var x, y : int := 0
var key : array char of boolean
var plane : int
plane := Pic.FileNew ("X-Wing1.bmp")
var back := Pic.FileNew ("space.jpg")
x := maxx div 2
y := maxy div 2
setscreen ("graphics:max;max")

View.Set ("offscreenonly, nocursor")



% delay for background

setscreen ("graphics:max,max,offscreenonly")
proc myDelay (var last : int, rate : int)
    var now : int
    loop
        clock (now)
        exit when now - last >= rate
    end loop
    last := now
end myDelay


% background

proc background (var y : int)
    y := y - 6
    if y < maxy - 1178 then
        y := 0
    end if

    Pic.Draw (back, 0, y, picCopy)
end background
var gunReady : boolean := true      % because processes can not take call be reference
% parameters this need to be global

type shotType :                     % Note how the use of records makes it easy to organize my code
    record
        x, y : real
        vx, vy : real %velocity of x, y
        live : boolean
    end record


process coolGun
    delay (200)
    gunReady := true
end coolGun

proc vectorToXY (mag, ang : real, var x, y : real)

    x := cosd (ang) * mag
    y := sind (ang) * mag
end vectorToXY

proc xyToVector (x, y : real, var mag, ang : real)

    mag := sqrt (x ** 2 + y ** 2)
    if mag > 0 then
        if x >= 0 then
            ang := arcsind (y / mag)
        else
            ang := 180 - arcsind (y / mag)
        end if
    else
        ang := 0
    end if
end xyToVector

proc trackInput (var mag, ang : real, var shotFired : boolean)
    shotFired := false
    var chars : array char of boolean
    Input.KeyDown (chars)
    if chars (' ') then    %Fire a shot
        shotFired := true
    end if
end trackInput

proc addShot (var shots : array 1 .. 10 of shotType)
    var mx, my, mb : int
    if gunReady then
        for i : 1 .. 10
            if not shots (i).live then
                gunReady := false
                fork coolGun            % this will set gunReady back to true in 150 mill
                shots (i).live := true
                shots (i).x := x - 7    %   This is so the shots come out of the ship
                shots (i).y := y + 9
                exit       % this is so that the shot only takes up one slot
            end if
        end for
    end if
end addShot

proc trackShots (var shots : array 1 .. 10 of shotType)
    for i : 1 .. 10
        if shots (i).live then
            if shots (i).y > maxy then
                shots (i).live := false     % so we can recycle the shots
            else
                shots (i).y += 5
            end if
        end if
    end for
end trackShots


proc drawScene (mag, ang : real, shots : array 1 .. 10 of shotType)
    var linex, liney : real
    var dx, dy : real

    vectorToXY (mag, ang, dx, dy)
    vectorToXY (25, ang, linex, liney)
    for i : 1 .. 10
        if shots (i).live then
            drawfilloval (round (shots (i).x + 28), round (shots (i).y - 5), 1, 10, brightblue)
            drawfilloval (round (shots (i).x - 24), round (shots (i).y - 5), 1, 10, brightblue)
        end if
    end for

end drawScene

var shots : array 1 .. 10 of shotType       % All the data about the 10 shots that our
% gun can fire
for i : 1 .. 10
    shots (i).live := false                 % clear the shots array to allow for new shots
end for

% ----------------------------   MAINLINE   ------------------------------------

var backy, last := 0

loop
    Input.KeyDown (key)
    if key (KEY_UP_ARROW) then
        y := y + 4
    end if
    if key (KEY_DOWN_ARROW) then
        y := y - 4
    end if
    if key (KEY_RIGHT_ARROW) then
        x := x + 4
    end if
    if key (KEY_LEFT_ARROW) then
        x := x - 4
    end if
    x := max (35, x)
    y := max (35, y)
    x := min (maxx - 93, x)
    y := min (maxy - 10, y)

    background (backy)
    %   Draw the plane
    Pic.Draw (plane, x - 35, y - 35, picMerge)

    %  Controls
    myDelay (last, 20)
    View.Update
    var shotFired : boolean     % Did the user try to shoot (won't shoot if gun is "hot"
    var ang : real := 0     % current angle of the big gun
    var mag : real := 10    % Amount of power being used for the shots

 
    trackInput (mag, ang, shotFired)
    if shotFired then
        addShot (shots)
    end if
    trackShots (shots)
    drawScene (mag, ang, shots)
    View.Update
    delay (10)
end loop