setscreen ("graphics:max;max")
var mx, my, mb : int

proc shade (x1, y1, x2, y2 : int, col : int)
    for decreasing j : y2 .. y1 by 3
        for i : x1 .. x2 by 3
            Draw.Dot (i, j, col)
        end for
    end for
    for decreasing j : y2 - 1 .. y1 by 3
        for i : x1 + 1 .. x2 - 1 by 3
            Draw.Dot (i, j, col)
        end for
    end for
end shade

var temp := 1
var x1, y1, x2, y2 : int := 0
var chars : array char of boolean

Pic.ScreenLoad ("C:/water.jpg", 100, 100, picUnderMerge)%add a picture to see a bit how it works
loop
    Mouse.Where (mx, my, mb)

    Input.KeyDown (chars)
    if chars ('t') then
        put "The T key is pressed"
    end if
    if mb = 1 and temp = 1 then
        x1 := mx
        y1 := my
        temp := 0
    elsif mb = 1 and temp = 0 then
        x2 := mx
        y2 := my
        shade (x1, y1, x2, y2, 15)
    elsif mb = 0 then
        temp := 1
    end if

end loop

proc shade (x1, y1, x2, y2 : int, col : int)
    for i : min (x1, x2) .. max (x1, x2) by 3
        for j : min (y1, y2) .. max (y1, y2) by 3
            Draw.Dot (i, j, col)
        end for
    end for
    % etc
end shade

proc shade (x1, y1, x2, y2 : int, col : int)
    for i : min (x1, x2) .. max (x1, x2)
        for j : min (y1, y2) .. max (y1, y2)
            var Colour : int
            var r, g, b : real
            var Colour2 : int
            Colour := whatdotcolour (i, j)
            RGB.GetColour (Colour, r, g, b)
            Colour2 := RGB.AddColour (r / 2, g / 2, b / 2)
            Draw.Dot (i, j, Colour2)
        end for
    end for
end shade