Simple Directmedia Layer
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Sam Lantinga ab06f570a8 Workaround for bug 3931 - spurious SDL_MOUSEMOTION events with SDL_HINT_MOUSE_RELATIVE_MODE_WARP 1 since Windows 10 Fall Creators update
Elis?e Maurer

The attached minimal program sets the SDL_HINT_MOUSE_RELATIVE_MODE_WARP to 1, enables relative mouse mode then logs all SDL_MOUSEMOTION xrel values as they happen.

When moving the mouse exclusively to the right:

 * On a Windows 10 installation before Fall Creators update (for instance, Version	10.0.15063 Build 15063), only positive values are reported, as expected
 * On a Windows 10 installation after Fall Creators update (for instance, Version 10.0.16299 Update 16299), a mix of positive and negative values are reported.

3 different people have reproduced this bug and have confirmed it started to happen after the Fall Creators update was installed. It happens with SDL 2.0.7 as well as latest default branch as of today.

It seems like some obscure (maybe unintended) Windows behavior change? Haven't been able to pin it down more yet.

(To force-upgrade a Windows installation to the Fall Creators update, you can use the update assistant at https://www.microsoft.com/en-us/software-download/windows10)

Eric Wasylishen

Broken GetCursorPos / SetCursorPos based games on Win 10 fall creators are not limited to SDL.. I just tested winquake.exe (original 1997 exe) and it now has "jumps" in the mouse input if you try to look around in a circle. It uses GetCursorPos/SetCursorPos by default. Switching WinQuake to use directinput (-dinput flag) seems to get rid of the jumps.

Daniel Gibson

A friend tested on Win10 1607 (which is before the Fall Creators Update) and the  the bug doesn't occur there, so the regression that SetCursorPos() doesn't reliably generate mouse events was indeed introduced with that update.
I even reproduced it in a minimal WinAPI-only application (https://gist.github.com/DanielGibson/b5b033c67b9137f0280af9fc53352c68), the weird thing is that if you don't do anything each "frame" (i.e. the mainloop only polls the events and does nothing else), there are a lot of mouse events with the coordinates you passed to SetCursorPos(), but when sleeping for 10ms in each iteration of the mainloop, those events basically don't happen anymore. Which is bad, because in games the each iteration of the mainloop usually takes 16ms..

I have a patch now that I find acceptable.
It checks for the windows version with RtlGetVersion() (https://msdn.microsoft.com/en-us/library/windows/hardware/ff561910.aspx) and only if it's >= Win10 build 16299, enables the workaround.
All code is in video/windows/SDL_windowsevents.c
and the workaround is, that for each WM_MOUSEMOVE event, "if(isWin10FCUorNewer && mouseID != SDL_TOUCH_MOUSEID && mouse->relative_mode_warp)", an addition mouse move event is generated with the coordinates of the center of the screen
(SDL_SendMouseMotion(data->window, mouseID, 0, center_x, center_y);) - which is exactly what would happen if windows generated those reliably itself.
This will cause SDL_PrivateSendMouseMotion() to set mouse->last_x = center_x; and mouse->last_y = center_y; so the next mouse relative mouse event will be calculated correctly.

