[SDL] Incorrect mouse position while pressed some key

Marek Rosa marekrosa at stonline.sk
Wed Sep 4 13:41:01 PDT 2002

I am using SDL 1.2.4, downloaded 8/31/2002.


> I had a similar problem with mouse coordinates under the OpenGL renderer,
> but it was fixed in SDL v1.2.4.  What version of SDL are you using?

> -- Jeff

> "Marek Rosa" <marekrosa at stonline.sk> wrote in message
> news:mailman.1031085122.29836.sdl at libsdl.org...
>> Hello,
>> we think, that we have found an error in getting mouse position in Win32
>> applications, running OpenGL and SDL.
>> Sample app with source code can be downloaded from
>> www.freex.sk/sdl/sdl_mouse_problem.rar This sample app is minimal
> implemetation
>> we have made to show this error.
>> When yor run the app, and move mouse, circle in window will move. It's
>> OK. But when you press some key on keyboard, for example "e", the mouse
>> will move in skips.
>> It's because when we get relative mouse position through
>> SDL_GetRelativeMouseState() - with pressed key "e" on keyboard, the
>> relative positons will skip from small numbers to high numbers, for
>> example: 3, 3, 3, 90 in each frame. Try it. In console windows we are
>> logging this numbers, so you can see.
>> This problem doesn't exist, when SDL_ShowCursor(SDL_ENABLE). But we
>> want do hide default mouse cursor.
>> This problem exists in windowed and fullscreen apps too.
>> This problem occures only in small FPS, or when there is a lot of
>> rendering. I tried to simulate this by SDL_Delay(100) in main loop.
>> But in our main application, it's slowed by rendering code, so this is
>> only simulation of real delaying.
>> Tested on:
>>   Windows 2000, SP2
>>   Visual C++ 6.0 SP5
>>   SDL 1.2.4, downloaded 8/31/2002
>> Thanks for any help,
>> Marek Rosa

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