iOS uses more RAM than other platforms when using large AtlasTextures

[Valeryn4]

Godot version: 3.2

OS/device including version: IOS (iphone 6, iphone x)

Issue description:
Im use big atlas 2048x2048, LOSSY 0.7
IOS uses too much memory.
More than android and windows
I do not like the fact that applications on iOS (arm, arm64, x86, x86_64) weigh minimum ~40 mb
(*.a file weight 193mb, all arch)
p.s. andoid apk size min ~15-20mb

android ~200mb peak (Im used cat /adb shell "cat /proc/meminfo")

windows ~190mb

apple in xcode ~300mb (Memory warnings appear)

[Calinou]

Im use big atlas 2048x2048, LOSSY 0.7

Lossy (= WebP) image compression will still upload the image uncompressed to the GPU, so high memory is usage is expected. In other words, lossy compression only helps decrease the amount of storage space required for the texture.

You need to use VRAM compression to decrease memory usage. It seems that on iOS, only PVRTC is available; you need to encode it manually using the reference PVRTC encoding tool.

[volzhs]

are you using one big atlas?
I'm using many big images for my project with lossy but I didn't have a problem even with 5s.
the project is running on 3.1 though.

[Valeryn4]

are you using one big atlas?

nope...
Several large(5-6 2048x2048) and many small (10-15 512x512-1024x1024)

IOS uses memory more than other platforms

[volzhs]

it would be better not to use atlas if you can then.
but, yeah, still need to know why iOS requires more than others.

[HEAVYPOLY]

Same behavior here, except more extreme.

iOS - 1.18GB
Windows, Android ~ 550mb

Getting memory crash on Xcode.

[Calinou]

@Valeryn4 @HEAVYPOLY Please upload a minimal reproduction project to make this easier to troubleshoot.

[HEAVYPOLY]

@Calinou https://www.dropbox.com/sh/tb5zoez4mih6h45/AABrDG5lPFTu15L8mz33Fr5Ca?dl=0 here's the project, open the autosave.hp from top left hamburger file menu (or draw a bit and compare memory consumption). You can press N to create new layers which will accentuate the difference.

On an empty canvas with 1 screenshot of the viewport (1920X1920 viewport size):

iOS - 400mb
Android - 54MB

Same setup without the screenshot:
iOS 382mb
Android - 26MB

screenshot method:
var img: Image = VP.get_texture().get_data()
img.lock()
var tex = ImageTexture.new()
tex.create_from_image(img, 0)
return tex

I've tried turning on PRTVC compression in project settings, importing all textures with VRAM compression, and built Godot and export templates from commit e9a8e1a1 from today

[Calinou]

I've tried turning on PRTVC compression in project settings

If you enable PVRTC in the project settings, you also have to specify the path to the command line Imagination Technologies PVRTC encoder in the Editor Settings. This is because Godot doesn't include a PVRTC encoder. Otherwise, textures will still be uncompressed in the final project.

That said, PVRTC support was broken before 3.2.4beta3.