Allow texture preview to zoom and popout in separate window

[Arnklit]

This adds a button that opens the preview in a popup and adds zoom controls. Resolves godotengine/godot-proposals#10160.

EDIT: Original video, before I added zoom, see video in comment for the current behavior

godot.windows.editor.dev.x86_64_jTxo9h7JiQ.mp4

[Arnklit]

Got a bit inspired and had a go at adding zooming to the preview as well. The code is probably a bit rough now, so I'm setting it to draft until I've done a review of it myself.

godot.windows.editor.dev.x86_64_JKHTVewkqO.mp4

[Arnklit]

Rebased and reworked with the new LOD selector. Ready for review.

godot.windows.editor.dev.x86_64_PIgfdd0NOB.mp4

@DDarby-Lewis I ended up moving the LOD selector you added in to the other side and I limited it's width to 2 digits, let me know what you think.

[Arnklit]

Sorry, there was some ugly snafu in my git actions that closed the PR. should be back in order now.

[Arnklit]

Note I believe there was a bug in #109004
The preview shader used the texture function and set the lod bias, rather than the textureLod which sets the LOD directly. I changed that over as part of these changes, but maybe it should be put in a separate PR.

[DDarby-Lewis]

@Arnklit good catch on the texturelod function, I think fixing it here is good, and I'm happy with the lod selector change :)

[Arnklit]

Rebased

[Calinou]

Tested locally (rebased on top of master 321b8c9), it works as expected.

Some feedback:

• The speed at which you pan doesn't match the mouse cursor movement, which feels odd. Panning is much faster than expected, especially at higher zoom levels.

• It should be possible to pan the view with the middle mouse button, for consistency with the 2D editor viewport.

• Zooming in at higher levels feels less impactful, as the zoom percentage is increased linearly (e.g. going from 400% to 410% is a much lower increase than going from 100% to 110%). I would look at how the 2D editor viewport handles zoom for inspiration, as it uses nonlinear scaling for scroll wheel zoom to ensure it feels consistent across zoom levels.

• At the minimum width, the mipmap and zoom indicators can overlap:

This can also occur in the inspector if it's made narrow enough, especially if the channel indicator is also visible. This is roughly the minimum width required for them to not overlap:

[Calinou]

I see the channel selector in the top-left corner, just like in the inspector:

Suggested change

	// Add color channel selector at the bottom left if more than 1 channel is available.
	// Add color channel selector at the top-left corner if more than 1 channel is available.

[KoBeWi]

You should use ViewPanner for panning, instead of implementing it manually.

[QbieShay]

I think this is useful functionality. I'm particularly fond of the per-channel view.

I tested the PR, and I have some UX comments:

It's a bit hard to understand whether some channels are active or not. I suggest using the same scheme as the 3d view:

I would also suggest 2 more buttons for the channel: RGB, RGBA. RGBA is selected by default. RGB shows RGB without A
Clicking RGB is exclusive with RGBA and exclusive with per-component, while components stay non-exclusive with one another.

Would it be possible to use the whole space to pan and zoom? it feels very wasteful to have all that lateral space unused.

I would also label the MIP button. I would not completely disable it when there's no mipmap, i would just leave it there with disabled buttons. Alternatively, the up button is active but clicking it shows an error message that asks the user to enable mip if they want more mip.

[Arnklit]

Thanks for the feedback @AThousandShips and @Calinou . I'll submit fixes for those issues soon. @KoBeWi I did not realise there was a helper class for exactly that, makes sense. I'll have a go at moving over to that.

@QbieShay I didn't add the channel selectors and mipmap selectors, they are already in master, I just had to adjust them a bit to accomodate the UI. And I had to make sure they worked in the popped out preview.

[QbieShay]

What about the zooming rect using the whole space?

[Arnklit]

What about the zooming rect using the whole space?

Yeah I think that should be doable. I'm trying to rewrite it to use the ViewPanner now and that kind of changes the entire structure of the thing. I'll see if I can make that work.