While reviewing my notes, I saw I had written down that TextureRect in Godot uses nearest filtering instead of linear filtering by default and that the only solution was to change the texture_filter value from the baseCanvasItem class.

I remember finding a way to change this by default everywhere in the project; in Godot 4.5.1.stable.arch_linux there's a project setting rendering/textures/canvas_textures/default_texture_filter which can be changed to change the default texture_filter for CanvasItem.

However, it appears that the default is already set to Linear filtering, so I did some digging to see when this was changed. I found that the rendering/textures/canvas_textures/default_texture_filter is also already set to linear in 4.0.stable.

However, 4.0.stable was released on March 1, 2023 ¹ and my note about the default texture filter is from July 22, 2024. My note was written while working on no signal and since I largely kept up to date on Godot versions while working on no signal, I must have been mistaken about Godot's default behavior when I wrote the note.

Checking the VOD when I wrote the note, it seems that at 4h 18m 38s, I changed the filter on the CanvasItem from inherit to nearest and observed no change. This might have been why I made this assumption, though there could be other reasons for why this may have been the case, like the filtering mode having been accidentally set to nearest.

So, to recap, TextureRect in Godot may scale badly due to:

• The TextureRect using the default project setting for rendering/textures/canvas_textures/default_texture_filter, which may be set to a scaling mode you don't like.
• A parent CanvasItem explicitly setting a scaling mode you don't like.

And to fix this, you may need to:

• Change the rendering/textures/canvas_textures/default_texture_filter to the desired texture filter.
• Make sure all CanvasItem parents don't have an explicitly set texture filter, if you want the default texture filter.
• Explicitly change or set the texture_filter value on the respective CanvasItem class (which node you do this to in the tree depends on whether or not each successive parent has inherit as its filter or not).