Textures created with `ImageTexture.create_from_image` are ignoring custom provided mipmaps

[Zylann]

Godot version

Godot 4 beta2

System information

Windows 10 64 bits NVIDIA GeForce GTX 1060

Issue description

I created an Image from code, integrating custom mipmaps. The image is successfully created, however when I use it to create an ImageTexture, the resulting texture appears to have no mipmaps.

Steps to reproduce

	var im = Image.new()
	im.create_from_data(size_x, size_y, true, Image.FORMAT_RGB8, pixels_with_mipmaps)
	var tex = ImageTexture.create_from_image(im)
	var sm = ShaderMaterial.new()
	sm.shader = load("res://show_mips.gdshader")
	sm.set_shader_parameter("u_texture", tex)
	_mesh_instance.material_override = sm

shader_type spatial;

uniform sampler2D u_texture;

void fragment() {
	ALBEDO = textureLod(u_texture, UV, fract(TIME) * 10.0).rgb;
}

Minimal reproduction project

ImageMipmaps.zip

In this project, every mip is a different random color. The expected result is a cube flickering with multiple colors. However only the first color shows up.

I'm not sure yet if I've done a mistake somewhere, because the way to create custom mipmaps is not documented, mipmaps aren't shown in editor inspector, and currently the remote inspector doesn't seem to work well enough to show remote textures.

After giving mipmaps to icon.png and testing this:

var tex = ImageTexture.create_from_image(load("res://icon.svg").get_image())

The result appears to have mipmaps. So I'm quite confused what I could have possibly missed.
Maybe Image isn't properly initializing? Maybe mipmaps I provide are completely ignored?

After more tests (adding noise to mip colors) it seems the latter is happening... ImageTexture finds that there are mipmaps, but ignores them and makes its own.

[bitsawer]

Custom mipmaps should work as I use some in my project. It looks like the error is here:

var im = Image.new()
im.create_from_data(size_x, size_y, true, Image.FORMAT_RGB8, pixels)

That probably should be:

var im = Image.create_from_data(size_x, size_y, true, Image.FORMAT_RGB8, pixels)

as Image.create_from_data() is now a static function. After this, the demo project shows some colors. I was struggling with custom mipmaps too and just created this PR to make handling them a bit easier: #74142.

[Zylann]

Fixing the static call to create_from_data does not fix the issue. Colors are not changing in Godot 4.0 stable.

Updated project:
ImageMipmaps.zip

Note, I included a randomization of the R component to show that mipmaps are cycling, because Godot is generating mipmaps, just not using those I provide.

[bitsawer]

Interesting. I can actually see some very subtle mipmap noise animation in that updated project. But try changing to Compatibility renderer and things start to work somewhat. Maybe a bug somewhere in Vulkan renderer?

Also, changing:

var pixel_size = 3 to var pixel_size = 4 and FORMAT_RGB8 to FORMAT_RGBA8 also seems to fix something and makes things work in Forward+ renderer, too.

[bitsawer]

Could be that some of these image->convert() calls might cause this, as they also regenerate mipmaps from the topmost image and discard custom mipmaps. The fix might be to convert each mipmap individually.

godot/servers/rendering/renderer_rd/storage_rd/texture_storage.cpp

Lines 1468 to 1481 in 1c1524a

	//this format is not mandatory for specification, check if supported first
	if (false && RD::get_singleton()->texture_is_format_supported_for_usage(RD::DATA_FORMAT_R8G8B8_UNORM, RD::TEXTURE_USAGE_SAMPLING_BIT | RD::TEXTURE_USAGE_CAN_UPDATE_BIT) && RD::get_singleton()->texture_is_format_supported_for_usage(RD::DATA_FORMAT_R8G8B8_SRGB, RD::TEXTURE_USAGE_SAMPLING_BIT | RD::TEXTURE_USAGE_CAN_UPDATE_BIT)) {
	r_format.format = RD::DATA_FORMAT_R8G8B8_UNORM;
	r_format.format_srgb = RD::DATA_FORMAT_R8G8B8_SRGB;
	} else {
	//not supported, reconvert
	r_format.format = RD::DATA_FORMAT_R8G8B8A8_UNORM;
	r_format.format_srgb = RD::DATA_FORMAT_R8G8B8A8_SRGB;
	image->convert(Image::FORMAT_RGBA8);
	}
	r_format.swizzle_r = RD::TEXTURE_SWIZZLE_R;
	r_format.swizzle_g = RD::TEXTURE_SWIZZLE_G;
	r_format.swizzle_b = RD::TEXTURE_SWIZZLE_B;
	r_format.swizzle_a = RD::TEXTURE_SWIZZLE_ONE;

[Zylann]

Interesting. I can actually see some very subtle mipmap noise animation in that updated project

This is

Note, I included a randomization of the R component to show that mipmaps are cycling, because Godot is generating mipmaps, just not using those I provide.