Repository: godotengine/godot (language: cpp)

Issue:
Normal Map (RG Channels) import option has no memory difference in UI
### Tested versions

Godot v4.4.dev7

### System information

Godot v4.4.dev7 - Windows 10 (build 19045) - Single-window, 1 monitor - OpenGL 3 (Compatibility) - NVIDIA GeForce RTX 4050 Laptop GPU (NVIDIA; 32.0.15.6070) - 13th Gen Intel(R) Core(TM) i5-13500HX (20 threads)

### Issue description

According to docs:
https://docs.godotengine.org/en/stable/tutorials/assets_pipeline/importing_images.html
`A third option Normal Map (RG Channels) is only available in layered textures ([Cubemap](https://docs.godotengine.org/en/stable/classes/class_cubemap.html#class-cubemap), [CubemapArray](https://docs.godotengine.org/en/stable/classes/class_cubemaparray.html#class-cubemaparray), [Texture2DArray](https://docs.godotengine.org/en/stable/classes/class_texture2darray.html#class-texture2darray) and [Texture3D](https://docs.godotengine.org/en/stable/classes/class_texture3d.html#class-texture3d)). This forces all layers from the texture to be imported with the RG color format to reduce memory usage, with only the red and green channels preserved. This only has an effect on textures with the VRAM Compressed or Basis Universal compression modes.`

It says memory usage will be reduced. However, this doesn't appear to have any difference because the Memory value shown does not change:

RG:

![Image](https://github.com/user-attachments/assets/c02314d0-53b3-43e8-81d2-2ad5e43dde75)

RGBA:

![Image](https://github.com/user-attachments/assets/2bb4d174-5f53-4334-a69f-7324c1c0b116)


I would expect it to display a lower value.

### Steps to reproduce

Import any layered texture and change the compression to Basis Universal, then set the channel pack to RG mode. Notice that changing the channel back makes no difference in the memory size.

### Minimal reproduction project (MRP)

n/a


Discussion / hints:
The same also applies to the Normal Map import option for Texture2D.
This is what I am seeing under `Compress > Normal Map`

> In the example below, the normal map with RGTC compression is able to preserve its detail much better, while using the same amount of memory as a standard RGBA VRAM-compressed texture:

Which is accurate. RGTC takes the same amount of space as the other compressed options

_Edit: Oh I see, this is under [`Compress > Channel Pack`](https://docs.godotengine.org/en/stable/tutorials/assets_pipeline/importing_images.html#compress-channel-pack) not "Normal Map". It should be clarified to specify that it increases quality at the same memory usage rather than saying it decreases memory usage_
Unless I misunderstood, this is a documentation change not a code change so I updated the docs with the text from the Normal Map section.

Also, first contribution to Godot! 😁

Fix patch:
diff --git a/doc/classes/ResourceImporterLayeredTexture.xml b/doc/classes/ResourceImporterLayeredTexture.xml
index e1e8ee710d0e..f69c44e29bd5 100644
--- a/doc/classes/ResourceImporterLayeredTexture.xml
+++ b/doc/classes/ResourceImporterLayeredTexture.xml
@@ -14,7 +14,7 @@
 			Controls how color channels should be used in the imported texture.
 			[b]sRGB Friendly:[/b], prevents the RG color format from being used, as it does not support sRGB color.
 			[b]Optimized:[/b], allows the RG color format to be used if the texture does not use the blue channel. This reduces memory usage if the texture's blue channel can be discarded (all pixels must have a blue value of [code]0[/code]).
-			[b]Normal Map (RG Channels):[/b] This forces all layers from the texture to be imported with the RG color format to reduce memory usage, with only the red and green channels preserved. This only has an effect on textures with the VRAM Compressed or Basis Universal compression modes. This mode is only available in layered textures ([Cubemap], [CubemapArray], [Texture2DArray] and [Texture3D]).
+			[b]Normal Map (RG Channels):[/b] This forces all layers from the texture to be imported with the RG color format, with only the red and green channels preserved. RGTC (Red-Green Texture Compression) compression is able to preserve its detail much better, while using the same amount of memory as a standard RGBA VRAM-compressed texture. This only has an effect on textures with the VRAM Compressed or Basis Universal compression modes. This mode is only available in layered textures ([Cubemap], [CubemapArray], [Texture2DArray] and [Texture3D]).
 		</member>
 		<member name="compress/hdr_compression" type="int" setter="" getter="" default="1">
 			Controls how VRAM compression should be performed for HDR images.


Test patch: