Loop or Timer?

In C++, I know you use a main game loop to go through all the code constantly. But I want to know if Visual basic games usually use something like that or not, or if it all gets put on a real fast timer.

If it IS done with a loop, please tell me how.

Timers are Evil(tm)

VB Code:

Do
   'here goes your code
Loop until ExitCondition

Here's my rather messy main loop from my engine (slightly edited):

VB Code:

Dim cInc As Single
Dim PerfFrequency As Currency, PerfTime As Currency, RealFPS As Double
Dim StartTime As Currency, EndTime As Currency, m_strCaption As String
    Call QueryPerformanceFrequency(PerfFrequency)
    m_Engine.DesiredFramerate = 1000 \ (1000 \ ClipValue(m_Engine.DesiredFramerate, c_lngMinFramerate, c_lngMaxFramerate))
    m_Engine.Running = True
    Do While m_Engine.Running = True
        If m_booCritical Then
            DoEvents
        Else
            If QueryPerformanceCounter(PerfTime) = 0 Then
                CurrentTime = GetTickCount
                StartTime = CurrentTime
            Else
                CurrentTime = GetTickCount
                StartTime = Int((PerfTime / PerfFrequency) * 1000)
            End If
            If LastTime = 0 Then LastTime = CurrentTime
            FramesToRender = Abs(CurrentTime - LastTime) + FramerateBuildup
            FramerateBuildup = 0
            MSPerFrame = 1000 \ m_Engine.DesiredFramerate
            FramerateBuildup = FramesToRender Mod MSPerFrame
            If m_Engine.BalanceFramerate Then
                FramesToRender = FramesToRender \ MSPerFrame
            Else
                FramesToRender = 1
            End If
            If FramesToRender > c_lngMaxFrameskip Then FramesToRender = c_lngMaxFrameskip
            If FramesToRender > 0 Then
                If m_Engine.Paused Then
                    FramesToRender = 0
                Else
                    For RenderFrames = 1 To FramesToRender
                        If m_Engine.Paused Then Else m_Engine.Update
                        IncUPS = IncUPS + 1
                        If m_Engine.Running = False Then Exit For: Exit Do
                    Next RenderFrames
                End If
                If m_Engine.Running Then Redraw
                If m_GFX.Window.WindowState = 1 Then
                Else
                    If m_Engine.Running Then m_GFX.FlipImage m_Backbuffer
                End If
                IncFPS = IncFPS + 1
            Else
                If m_Engine.HarassCPU Then Else Call SleepEx(1, True)
            End If
            If m_Engine.Running = False Then Exit Do
            If QueryPerformanceCounter(PerfTime) = 0 Then
                EndTime = GetTickCount
            Else
                EndTime = Int((PerfTime / PerfFrequency) * 1000)
            End If
            If m_Engine.Running = False Then Exit Do
            If Int(CurrentTime \ 1000) <> Int(LastTime \ 1000) Then
                CurrentFPS = IncFPS
                CurrentUPS = IncUPS
                IncFPS = 0
                IncUPS = 0
            End If
            LastTime = CurrentTime
            DoEvents
        End If
    Loop
    Shutdown

It manages to maintain very very accurate framerates, with frameskipping, all without harassing the CPU (usually CPU usage stays between 0 and 10% when running at 60fps, unless the game is really detailed at the moment).

Hope this helps, if you want some help understanding it, let me know - it's not commented :P

Wheres the loop go? In its own sub? If so, where does THAT sub get put?

well you can make a sub like this
sub MainLoop()
end sub

just place it anywhere you want
now if you want to call it you could have a button for example or just put it into the form load event

My loop is called when I press a command button. But after I do, it freezes up. This is the code for my loop:

Sub Run()

Do
If GetKeyState(vbKeyA) = 1 Then
MsgBox "Key A pressed"
End If
If GetKeyState(vbKeyQ) = 1 Then
Running = False
End If
Loop Until Running = False

End Sub

well this should work but maybe you should add a
DoEvents into the loop

and format your code...

I got my loop to stop crashing, but something might be wrong with my GetKeyState thing.

Sub CheckMove()
If GetKeyState(vbKeyUp) = 1 Then
PC.xvel = PC.xpos - PC.xview
PC.yvel = PC.ypos - PC.yview
PC.xpos = PC.xpos + PC.xvel
PC.ypos = PC.ypos + PC.yvel
frmGame.Caption = PC.xpos
End If

End Sub

I put CheckMove in my loop, and then in one press it overflows. I have in a different sub setting xpos and ypos to 0, and xview and yview to 120.

use gettickcount to check when the key was last pressed, and only allow another press after about 10ms or some value that you like... otherwise it can be really fast!

How do I use it, and where do I use it?

VB Code:

Sub CheckMove() 
static LastPress as long
  if lastpress<Gettickcount then
    lastpress = gettickcount +50 'this will allow a keydown all 50 milli seconds
    if GetKeyState(vbKeyUp) = 1 Then 
      PC.xvel = PC.xpos - PC.xview 
      PC.yvel = PC.ypos - PC.yview 
      PC.xpos = PC.xpos + PC.xvel 
      PC.ypos = PC.ypos + PC.yvel 
      frmGame.Caption = PC.xpos 
    end if
  End If 
End Sub

Now it doesn't do anything... do I have to do anything else anywhere?

You have to call from inside a loop..

VB Code:

While DoEvents
       CheckMove
   Wend

I've already done that, otherwise it would never have worked, therefore preventing the overflow:)