VB:Tutorials:WINAPI:Joystick Input
From GDWiki
Tutorial by Nicholas Gorski (GMan)
This tutorial will use the Windows API to get joystick input.
Contents |
[edit] API Definitions
Here is a list of what functions and type's we will need. I suggest adding a module or class to your project and adding these there.
[edit] Function's
Public Declare Function joyGetPosEx Lib "winmm.dll" (ByVal uJoyID As Long, _ pji As JOYINFOEX) As Long Public Declare Function joyGetDevCapsA Lib "winmm.dll" (ByVal uJoyID As Long, _ pjc As JOYCAPS, ByVal cjc As Long) As Long
joyGetPosEx returns input information.
joyGetDevCapsA returns information on the joystick.
[edit] Type's
Public Type JOYCAPS wMid As Integer wPid As Integer szPname As String * 32 wXmin As Long wXmax As Long wYmin As Long wYmax As Long wZmin As Long wZmax As Long wNumButtons As Long wPeriodMin As Long wPeriodMax As Long wRmin As Long wRmax As Long wUmin As Long wUmax As Long wVmin As Long wVmax As Long wCaps As Long wMaxAxes As Long wNumAxes As Long wMaxButtons As Long szRegKey As String * 32 szOEMVxD As String * 260 End Type Public Type JOYINFOEX dwSize As Long dwFlags As Long dwXpos As Long dwYpos As Long dwZpos As Long dwRpos As Long dwUpos As Long dwVpos As Long dwButtons As Long dwButtonNumber As Long dwPOV As Long dwReserved1 As Long dwReserved2 As Long End Type
[edit] Other public variables
Public JoyNum As Long Public MYJOYEX As JOYINFOEX Public MYJOYCAPS As JOYCAPS Public CenterX As Long Public CenterY As Long Public JoyButtons(15) as Boolean Public CurrentJoyX As Long Public CurrentJoyY As Long
[edit] Coding the Input
Create a function named StartJoystick. All this does is get the CAPS and Center positions:
Public Function StartJoystick(Optional ByVal JoystickNumber As Long = 0) As Boolean JoyNum = JoystickNumber If joyGetDevCapsA(JoyNum, MYJOYCAPS, 404) <> 0 Then 'Get joystick info StartJoystick = False Else Call joyGetPosEx(JoyNum, MYJOYEX) CenterX = MYJOYEX.dwXpos CenterY = MYJOYEX.dwYpos StartJoystick = True End If End Function
As you can see, it's not too complicated. The JoystickNumber variable is what joystick you want to get input from. This is usually zero, but can be one [or two for hardcore users...:)].
Next, add a function called PollJoystick. This function will get all the information from the joystick, then sort it out:
Public Sub PollJoystick() Dim i As Long Dim t As Long MYJOYEX.dwSize = 64 MYJOYEX.dwFlags = 255 ' Get the joystick information Call joyGetPosEx(JoyNum, MYJOYEX) t = MYJOYEX.dwButtons For i = 15 To 0 Step -1 JoyButtons(i) = False If (2 ^ i) <= t Then t = t - (2 ^ i) JoyButtons(i) = True End If Next i CurrentJoyX = MYJOYEX.dwXpos CurrentJoyY = MYJOYEX.dwYpos End Sub
Now you have the ability to get input from the joystick. But how do you use it? And what's with the complicated code? Well, that complicated code is what tells you what buttons are pressed. How? When you press button zero on your joystick, the joystick tells the computer 1. Press one, it says 2. But press two, it says four. Press three, and its 8. See the pattern? If not, here it is:
2^0=1 2^1=2 2^2=4 2^3=8 2^4=16 2^5=32
See? So press buttons zero, two and three, and the joystick tells the computer 11. How do we sort this out? Start with the highest number, then goto zero. If the current number is within the input number (11 in our example), then subtract that from from the number. So in our example, it would get the 2^3=8, so subtract it, leaving us with 3. Then it gets to 2^1=2, subtract it, leaving 1. So then 2^0=1, subtract it, leaving zero. Get it? If not, trust me (I'm bad at explaining algorithms).
[edit] Done
Download the source code to see it in action, in a stupid little game.
Files:VB6_WindowsApi_Joystick.zip