If Microsoft ever fixes this bug, the IsWin10FCUorNewer() function would have to
be adjusted to also check for a maximum version, so the workaround is then disabled again.
2017-12-10 09:17:33 -08:00
VisualC Removed duplicate entry for SDL_wasapi.h 2017-12-08 16:12:53 -08:00
VisualC-WinRT audio: Port WASAPI to WinRT, remove XAudio2 backend. 2017-12-06 12:24:32 -05:00
Xcode Enable building the Metal renderer by default, and weak link the Metal framework so the SDL library is safe to use on older Macs 2017-12-07 16:08:09 -08:00
Xcode-iOS Added the Metal framework to several iOS tests 2017-12-10 09:09:27 -08:00
acinclude Fixed bug 3481 - Configure fails to detect dynamic library support on powerpc64le 2016-11-06 20:26:48 -08:00
android-project Fixed Android build error on older SDK 2017-11-12 10:59:05 -08:00
android-project-ant Added the old ant Android build project structure 2017-10-28 12:11:25 -07:00
build-scripts Fixed typos (thanks Martin!) 2017-12-04 20:21:52 -08:00
cmake vulkan: Include a copy of vulkan.h and vk_platform.h. 2017-08-27 23:25:12 -04:00
debian Updated version to 2.0.8 since SDL_image depends on it 2017-11-04 21:58:48 -07:00
docs audio: Port WASAPI to WinRT, remove XAudio2 backend. 2017-12-06 12:24:32 -05:00
include Added SDL_WinRTGetDeviceFamily() to find out what type of device your application is running on (thanks Daniel Knobe!) 2017-12-10 09:10:02 -08:00
src Workaround for bug 3931 - spurious SDL_MOUSEMOTION events with SDL_HINT_MOUSE_RELATIVE_MODE_WARP 1 since Windows 10 Fall Creators update 2017-12-10 09:17:33 -08:00
test Fixed building YUV test programs (thanks Ozkan!) 2017-11-17 10:54:46 -08:00
visualtest Renaming of guard header names to quiet -Wreserved-id-macro 2017-08-28 00:22:23 -07:00
.hgignore Updated SDL's YUV support, many thanks to Adrien Descamps 2017-11-12 22:51:12 -08:00
Android.mk Updated SDL's YUV support, many thanks to Adrien Descamps 2017-11-12 22:51:12 -08:00
BUGS.txt BUGS.txt: Changed mailing list link to discourse.libsdl.org. 2017-04-01 00:05:25 -04:00
CMakeLists.txt audio: Port WASAPI to WinRT, remove XAudio2 backend. 2017-12-06 12:24:32 -05:00
COPYING.txt Updated copyright for 2017 2017-01-01 18:33:28 -08:00
CREDITS.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
INSTALL.txt More HTTPS doc tweaks. 2017-02-16 16:59:07 -05:00
Makefile.in vulkan: Initial Vulkan support! 2017-08-27 22:15:57 -04:00
Makefile.minimal Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
Makefile.pandora pandora: Fixed compiler warning about redefining SDL_REVISION. 2017-06-18 23:00:27 +02:00
Makefile.psp PSP: Added missing object for generic TLS to Makefile. 2016-02-13 17:34:14 +01:00
Makefile.wiz Pandora: Updated SDL version in Makefile. 2016-07-19 21:01:30 +02:00
README-SDL.txt More HTTPS changes in the documentation. 2017-02-16 16:52:03 -05:00
README.txt readme: correct webpage URL to use HTTPS. 2017-02-16 13:30:34 -05:00
SDL2.spec.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
SDL2Config.cmake Fixed bug 3651 - CMake build does not install CMake package configuration 2017-08-09 19:03:10 -07:00
TODO.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
VisualC.html Fixed two typos in documentation. 2016-01-12 22:23:53 +01:00
WhatsNew.txt Added SDL_WinRTGetDeviceFamily() to find out what type of device your application is running on (thanks Daniel Knobe!) 2017-12-10 09:10:02 -08:00
autogen.sh Don't use pushd/popd in autogen.sh; Ubuntu's /bin/sh doesn't support it. 2016-12-26 22:58:58 -05:00
cmake_uninstall.cmake.in Fixed bug 3867 - Can't find install_manifest.txt when running 'uninstall' target 2017-10-12 08:44:45 -07:00
configure configure: List Metal in video drivers. 2017-12-08 00:49:35 -05:00
configure.in configure: List Metal in video drivers. 2017-12-08 00:49:35 -05:00
sdl2-config.cmake.in Applied Ubuntu patch bug_822210_fix_sdl2-config.cmake_whitespace.patch 2016-10-07 15:08:37 -07:00
sdl2-config.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
sdl2.m4 Fixed bug 3429 - Update AM_PATH_SDL2() to also check for SDL2.framework 2016-09-29 16:37:08 -07:00
sdl2.pc.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00

README.txt

                         Simple DirectMedia Layer

                                  (SDL)

                                Version 2.0

---
https://www.libsdl.org/

Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.

More extensive documentation is available in the docs directory, starting
with README.md

Enjoy!
	Sam Lantinga				(slouken@libsdl.org)