Godot Version 4.6.3 Question I’m trying to access the texture of a SubViewport’s ViewportTexture from a Compositor in Godot. I am able to link the ViewportTexture to the subview @export variable. However, trying to retrieve and image via get_image returns null. As per the docs , that means the textu…

EDIT: nvm, looks like it possible! check @normalized post below How to access SubViewport in Compositor? - #5 by normalized ▶ Old wrong answer

Subviewports are always rendered before the main viewport. You shouldn’t have any problems accessing subviewport texture from a compute shader. Just pass its RID to the shader as an uniform.

Thank you @mrcdk and @normalized for responding. I believe that I now understand how different render ‘pipelines’ (a pipeline per viewport) is managed at the discretion of the engine. That means a compositor effect, which can modify passes done in a single ‘pipeline’, can’t cross over to other ‘pip…

Thank you @normalized . You’re linked post is quite helpful and pretty applicable to my situation. More specifically, the RenderingServer.texture_get_rd_texture function is good to know. One odd thing that I’ve been trying to figure out is that the viewport texture always appears brighter when proce…

Enabling use_hdr_2d for the subviewport should linearize the texture. Make sure that you’re not doing any srgb/linear conversions elsewhere.

Allow me to clarify my issue. In the below examples, I’ve rendered the real camera on the left half, and the subviewport texture on the right half. When passing srgb = true to RenderingServer.texture_get_rd_texture → [Screenshot 2026-06-15 at 5.48.04 PM] When enabling use_hdr_2d on the subviewp…

What happens if you render the viewport texture through a regular shader?

A similar splitscreen test using gdshader (on a subviewport that has use_hdr_2d = true) will show the correct image (no differences), while use_hdr_2d = false will display similarly to the 3rd image in my previous reply (what i assume is misinterpreting sRGB as linearized). Following images are in …

Using image2D instead of a sampler yields the exact same result unfortunately. If it helps, I made a minimally reproducible version of my code (see below) that still shows the odd behavior of mismatching textures. It includes a gdshader version of the splitscreen, and separate versions of the compo…

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How to access SubViewport in Compositor?

Help Shaders

graphics, godot-4, gdscript

normalized June 15, 2026, 4:03am 5

How can I access the unlit scene in either GDShaders or Compositor for PostProcess effects? Shaders

So here’s the setup. Runs smooth as butter in the editor. I excluded all boilerplate error checks and thread safety stuff for brevity. Once you get it running you can bring all that back in if needed. Editor: [image] Runtime: [image] Scene: [image] Script in scene root (updates camera transform/fov and SubViewport texture rid in compositor effect): @tool extends Node3D func _process(dt) : var vp_main: Viewport if Engine.is_editor_hint(): vp_main = EditorInterface.get_editor_view…

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