Vulkan: Viewport's keep_3d_linear property not reimplemented yet

[Calinou]

Godot version: Git 4e52c75

OS/device including version: Fedora 31, GeForce GTX 1080 (NVIDIA 440.100)

Issue description: Viewport's keep_3d_linear property hasn't been reimplemented yet in the Vulkan renderer. That property is available in 3.2.2.

Steps to reproduce: Search for keep_3d_linear in the editor help.

Minimal reproduction project: N/A

[clayjohn]

I think reduz intentionally got rid of it. I remember discussing this when he was first making the Vulkan Renderer.

[thunderk]

The hdr property is gone too, I guess they are related.

A potential use-case for these properties is to bake an HDRi panorama sky from a scene, by using HDR-enabled viewports.

[Calinou]

The hdr property is gone too, I guess they are related.

A potential use-case for these properties is to bake an HDRi panorama sky from a scene, by using HDR-enabled viewports.

HDR is now always enabled in viewports. Unlike GLES3 in 3.x, there is no way to disable HDR in the Vulkan renderer.

[thunderk]

Oh sorry, I thought the viewport was not HDR-enabled because the texture I retrieved from it was in RGBA8 format. I created another issue #54122 regarding this, as it's not really related.

[SmartySmart702]

Is there a replacement or workaround? I need this for portals and right now the colors are off.

[Calinou]

Is there a replacement or workaround? I need this for portals and right now the colors are off.

You should be able to implement sRGB-to-linear or linear-to-sRGB conversion in the shader displaying the portal texture (on the ALBEDO color). The formulas for doing this are well-known:

godot/drivers/gles3/shaders/cubemap_filter.glsl

Lines 50 to 56 in a6ed558

	vec3 linear_to_srgb(vec3 color) {
	return max(vec3(1.055) * pow(color, vec3(0.416666667)) - vec3(0.055), vec3(0.0));
	}
	vec3 srgb_to_linear(vec3 color) {
	return color * (color * (color * 0.305306011 + 0.682171111) + 0.012522878);
	}

[clayjohn]

Will be fixed by #70970 in 4.1

[RichMakeGame]

it would be fantastic to see this feature re-added, the conversion workaround is causing issues for my use case with the loss of precision

[RichMakeGame]

is there any other workaround for uses where viewport texture is being used for alternative purposes? converting back to linear bunches all the precision toward 0 and values approaching 1 are too 'chunky'

[Arnklit]

I have been dealing with this issue for getting my addon Waterways running correctly in Godot 4.x and I hadn't been able to get it work work no matter what conversions I did.

I realised it was because tonemapping was playing into it as well. if you don't have a environment inside your viewport, it will use an external one or a default one with filmic tonemapping. Be sure to make an environment with linear tonemapping inside your viewport.

Also it appears that the "Use HDR 2D" setting works with 3D and keeps it linear as well now. you just still have to ensure no tonemapping is happening.