Trying to port a shader-based game, but using the same texture in a uniform is not allowed

Question

I tried to port a bricks game implemented by iq on shadertoy that works entirely with the GPU to godot, but I ran into difficulties. I don't understand why I can't use the viewport texture like this.

E 0:00:02:0587 draw_list_bind_uniform_set: Attempted to use the same texture in framebuffer attachment and a uniform (set: 1, binding: 1), 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()

I have uploaded the project files to the github repository, would anyone like to help me?

https://github.com/HK-SHAO/GodotBricksGameShader

The game in shadertoy: https://www.shadertoy.com/view/MddGzf

Here is my computer configuration and godot version information.

Godot version

Godot Engine v4.0.alpha6.official.e4f0fc50f

System information

Windows 11, Vulkan API 1.2.0 - Using Vulkan Device #0: NVIDIA - NVIDIA GeForce RTX 3070 Ti Laptop GPU

Comments

Godot 4 is still in alpha. Have you tried in Godot 3? If it works in Godot 3 and not in Godot 4 then it's probably a bug.

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Thanks, I'll give it a try.
But I'd like to know if there's a better way for the fragment shader to get the sampler2D of the previous frame, similar to the backbuffer in glsl.

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Make sure to add a thumbs up to the issue, so that the devs know people are impacted by it:
https://github.com/godotengine/godot/issues/60475#issue-1213362947