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In the spirit of Terry's Tutorials - GUARDIAN Alien Space Ship Game
#18
Added ASCII city below where alien abductions are -500 points per incident and a "High Score" board if you win and have a top 5 score.

GUARDIAN V 1.3
Code: (Select All)
DEFINT H-K
$RESIZE:ON
$COLOR:32
_RESIZE OFF
RANDOMIZE TIMER
' Note: timer is not adjusted for stroke of midnight event, so don't stay up late playing this.
REM Main
f1 = 22 ' Sets font size to 22 and calculates the max screen height and width for your desktop.
h = (_DESKTOPHEIGHT - 60) \ f1
w = _DESKTOPWIDTH \ (f1 / 1.66)
WIDTH w, h
_SCREENMOVE 0, 0
fontpath$ = ENVIRON$("SYSTEMROOT") + "\fonts\lucon.ttf" 'Find Windows Folder Path.
font& = _LOADFONT(fontpath$, f1, "monospace")
_FONT font&
_DELAY .25
_RESIZE ON , _SMOOTH ' Allows resizing. Note: this is for slight adjustments. As of this version there is no compensatory function to change the font size during screen size changes.

TYPE gen_var
    intro AS INTEGER ' Runs a protion of the alien subroutine as part of the intro.
    nol AS INTEGER ' Number of game levels.
    redo_level AS INTEGER ' Alien abdution results in redo level.
    level AS INTEGER ' Current game level.
    level_up AS INTEGER ' Routes code to next game level.
    top AS INTEGER ' Top boundary. (Changeable).
    bottom AS INTEGER ' Bottom boundary. (Changeable).
    left AS INTEGER ' Left boundary. (Changeable).
    right AS INTEGER ' Right boundary. (Changeable).
    kb_access AS INTEGER ' Routes code to either Guardian/Alien or general keyboard routine. -1 Guardian/Alien, 0 keyboard.
    mouse_or_key_move AS INTEGER
    mouse_get_screen AS INTEGER
    play AS INTEGER
    snd1 AS LONG ' Explosion sound effect.
    snd2 AS LONG ' Explosion sound effect.
END TYPE

DIM SHARED v AS gen_var

TYPE guardian
    difficulty AS INTEGER
    population AS _INTEGER64
    num AS INTEGER ' Number of Guardians aka lives.
    diry AS INTEGER ' Guardian row move. +1, 0, -1.
    dirx AS INTEGER ' Guardian column move. +2, 0, -2. Equals vertical pixel movement. 16x8.
    y AS INTEGER ' Guardian coordinates row.
    x AS INTEGER ' Guardian coordinates column.
    thrusters AS INTEGER ' Guardian speed. (User Determined).
    m_max AS INTEGER ' Restricts # of missiles fired in one direction.
    m_status AS INTEGER ' Missile status. -1 when fired, 1 while moving.
    m_fired AS INTEGER ' The number of missile deployed and still active.
    m_n AS INTEGER ' FOR/NEXT counter variable shared by other routines to index through the number of missiles fired in a specific direction.
    m_d AS INTEGER ' Missile direction. (1-8).
    m_y AS INTEGER ' Missile row advancement increment: +1, 0, -1 Note: Missile row and column coordinates are defined in arrays.
    m_x AS INTEGER ' Missile column advancement increment: +2, 0, -2. Equals vertical pixel movement. 16x8.
    m_asc AS INTEGER ' ASCII character representing a fired missile.
    m_launcher AS STRING
    icon AS STRING ' Guardian comm icon. For this edition, it is the same as the flagship: "*"
    flagship AS STRING ' Guardian ascii character.
END TYPE

DIM SHARED g AS guardian

TYPE alien
    max AS INTEGER ' Maximum # of alien ships on screen.
    count AS INTEGER ' Number of alien ships. (Counter).
    itr AS INTEGER ' Iteration array number to cycle through the active alien ships. (Counter).
    cycle_delay AS SINGLE ' Timer cycle controls how fast alien ships move.
    ai AS INTEGER ' Degree of artificial intelligence. (0-2)
    ship AS STRING ' Alien ship ASCII design.
END TYPE

DIM SHARED a AS alien
DIM SHARED Overlay

DO
    GOSUB set_arrays

    SELECT CASE v.play
        CASE 0
            CALL set_up
            CALL city
            v.level = 1
            CALL comm
            CALL intro
            v.level = 0: g.population = 100000 ' Reset from intro demo.
            GOSUB set_arrays: GOSUB zero_variables ' Reset arrays and zero variables after intro.
            CALL level_up
            CALL comm
        CASE 1
            CALL set_up
            CALL city
            CALL comm
    END SELECT

    CALL game_level ' Display level.

    g.y = (v.bottom - v.top) \ 2 + v.top: g.x = (v.right - v.left + 1) \ 2 + v.left ' Set initial column and row for Guardian craft.

