; VWait Example
; -------------

Graphics 640,480,0,2
SetBuffer BackBuffer()

; VWait makes the CPU wait for the monitor's next vertical blank, so
; the loop runs once per screen refresh. It is often paired with
; "Flip False": VWait does the waiting, then Flip False shows the
; frame immediately without waiting again.

use_vwait=1

While Not KeyDown(1)

    Cls

    ; Space toggles VWait on and off
    If KeyHit(57) Then use_vwait=1-use_vwait

    ; One step per loop: without VWait the loop is unthrottled
    ; and the square streaks across the screen
    x=(x+4) Mod 640
    Rect x,220,40,40,True

    Text 0,0,"Space: toggle VWait   Esc: exit"
    If use_vwait Then
        Text 0,20,"VWait ON: one loop per screen refresh"
    Else
        Text 0,20,"VWait OFF: loop runs unthrottled"
    EndIf

    ; The documented command: wait for the vertical blank
    If use_vwait Then VWait

    Flip False

Wend

End