image scale and memory usage?

Solar2D General Questions/Discussion
#1

I got into a problem where I am loading many images into memory in 1 scene in my app.

It works ok on iPad2 but not the new one, due to memory issues with the high resolution images. I only own an iPad 2 for testing, the app was rejected after being tested on new iPad due to memory issues, but I cannot test it myself.

I am not sure how to work around that.

1 option I imagine is to use the low resolution versions of the images that work on IPad2 and just scale them up 2x so it fills screen on new iPad, just with lower IQ.
But I wonder if scale by 2 reduces memory usage by 2 or does scaled up image take up same amount of memory (it should but would be good to know for sure)?

How does one do this for just 1 scene in the app so the system of using @2 etc. does not get messed up for all the other scenes?

Would appreciate advice what to do. What do people do with the graphics on retina devices, do they just scale the images in games that are memory-demanding? But how just for some specific images in selected scenes, not others?

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#2

The amount of memory a given image uses is based on it’s original pixel dimensions * 4, but rounded up to the next power of two.

If you have a 640x960 background, it’s actually using 1024x1024x4 (one per RGB color + alpha) which takes up 4 megabytes of texture memory. That same graphic when provided at a 2x size, becomes 1280x1920, which rounds up to a 2048x2048x4 image or 16 megabytes of texture memory, 4 times as much. The Retina iPads have double the memory of the iPad 2, but your graphics are taking up 4 times as much. So if you’re loading quite a few graphics in that once scene, I can see where you might run into memory problems.

The best way to keep the system from loading the @2x graphics is simply don’t provide them. Look for graphics that will still looked good styled up and just leave the @2x version out.
[import]uid: 199310 topic_id: 35764 reply_id: 142279[/import]

#3

The amount of memory a given image uses is based on it’s original pixel dimensions * 4, but rounded up to the next power of two.

If you have a 640x960 background, it’s actually using 1024x1024x4 (one per RGB color + alpha) which takes up 4 megabytes of texture memory. That same graphic when provided at a 2x size, becomes 1280x1920, which rounds up to a 2048x2048x4 image or 16 megabytes of texture memory, 4 times as much. The Retina iPads have double the memory of the iPad 2, but your graphics are taking up 4 times as much. So if you’re loading quite a few graphics in that once scene, I can see where you might run into memory problems.

The best way to keep the system from loading the @2x graphics is simply don’t provide them. Look for graphics that will still looked good styled up and just leave the @2x version out.
[import]uid: 199310 topic_id: 35764 reply_id: 142279[/import]