Polling winmm.dll for joystick axis position

[Desrat]

Hi all, long time since I was around these parts but once again APMS has me pulled back in again.

I need some help if I may be so bold, regarding the use of the winmm.dll in system32 folder to get the current value of a joystick axis.

I specifically need help making sense of how to call the dll function correctly, the documentation for C++ is here http://msdn.microsoft.com/en-gb/libr...=vs.85%29.aspx

I basically need the current value of the Z axis on joystick 1.

As always all help is appreciated.

[Imagine Programming]

I have not tested this, but this should work. If you'll be polling for a position very often, I suggest you allocate an instance of the info structure once and simply modify it via the call.

local winmm = Library.Load("Winmm.dll");
if(not winmm)then
	error("Winmm.dll could not be loaded");
end

-- the info structure
JOYINFOEX = MemoryEx.DefineStruct{
	UDWORD "dwSize";
	UDWORD "dwFlags";
	UDWORD "dwXpos";
	UDWORD "dwYpos";
	UDWORD "dwZpos";
	UDWORD "dwRpos";
	UDWORD "dwUpos";
	UDWORD "dwVpos";
	UDWORD "dwButtons";
	UDWORD "dwButtonNumber";
	UDWORD "dwPOV";
	UDWORD "dwReserved1";
	UDWORD "dwReserved2";
};

-- joyGetPosEx can return any of these values
JOYERR_NOERROR 			= 0x00000000;
MMSYSERR_NODRIVER 		= 0x00000006;
MMSYSERR_INVALPARAM 	= 0x0000000B;
MMSYSERR_BADDEVICEID	= 0x00000002;
JOYERR_UNPLUGGED		= 0x000000A7;
JOYERR_PARMS			= 0x000000A5;

-- simple wrapper for the call, returns a new buffer - don't forget to free it! 
JoyInfoEx = function(uJoyID) 
	local info = JOYINFOEX:New();
	if(info)then
		local result = winmm.JoyInfoEx(uJoyID, info:GetPointer());
		
		return result, info;
	end
end;

--[[ Usage: 
	local res, info = JoyInfoEx(7);
	if(info)then
		if(res == JOYERR_NOERROR)then
			Dialog.Message("test", tostring(info.dwXpos));
		end
		
		info:Free();
	end
]]

[Desrat]

Im sure you're on the right track there but the dialog outputs zero no matter which axis I attempt to poll.

[Shrek]

You are setting the correct identifier for the joystick in the function call?

[Desrat]

Yup tried 0-16 (I know there's 15 but wasn't sure if it was zero based)

[Desrat]

anyone with any further insight?

[Imagine Programming]

anyone with any further insight?

I unfortunately have no joystick :(

[webultra]

I used to load window's dlls with the alien module. I wrote a tested example of what you need. Hope it helps.

require "alien";

local tbl = {
    [0x00000000] = 'JOYERR_NOERROR',
    [0x00000006] = 'MMSYSERR_NODRIVER',
    [0x0000000B] = 'MMSYSERR_INVALPARAM',
    [0x00000002] = 'MMSYSERR_BADDEVICEID',
    [0x000000A7] = 'JOYERR_UNPLUGGED',
    [0x000000A5] = 'JOYERR_PARMS'
}

local winmm = alien.load("C:\\Windows\\System32\\winmm.dll");

local JOYINFOEX = alien.defstruct{
    {'dwSize', 'ulong'},
    {'dwFlags', 'ulong'},
    {'dwXpos', 'ulong'},
    {'dwYpos', 'ulong'},
    {'dwZpos', 'ulong'},
    {'dwRpos', 'ulong'},
    {'dwUpos', 'ulong'},
    {'dwVpos', 'ulong'},
    {'dwButtons', 'ulong'},
    {'dwButtonNumber', 'ulong'},
    {'dwPOV', 'ulong'},
    {'dwReserved1', 'ulong'},
    {'dwReserved2', 'ulong'}
}

winmm.joyGetPosEx:types{'uint', 'pointer', abi="stdcall", ret="uint"}
winmm.joyGetNumDevs:types{abi="stdcall", ret="uint"}

local joyGetNumDevs = winmm.joyGetNumDevs
local joyGetPosEx = winmm.joyGetPosEx;

local nDevs = joyGetNumDevs();
local joyEx = JOYINFOEX:new();

joyEx.dwSize = JOYINFOEX.size;
joyEx.dwFlags = 255; --JOY_RETURNALL
JOYSTICKID = -1;

for uJoyID = 0,nDevs-1 do
    local a =joyGetPosEx(uJoyID, joyEx());
    if (tbl[a] == 'JOYERR_NOERROR') then
        JOYSTICKID = uJoyID;
        print(JOYSTICKID, joyEx.dwZpos, joyEx.dwXpos, joyEx.dwYpos);
        break;
    end
end 

