Raw mouse input with Windows

Question

Reading this article "Taking Advantage of High-Definition Mouse Movement" - http://msdn.microsoft.com/en-us/library/windows/desktop/ee418864(v=vs.100).aspx , I surmise that one should use raw input for more precise readings from input devices.

The article states that WM_MOUSEMOVE's primary disadvantage is that it is limited to the screen resolution.

Upon close inspection of the RAWMOUSE structure I see that lLastX and lLastY are long values and you get the delta via them.

To me it looks like WM_MOUSEMOVE and WM_INPUT is the same except with WM_INPUT you do not get acceleration (pointer ballistics) applied.

Are both WM_MOUSEMOVE and WM_INPUT limited to the screen resolution?

If so, what is the benefit of using WM_INPUT?

Answer 1

RAWMOUSE gives you logical coordinates for the mouse based on the mouse's native resolution.

That is, you see the actual movement of the mouse.

Windows will use the mouse speed and acceleration (ballistics) settings to update the cursor position. Because of course the two are not linked - the apparent movement of the mouse must be interpreted to generate a cursor movement else how can more than one mouse be supported?

If you wish to control a pointer, as far as I can tell there is no reason to duplicate the Windows mouse ballistics calculations. Just let windows do it. Therefore for controlling the pointer, you should just use WM_MOUSEMOVE. That is, unless you wish to disable the mouse acceleration settings in your application.

However, if you want to control the player's POV (point of view), or use the mouse to control an in-game object such as a spaceship flight yoke, then the RAWMOUSE data gives you the best possible access to the movement of the mouse, and you can implement your own algorithm to convert that into flight yoke/POV movement.

Answer 2

The main benefit and reason to use it is that that with rawInput you can use two mouses or more. Presently I write small game prototype which is designed to be played by two players with two mouses/mices - It is more complicated but It works and it is not bad because I do nod need to link external libs.