CanvasItem.draw_polyline does not draw 1px lines when width<=1.0

[briansemrau]

Godot version:

4.0 7195f6b

OS/device including version:

Vulkan

Issue description:

Following changes in 3ec972f, support for drawing thin lines with draw_polyline seems to have been removed. I believe this is in error.

Using the code:

func _draw():
	draw_arc(Vector2(0, 0), 50, 0, PI * 0.75, 25, Color.white)

when zoomed in, the line should be 1px wide, but it looks like this:

Steps to reproduce:
See above

Minimal reproduction project:

[briansemrau]

@Chaosus

[Calinou]

This may actually be intended, see godotengine/godot-proposals#1363.

We should support both use cases but we probably have to find another way to do that. I think scaling 1-pixel lines by default is a better idea, but there should still be a way to draw "hairline" width lines that don't scale with the viewport.

[briansemrau]

I do agree that width=1 shouldn't create pixel-thin lines and I generally prefer the behavior demonstrated in this issue. Hairline width I think would be better implemented with width=0, not 1. (The solution in the proposal is better). However, right now this function is inconsistent with other line drawing functions and behaves unexpectedly.

[Chaosus]

I think adding the add_thin_polyline method family is not a bad idea. So instead of draw_arc, you would write draw_thin_arc.

But if this is not desired I can restore it to the old state.