I set in my PNG color depth or is it something programatically set in Cocos?

> Don’t create a big hierarchy of layers. Try to keep them low when possible.

How many is "low" ?

Thanks for the clarifications.

(As you might guess, I am trying to optimize my game and I am pretty puzzled at the moment).

Posted 2 years ago #
Codemattic
Moderator

riq has good post on his blog that may help clear things up re pixel formats:

http://www.cocos2d-iphone.org/archives/61

"How many is "low"?"
Theres no specific number, just lower=better=faster. But if it makes more sense to have a hierarchy, then do that. Theres no definite magic number of layers you cant go over.

Posted 2 years ago #
Clain
Member

Codemattic got me. Anyway, here are some more explanations.

> Use AtlasSprite instead of Sprite

Is it true for any Sprite ? Like, should my background image be an AtlasSprite ? Do I get better performance by tiling my bg image instead of having a big texture ?

I don't think it's true for any sprite. If your bg is a single image, Sprite and AtlasSprite should have the same performance. AtlasSprite is better than Sprite in the sense that you can put several sprites inside an atlas (thus you end up with a big image file instead of a lot of small ones, which uses less RAM) and the AtlasSpriteManager makes far less openGL calls to draw all its AtlasSprite than any other CocosNode would require to draw the same number of Sprites (it's kind of a batch node).
If I understand correctly the way the iPhone (not the 3GS) GPU renders graphics, tiling the bg image should give you a better performance. But I think it should be very very slight and not worth the trouble (but I could be wrong).

> When possible, try to use 4-bit or 16-bit textures
> 16-bit textures for PNG/GIF/BMP/TIFF images

Is it 16-bit total or 16-bit per channel ? Have 4 and 16 the same effect or is one better ? Does is mean I must not use 4-bit for PNG/GIF/BMP/TIFF images ?

It's 16-bit per pixel (bpp). 4 and 16 don't have the same effect. 16 bpp images are 4 times bigger (in memory) than 4 bpp images. But 4 bpp ones are generally of poor quality. They're used for compressed textures (PVRTC images).

> [Texture2D setDefaultAlphaPixelFormat:kTexture2DPixelFormat_RGBA4444]; // add this line at the very beginning

Is that 4 or 16 ? What is the default mode if I don't do use this line ?

setDefaultAlphaPixelFormat:kTexture2DPixelFormat_RGBA4444 is 16 bpp. You should read this post by Riq : understanding pixel format in cocos2d v0.7.3

> Use 32-bit textures as the last resort

What does "last resort" mean in that case? That I really want some shiny stuff or is it something technical in nature?

In this case, "last resort" mean if you have images that requires that much quality otherwise they don't look good enough (if you a gradient between two close colors for example).

> Reducing Memory
> Use 16-bit or 4-bit textures (see Improving performance)

Do both give the same result? Is one better? Is that something I set in my PNG color depth or is it something programatically set in Cocos?

see previous link to Riq's post

> Don’t create a big hierarchy of layers. Try to keep them low when possible.

How many is "low" ?

I'd like to know that as well. I made some prototype for a match-3 game a few weeks ago. I had 11 layers and things were running smoothly. But most of my layers contained just one sprite or two. So it may not be significant.

Posted 2 years ago #
ob1
Member
Thank you very much. I still have a few questions though.

Here is my situation. My game is pretty okay but has two problems, performance jumps all the time between 40 and 60 FPS making the game a bit choppy (but I don't really now where to look). The background image and clipping image look a bit crappy because of their gradient.

Here is how my layers are setup:

- Background (full screen)
- Sprite layer (like a hundred of small sprites)
- Clipping layer (full screen, basically the background again with a hole in the middle for the sprites).
- Color Layer
- UI 1 (a few sprites)
- UI 2 (a few sprites)

What's the best way to optimize this ? Does it cause more performance loss if the clipping layer is 32bpp ?
```
[Texture2D setDefaultAlphaPixelFormat:kTexture2DPixelFormat_RGBA8888];
Sprite *sprite1 = [Sprite spriteWithFile:@"test-rgba1.png"];
```
Does it need to be done when creating the sprite like here or when loading the texture ?
Posted 2 years ago #
DeeNiri
Member

@ob1: Are you calling [[TextureMgr sharedTextureMgr] removeAllTextures]; in your dealloc method? If you don't, your images may caching, hogging tons of memory, and causing your performance to vary.

I noticed that none of the images I created were being freed from memory (even though I was deallocating the scenes successfully). Once I put [[TextureMgr sharedTextureMgr] removeAllTextures]; in my dealloc method, I noticed a great improvement in my game with zero variations in performance. I am using 24-bit pngs in my game. I'm using cocos2d 0.7.3 for iPhone 3.0.

Posted 2 years ago #
ob1
Member

Hmmm Doesn't removeAlltextures negate the whole point of preloading textures at the beginning of the game or am I mistaken ?

My slowdown problems were due to too many layers and clipping affecting performance.

Posted 2 years ago #
DeeNiri
Member

@ob1: You are correct. I had just solved my image caching issue and thought you might have been affected by the same issue. Please disregard.

Posted 2 years ago #

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