Creating Detail Albedo texture in GDScript causes infinite textures being created.

[Gyrth]

Godot version

v3.4-stable

System information

Manjaro Linux, GLES3, NVIDIA Geforce GTX 1060 495.44

Issue description

In my script I create a detail texture in the _ready function for bullet holes. It works flawlessly but I noticed the object id of the image object increase steadily. So this might be a memory leak, or needless swapping of textures in the engine.

Steps to reproduce

1. Open reproduction project.
2. Run project.
3. Click on the object in Material slot 0.
4. Click the object in Detail Albedo.
5. See the object id of the Image increase.

Minimal reproduction project

BugReport.zip

[Zylann]

I think this is actually a side-effect of remote inspector, I have seen this in the past. It is trying to access image but for some reason I think it re-creates the object client-side just to provide it, but in reality it is not cached.
Similarly if you try to access image in script it might also create a new image each time because it does not actually store such object. Only the data inside is stored. In fact image is not even a documented property, I think it only exists because of serialization purposes.

You can also see some of that in master, the data is cached as a Ref<Image> only in some conditions in editor:

godot/servers/rendering/renderer_rd/renderer_storage_rd.cpp

Lines 1032 to 1040 in ed395c6

	Ref<Image> RendererStorageRD::texture_2d_get(RID p_texture) const {
	Texture *tex = texture_owner.get_or_null(p_texture);
	ERR_FAIL_COND_V(!tex, Ref<Image>());
	#ifdef TOOLS_ENABLED
	if (tex->image_cache_2d.is_valid() && !tex->is_render_target) {
	return tex->image_cache_2d;
	}
	#endif

Then in all the other cases, it gets the data probably from the graphics card or whatever cache if any, but because it gets it as raw bytes, it has to wrap it inside an Image object:

godot/servers/rendering/renderer_rd/renderer_storage_rd.cpp

Lines 1041 to 1044 in ed395c6

	Vector<uint8_t> data = RD::get_singleton()->texture_get_data(tex->rd_texture, 0);
	ERR_FAIL_COND_V(data.size() == 0, Ref<Image>());
	Ref<Image> image;
	image.instantiate();

Which explains why you may get a different instance of an Image object each time.

[Gyrth]

Thank you for checking it out.
So is this considered a bug worth fixing?

[Zylann]

I'm not sure it is even a bug, it looks like it works as intended, as confusing as it looks. I wonder why it shows there in the first place.
Also I have a vague memory that this was raised before, but I can't find the issue if any.

Some other slightly related stuff from the past:
#18801 (comment)