setscreen ("offscreenonly")

var forePic, bgPic : int

forePic := Pic.FileNew ("pic1.bmp")
bgPic := Pic.FileNew ("pic2.bmp")

Pic.Draw (forePic, 0, 0, picCopy)

for i : 1 .. Pic.Width (forePic)
    for j : 1 .. Pic.Height (forePic)
    % These loops analyse each pixel in the foreground picture.

        if i mod 2 = 0 and j mod 2 = 0 then
        % Select every other pixel.  Change this line to change the
        % pattern.

        /*
         Around here you can add lines like
         "if whatdotcolour (i,j) = 0 then"
         So that you can decide whether or not to follow through with the next line.
         */
            drawdot (i, j, colourbg)
            % This clause draws the colourbg colour at alternating points,
            % but this colour itself is entirely transparent!
        end if
    end for
end for

forePic := Pic.New (0, 0, Pic.Width (forePic), Pic.Height (forePic))
% Creates the resultant pic.

Pic.Draw (bgPic, 0, 0, picCopy)
Pic.Draw (forePic, 20, 20, picMerge)
% Merge the pictures together.

%Pic.Draw (forePic, 20, 20, picXor)
% For a spooooky effect.

View.Update