Add render size / render scale option

[hhyyrylainen]

Godot has done away with specific fullscreen resolutions. So right now the game resolution is either:

• The window size
• Desktop resolution

Could be fixed with either like a render scale option or a render size option that makes the viewport that Godot renders to smaller.

Edit: for mac this is a very important feature due to retina screens otherwise eating up an absolute ton of rendering power

[athariqk]

Thinking of tackling this one down, but a few questions before that. Should the option lists a preset (assuming it's a dropdown) of predefined screen resolutions e.g 1366x768 or 1920x1080 or does the player manually inputs whatever resolution they want? Also to clarify the option only applies for the viewport size and not the window size right?

[hhyyrylainen]

Well, we can't set the window size anyway. Though I guess in windowed mode we could maybe resize to an exact size if the player wants that.

As for the resolutions I think we should have a preset list that depends on the user's monitor resolution(s) as well as a manual input resolution (where anything is allowed as long as it is bigger than 720p).

As for the render scale we should have like a slider from 30% to 100% (if Godot supports this feature).

[athariqk]

The feature in this PR is worth looking into once 3.4 is out godotengine/godot#52137.