InputEventMouseMotion.Relative is tied to window size

[swift502]

Godot version

v3.3.2.stable.mono.official

System information

Windows 10, GLES3, GTX 1060 3GB 27.21.14.6647

Issue description

I noticed that running my game in windowed mode at 1920x1080 results in noticeably higher mouse sensitivity than running it at 2560x1440.

Turns out the Third Person Shooter Demo suffers from the same issue. I performed roughly the same mouse movements with two different window sizes.

Left: 320x240 window, produces ~360° of camera rotation
Right: 2560x1440 window, produces ~60° of camera rotation

comparison.mp4

• Is this intended behavior?
• Is it not a problem to essentially have mouse sensitivity tied to screen resolution?

Thanks.

Apparent solution

In case it helps, I noticed that multiplying the relative value by the smaller window dimension results in what I percieve as the "correct" behavior, where sensitivity remains constant across different window sizes and aspect ratios.

RotateCamera(@event.Relative); // works poorly

RotateCamera(@event.Relative * Mathf.Min(OS.WindowSize.x, OS.WindowSize.y)); // works much better

Steps to reproduce

1. Use InputEventMouseMotion.Relative to orbit your camera around.
2. Run the game in windowed mode
3. Test mouse sensitivity with different window sizes
4. Test exaggerated aspect ratios, like and extremely wide or tall window, as the incorrect mouse sensitivty becomes even more apparent at those sizes

Minimal reproduction project

Third Person Shooter Demo

[Calinou]

Is this intended behavior?

I don't know if this is intended behavior, but I think relative mouse motion in captured mouse mode should be resolution-independent, regardless of the stretch mode configured. This is how it works in most games after all.

As far as I know, this depends on the configured stretch mode in the Project Settings. Compare the default disabled mode with the 2d stretch mode, then compare it with the viewport stretch mode.

Changing this will require breaking compatibility with existing projects, so it can only be done for 4.0.

[swift502]

this depends on the configured stretch mode

You seem to be right.

• disabled seems to work correctly.
• 2d behaves incorrectly (as seen in the "comparison" video I posted).
• viewport seems to behave roughly the same way as 2d, also incorrectly.

[flouterrr]

I'm still not 100% sure since I haven't looked at the engine code, but I suspected that InputEventMouseMotion.relative is actually tied to the size of the viewport / project width & height.

So after some testing I found that the solution is multiplying the InputEventMouseMotion.relative vector by a ratio of the size of the smaller window side by the corresponding size of the viewport side. That's one hell of a sentence, I'll post the code so that I'll hopefully make more sense.

var mouse_movement : Vector2
	if min(OS.window_size.x, OS.window_size.y) == OS.window_size.x:
		mouse_movement = event.relative * (OS.window_size.x / get_viewport().size.x)
	else:
		mouse_movement = event.relative * (OS.window_size.y / get_viewport().size.y)

I don't know how efficient (or iefficient) it is to have this if else statement run time there is any mouse movement, but it does work, so if anyone has any ideas on how to make this more optimized then the coast's clear.

[Braboware]

I recorded some data in 4.1.1 that may be useful.
Project used for testing
used https://github.com/KovaaK/SensitivityMatcher for windows
and https://github.com/grindzohr/SensMatch for linux
3.0 sens x 0.022 yaw

