; UpdateGamma Example
; -------------------

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

; Fade level for a classic screen fade: 1.0 is normal, 0.0 is black
fade#=1.0

; UpdateGamma's optional flag asks the driver to calibrate the ramp
calibrate=0

While Not KeyDown(1)

    Cls

    ; [ and ] fade the picture down and back up
    If KeyDown(26) And fade>0 Then fade=fade-0.01
    If KeyDown(27) And fade<1 Then fade=fade+0.01

    ; Space toggles the calibrate flag
    If KeyHit(57) Then calibrate=1-calibrate

    ; Build the faded ramp...
    For i=0 To 255
        level#=i*fade
        SetGamma i,i,i,level,level,level
    Next

    ; ...then hand it to the display. Without this call the table you
    ; built with SetGamma just sits in memory.
    UpdateGamma calibrate

    ; Colour bars drawn straight to the screen
    For x=0 To 255
        Color x,x/2,255-x
        Rect 60+x,140,1,60
    Next

    ; The same bars run through the ramp by hand, so you can see the
    ; fade this example is asking the driver for
    For x=0 To 255
        Color GammaRed(x),GammaGreen(x/2),GammaBlue(255-x)
        Rect 60+x,220,1,60
    Next

    Color 255,255,255

    Text 0,0,"[ / ] : fade out and in   Space: calibrate flag   Esc: exit"
    Text 0,20,"UpdateGamma "+calibrate+"   (fade level "+fade+")"

    Text 60,120,"Drawn normally"
    Text 60,200,"Through the ramp UpdateGamma was given"

    Text 0,420,"On the DirectX 12 backend UpdateGamma accepts the table but"
    Text 0,440,"does nothing with it, so the window does not really fade."
    Text 0,460,"The lower bars show the fade the ramp describes."

    Flip

Wend

End