Police Quest IV – Open Season is an SCI2 game. As such, it had a radically different way of doing several things. It’s not too hard though to backport one of its elements, namely its translucent windows.

I’ve tweeted about this at length, and actually had to reimplement it all over again. But I did it.

(class TranslucentWindow of SysWindow
  (method (open &tmp oldPort screens scaleX scaleY)
    ; Your standard setup, KQ6 style...
    (= lsLeft (- left 1))
    (= lsRight (+ right 1))
    (= lsTop (- top 1))
    (= lsBottom (+ bottom 1))
 
    (= type 128)
    (= priority 15)
    (super open:)
 
    (= oldPort (GetPort))
    (SetPort 0)
    (= screens VISUAL)
    (if (!= priority -1) (= screens (| screens PRIORITY)))
 
    ; 128 is 100% of the source image size, which is 8x8.
    ; (128 / source) * target --> 16 * target.
    (= scaleX (* (- lsRight lsLeft) 16))
    (= scaleY (* (- lsBottom lsTop) 16))
    (DrawCel 923 1 0 lsLeft lsTop 15 scaleX scaleY)
 
    ; Draw the frame
    (Graph grDRAW_LINE lsTop lsLeft lsTop (- lsRight 1) 0 -1 -1)
    (Graph grDRAW_LINE (- lsBottom 1) lsLeft (- lsBottom 1) (- lsRight 1) 0 -1 -1)
    (Graph grDRAW_LINE lsTop lsLeft (- lsBottom 1) lsLeft 0 -1 -1)
    (Graph grDRAW_LINE lsTop (- lsRight 1) (- lsBottom 1) (- lsRight 1) 0 -1 -1)
 
    ; Show what we have wrought.
    (Graph grUPDATE_BOX (- lsTop 4) (- lsLeft 4) (+ lsBottom 4) (+ lsRight 4) 1)     
    (SetPort oldPort)
  )
)

You’ll also need to do something about DText, up in Interface.sc, or you’ll get ugly opaque text in a translucent window. I use my own extended interpreter so I get the drop shadow for free, but here’s the deal:

(class DText of DItem
  ; Rest of the class elided.
  (method (draw)
    ; We don't get to use hotspot rects anymore, sorry.
    (Display text dsFONT font dsCOORD nsTop nsLeft dsWIDTH (- nsRight nsLeft) dsCOLOR 7 dsBACKGROUND -1 dsALIGN mode)
  )
)

And yeah, the color’s pretty much fixed too — the DrawControl kernel call uses the current port’s colors, which would be the window’s. No such luck unless you significantly mess with things to not only add a color property to DText but also set it somehow while not actually invoking DText yourself so yeeeeaaah this might not be the window style for you.

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