[Imagine Programming]

Based on your code with the Alien module, this should be the equivalent with MemoryEx:

local winmm = Library.Load("Winmm.dll");
if(not winmm)then
	error("Winmm.dll could not be loaded");
end

-- the info structure
JOYINFOEX = MemoryEx.DefineStruct{
	UDWORD "dwSize";
	UDWORD "dwFlags";
	UDWORD "dwXpos";
	UDWORD "dwYpos";
	UDWORD "dwZpos";
	UDWORD "dwRpos";
	UDWORD "dwUpos";
	UDWORD "dwVpos";
	UDWORD "dwButtons";
	UDWORD "dwButtonNumber";
	UDWORD "dwPOV";
	UDWORD "dwReserved1";
	UDWORD "dwReserved2";
};

-- joyGetPosEx can return any of these values
JOYERR_NOERROR 			= 0x00000000;
MMSYSERR_NODRIVER 		= 0x00000006;
MMSYSERR_INVALPARAM 	= 0x0000000B;
MMSYSERR_BADDEVICEID	= 0x00000002;
JOYERR_UNPLUGGED		= 0x000000A7;
JOYERR_PARMS			= 0x000000A5;

-- simple wrapper for the call, returns a new buffer - don't forget to free it! 
JoyInfoEx = function(uJoyID) 
	local info = JOYINFOEX:New();
	if(info)then
		info.dwSize  = MemoryEx.StructSize(JOYINFOEX);
		info.dwFlags = 255;
		local result = winmm.JoyInfoEx(uJoyID, info:GetPointer());
		
		return result, info;
	end
end;

--[[ Usage: 
	local res, info = JoyInfoEx(7);
	if(info)then
		if(res == JOYERR_NOERROR)then
			Dialog.Message("test", tostring(info.dwXpos));
		end
		
		info:Free();
	end
]]

[Desrat]

Based on your code with the Alien module, this should be the equivalent with MemoryEx:

Small error fixed below - thanks to both Imagine Programming and webultra for getting me the outcome I needed.

-- Original

local result = winmm.JoyInfoEx(uJoyID, info:GetPointer());

-- Corrected

local result = winmm.joyGetPosEx(uJoyID, info:GetPointer());

[Imagine Programming]

Small error fixed below - thanks to both Imagine Programming and webultra for getting me the outcome I needed.

Ah of course, that's a logical fix! So I assume you have it working now? :yes

[Desrat]

So I assume you have it working now? :yes

Yep, working great, however would you be able to explain what this entails though, as I do intend to call the function repeatedly.

I suggest you allocate an instance of the info structure once and simply modify it via the call.

[Shrek]

A structure is really just a table and when you call the function it updates the table with new information that you can then use, simple as that really.

If your doing this repetitively then change the function so that JOYINFOEX:New() is called just once on Global and info.dwSize with info.dwFlags are set just once as well as you don't need to keep creating a new structure object as you can just update the existing one and that will speed things up.

[Shrek]

Something like this:

-- Global

winmm = Library.Load("Winmm.dll");

JOYINFOEX = MemoryEx.DefineStruct{
	UDWORD "dwSize";
	UDWORD "dwFlags";
	UDWORD "dwXpos";
	UDWORD "dwYpos";
	UDWORD "dwZpos";
	UDWORD "dwRpos";
	UDWORD "dwUpos";
	UDWORD "dwVpos";
	UDWORD "dwButtons";
	UDWORD "dwButtonNumber";
	UDWORD "dwPOV";
	UDWORD "dwReserved1";
	UDWORD "dwReserved2";
};

JOYERR_NOERROR        = 0x00000000;
MMSYSERR_NODRIVER     = 0x00000006;
MMSYSERR_INVALPARAM   = 0x0000000B;
MMSYSERR_BADDEVICEID  = 0x00000002;
JOYERR_UNPLUGGED      = 0x000000A7;
JOYERR_PARMS          = 0x000000A5;

Jinfo = JOYINFOEX:New();
Jinfo.dwSize  = JOYINFOEX:Size();
Jinfo.dwFlags = 255;

JoyInfoEx = function(uJoyID)
  return winmm.JoyInfoEx(uJoyID, Jinfo:GetPointer());
end;

--[[ Usage:
	local res = JoyInfoEx(7);
	if(res == JOYERR_NOERROR)then
	 Dialog.Message("test", tostring(Jinfo.dwXpos));
	end
]]

[Desrat]

ok cool, I get the idea - cheers