Vulkan: Using main Viewport as Sprite2D texture causing artefacts and error

[abochar]

Godot version

v4.0.alpha6.official [e4f0fc5]

System information

Windows 11, Vulkan, Nvidia 3080Ti (511.79)

Issue description

Using main Viewport as Sprite2D texture causing artefacts and error:

E 0:00:02:0993 draw_list_bind_uniform_set: Attempted to use the same texture in framebuffer attachment and a uniform (set: 3, binding: 0), this is not allowed.
<C++ Error> Condition "attachable_ptr[i].texture == bound_ptr[j]" is true.
<C++ Source> drivers/vulkan/rendering_device_vulkan.cpp:7419 @ draw_list_bind_uniform_set()

Steps to reproduce

Create sprite 2d, assign main viewport texture to it.

Minimal reproduction project

Viewport.zip

[gerrywastaken]

This same error was mentioned in a few places so I want to create a link to them so that people eventually find this issue as it doesn't yet come up on Google:

1. Attempted to use the same texture in framebuffer attachment error #44473 (comment)
2. Viewport doesn't render at default size [512,512] #66483 (comment)
3. https://godotengine.org/qa/132245/trying-shader-based-game-using-same-texture-uniform-allowed
4. https://youtu.be/VSwVwIYEypY?t=377 (clearly shows the error spam - watched by 66K times, not sure how many encountered the same error. The presenter also encountered the 512x512 error )

Also this error still happens in v4 Beta 6

[c-schembri]

This issue is still occurring in 4.0.3.

[wilkie]

Still occurring in 4.1.1 stable. More or less any viewport texture to itself, in order to reference a prior frame. This all works in spite of the message suggesting that it is not allowed. The error spam ends up making the debugger quite useless that I will likely build Godot myself to silence it, which isn't the worst workaround.

[nan0m]

I found a workaround that eliminates the warning.

try this:

var viewport_texture = get_viewport().get_texture()
node.texture = ImageTexture.create_from_image( viewport_texture.get_image() )

the docs mention that you might want to do

await RenderingServer.frame_post_draw

before creating the image texture. Which wasn't necessary for my usecase. But I thought I would still mention it here.

[clayjohn]

Just jumping in here to add some context. Using the root Viewport as a texture to draw a Sprite in the root Viewport is not supported and cannot be supported. The error is correct, but not very helpful for end-users.

What we probably need to do is detect if the user is trying to use the ViewportTexture of the root Viewport and then provide a proper error that this is not supported.

This will of course be tricky as we need to do the same for SubViewports (SubViewports cannot be used as a texture to draw an item that is a child of that SubViewport)