OS	Viewport Width	Viewport Height	Size Mode	Stretch Mode		rotation_degrees.y, 1 Rotation	rotation_degrees.y, 22 Rotations	Notes
Windows 11	2560 (native)	1440 (native)	Windowed	disabled		-0.0299999062	0.0000409813365	On target
Windows 11	2560 (native)	1440 (native)	Windowed	canvas_item		-4.809093475	-106.6027145
Windows 11	2560 (native)	1440 (native)	Windowed	viewport		-4.875981808	-106.6026764
Windows 11	2560 (native)	1440 (native)	Fullscreen	disabled		0.03600022942	0.00001451422577	On target
Windows 11	2560 (native)	1440 (native)	Fullscreen	canvas_item		-0.593421638	-12.39433098
Windows 11	2560 (native)	1440 (native)	Fullscreen	viewport		-0.5273184776	-12.39431095
Windows 11	2560 (native)	1440 (native)	Exclusive Fullscreen	disabled		0.03600022942	0.0000589106312	On target
Windows 11	2560 (native)	1440 (native)	Exclusive Fullscreen	canvas_item		-0.0299999062	0.00002646711255	On target
Windows 11	2560 (native)	1440 (native)	Exclusive Fullscreen	viewport		0.03600022942	0.00006061821477	On target
Windows 11	640	480	Windowed	disabled		0.03600022942	0.0000409813365	On target
Windows 11	640	480	Windowed	canvas_item		-0.0299999062	0.00005549551497	On target
Windows 11	640	480	Windowed	viewport		0.03600022942	0.00002646712164	On target
Windows 11	640	480	Fullscreen	disabled		-0.0299999062	0.00005549550406	On target
Windows 11	640	480	Fullscreen	canvas_item		-120.1757736	-124.1312561
Windows 11	640	480	Fullscreen	viewport		-120.1978073	-124.1312714
Windows 11	640	480	Exclusive Fullscreen	disabled		0.03600022942	0.00001451422577	On target
Windows 11	640	480	Exclusive Fullscreen	canvas_item		-120.0100021	-120.0000763
Windows 11	640	480	Exclusive Fullscreen	viewport		-120.0100021	-120.0000992
Kubuntu 23.04	2560 (native)	1440 (native)	Windowed	disabled		-0.0299999062	-0.6599736214	On target
Kubuntu 23.04	2560 (native)	1440 (native)	Windowed	canvas_item		-22.75618935	-140.6360779
Kubuntu 23.04	2560 (native)	1440 (native)	Windowed	viewport		-22.75619316	-140.6360016
Kubuntu 23.04	2560 (native)	1440 (native)	Fullscreen	disabled		-0.02998282574	-0.6598005891	On target
Kubuntu 23.04	2560 (native)	1440 (native)	Fullscreen	canvas_item		-0.02998624183	0.6597261429	On target
Kubuntu 23.04	2560 (native)	1440 (native)	Fullscreen	viewport		-0.02999136411	-0.659752965	On target
Kubuntu 23.04	2560 (native)	1440 (native)	Exclusive Fullscreen	disabled		-0.0299999062	-0.6599736214	On target
Kubuntu 23.04	2560 (native)	1440 (native)	Exclusive Fullscreen	canvas_item		-0.0299999062	-0.659974277	On target
Kubuntu 23.04	2560 (native)	1440 (native)	Exclusive Fullscreen	viewport		-0.0299999062	-0.6599736214	On target
Kubuntu 23.04	640	480	Windowed	disabled		-0.0299999062	-0.6599736214	On target
Kubuntu 23.04	640	480	Windowed	canvas_item		-0.0299999062	-0.6599736214	On target
Kubuntu 23.04	640	480	Windowed	viewport		-0.0299999062	-0.6599736214	On target
Kubuntu 23.04	640	480	Fullscreen	disabled		-0.0299999062	0.6599736214	On target
Kubuntu 23.04	640	480	Fullscreen	canvas_item		-120.0100021	-120.2200623
Kubuntu 23.04	640	480	Fullscreen	viewport		-120.0319977	-120.2200623
Kubuntu 23.04	640	480	Exclusive Fullscreen	disabled		0.0299999062	-0.6599713564	On target
Kubuntu 23.04	640	480	Exclusive Fullscreen	canvas_item		-120.0100021	-120.2200623
Kubuntu 23.04	640	480	Exclusive Fullscreen	viewport		-120.0100021	-120.2200623

[Calinou]

Thanks for the report! Consolidating in #34805, as this is due to the same cause.