Vulkan: Alpha channel not included in Viewport capture due to SCREEN_TEXTURE and DEPTH_TEXTURE not being updated

[supagu]

Godot version: Vulkan

OS/device including version: Linux/Arch/Manajro

Issue description: I have a ViewportContainer with a Viewport child to render something in the viewport. I have a custom ShaderMaterial applied to the ViewportContainer
with some code like this:

shader_type canvas_item;

uniform float width: hint_range(0.0, 10.0);
//uniform vec4 color: hint_color;

void fragment() {
	vec4 c = texture(TEXTURE, SCREEN_UV, 0.0);
        COLOR=c.aaaa;
}

the texture always comes out white.

what I am rendering in the viewport is a mesh with a material that is like so:

so that it draws in the alpha channel.

this worked fine when in the godot 3.2 branch and seems to have broken when I try it in Vulkan branch,

[supagu]

Additionally, I tried setting the environment clear color to (0, 0, 0, 0) but still all I see is white in the alpha channel.

[supagu]

in fact any work I have tried to do with capture texture/depth capture has not worked well.

[briansemrau]

This issue is still relevant as of 7a31baf. After experimenting with spatial materials, it appears that SCREEN_TEXTURE and DEPTH_TEXTURE are not being updated with the new Vulkan renderer, resulting in texture calls returning a default value.

@Calinou Maybe this issue should be renamed and possibly labeled as a regression?

[flakusha]

This issue still exists.
Shader which does work correctly in Godot 3.2.3 does not capture SCREEN_TEXTURE in Godot 4 dev 94e5f66

[Calinou]

This appears to be fixed as of 4.0.rc2, closing.

Testing project: test_shader_viewport.zip
(UV is used instead of SCREEN_UV for sampling, but it that's purely for cosmetic reasons.)