Image effect on performance

games4fun

Hello,

So I have created my images for the ipad size of 1024 by 768 and have placed the images in my iphone project with rentia display and they come out 512 by 384 and then I scale the images further to make then 480 by 320. I was wondering if anyone else does this? Since I have alot of images a total of 60 mb that shows up in the gamesalad viewer yet if you look at they total image file sizes it only equals 11 mb any reason why the viewer shows such a larger amount?

SlickZero

That's how much memory GameSalad is using for the images being displayed, not how large the file size is for them.

File size is irrelevant when it comes to memory needed to display. The memory used to display is based off the images original dimensions. Even though you are re-sizing them lower, each image is still using the amount of memory required to display an image at 1024x768. That's what the 60mb is you are seeing,
is referring to.

games4fun

So im better off resizing the images to iphone sizes first and then reloading images. I assume this has a huge effect on why my app is crashing on the ipod touch 4 and is fine on iphone 4 then. Does image size effect fps?

Thanks

SlickZero

It can. Depends on how many images there are, and if they are moving and whatnot. Stationary images won't really slow your fps, it's when you have lots of movement, and constraints, and timers going on at the same time that lowers fps.

MobileRocketGames

...Even though you are re-sizing them lower, each image is still using the amount of memory required to display an image at 1024x768.

Also, each image uses the amount of memory needed to display an image rounded up to the nearest power of 2 in each vector. So a 1024x768 rectangle actually uses the same amount of memory as it would to display a 1024x1024 square. You could chop up your large images into 4 smaller images (i.e. one 1024x768 could be two 512x512 and two 512x256) but it's a lot more work and not really necessary unless you have a lot of large images on screen at once.

And yes, your best bet would be to resize those images and use the smaller ones when needed. Theres no point using a 2048x1536 iPad 3 background image on a iphone 3gs or 4.

Image size does affect FPS, because they are loaded into memory which means you have less memory left to run everything else. Game filesize does not (only affects loading time directly).