    CALL game

    IF g.num = 0 OR v.level = v.nol AND v.redo_level = 0 THEN
        CALL game_over ' Determines win or lose.
        v.level = 1 ' Reinitiate if player chooses to replay.
    ELSE
        IF v.redo_level = 0 THEN CALL level_up
    END IF

    GOSUB zero_variables
LOOP

set_arrays:
ii = 15 ' Default max setting for number of alien ships used here to initially dim arrays.
g.m_max = 8 ' * missiles max per direction.
REDIM SHARED a_y(ii), a_x(ii), a_mask_y(ii), a_mask_x(ii), a_inertia(ii) ' Alien movement.
REDIM SHARED a_ran(ii), a_olda_ran(ii), a_y_loc(ii), a_x_loc(ii), a_offscrn(ii) ' Alien movement.
REDIM SHARED m_n(8), m_x(g.m_max, 8), m_y(g.m_max, 8) ' Guardian missiles. 8 represents 8 possible diretions of movement and missile fire.

' Array descriptions and actions.
' a_y() , a_x() Alien ship positions rows and columns.
' a_mask_y(), a_mask_x() Alien ship last position. Masked on next move.
' a_inertia(ii) Number of moves in one direction selected by random for an alien ship.
' a_ran(ii), a_olda_ran(ii) Determines the direction in which the inertia will travel and the prior direction is kept to disallow the same direction twice.
' a_y_loc(ii), a_x_loc(ii) The row and column coordinates of the aliens ships.
' m_n(8), m_x(g.m_max, 8), m_y(g.m_max, 8)  Missile number and Missile index 1 to g.m_max for position. 8 is the fixed number of 8 different directions.
RETURN

zero_variables:
' Zero variables.
g.diry = 0: g.dirx = 0: g.m_status = 0: g.m_fired = 0: g.m_d = 0: g.m_y = 0: g.m_x = 0: v.redo_level = 0: a.max = 0: v.intro = 0
a.count = 0: a.itr = 0: a.cycle_delay = 0: v.level_up = 0: v.mouse_or_key_move = 0: g.m_launcher = ""
RETURN

skipintro: ' ONKEY 15.
v.intro = 999
KEY(15) OFF
RETURN

' Error handler.
offscreen: ' Prevents error if blast particles row and column are off-screen. Effect is a partial blast on side of screen.
IF ERR = 5 THEN er = -1: RESUME NEXT
PRINT "Opps, unexpected error"; ERR
END

SUB intro
    WHILE -1 ' Faux loop.
        v.mouse_get_screen = 1 ' Allows skip intro by mouse selection.
        LOCATE _HEIGHT - 1, _WIDTH - 15
        COLOR 8: PRINT "[S]kip Intro";: COLOR 7 ' Option to skip the intro using the "S" key with ONKEY statement.
        KEY 15, CHR$(0) + CHR$(31) 'scancode for S
        ON KEY(15) GOSUB skipintro
        KEY(15) ON 'turn ON [S]kip intro event trapping.
        j = (v.bottom - v.top) \ 2 + v.top
        k = (v.right - v.left) \ 2 + v.left
        z1 = TIMER
        DO
            CALL mouse(0, 0)
            IF v.intro = 999 THEN CALL skip_intro: EXIT WHILE
        LOOP UNTIL ABS(z1 - TIMER) > .33
        SOUND 1000, .3
        msg$ = " GUARDIAN "
        LOCATE j, k - LEN(msg$) \ 2: COLOR 14: PRINT msg$;: COLOR 7
        LOCATE , k
        z1 = TIMER
        DO
            CALL mouse(0, 0)
            IF v.intro = 999 THEN CALL skip_intro: EXIT WHILE
        LOOP UNTIL ABS(z1 - TIMER) > .66
        msg$ = SPACE$(LEN(msg$))
        LOCATE j, k - LEN(msg$) \ 2: COLOR 7: PRINT msg$;
        LOCATE j, k
        IF v.intro = 999 THEN CALL skip_intro: EXIT WHILE ELSE CALL explosion
        LOCATE j, k: COLOR 15 + 16: PRINT g.flagship;
        z1 = TIMER
        DO
            CALL mouse(0, 0)
            IF v.intro = 999 THEN CALL skip_intro: EXIT WHILE
        LOOP UNTIL ABS(z1 - TIMER) > .75
        v.intro = -1: a.max = 10
        FOR i = 1 TO 90
            CALL mouse(0, 0)
            IF v.intro = 999 THEN CALL skip_intro: EXIT WHILE
            SOUND 900, .05
            CALL alien_move
            LOCATE j, k: COLOR 15: PRINT g.flagship;: COLOR 7
            _DELAY .07
        NEXT
        z1 = TIMER
        DO
            CALL mouse(0, 0)
            IF v.intro = 999 THEN CALL skip_intro: EXIT WHILE
        LOOP UNTIL ABS(z1 - TIMER) > 1
        LOCATE j, k: PRINT " ";
        CALL guardian_abduction
        a.max = 0
        z1 = TIMER
        DO
            CALL mouse(0, 0)
            IF v.intro = 999 THEN CALL skip_intro: EXIT WHILE
        LOOP UNTIL ABS(z1 - TIMER) > .5
        EXIT WHILE
    WEND
    LOCATE v.bottom, _WIDTH - 20: PRINT SPACE$(20);

    ' Playing Instructions.
    REDIM msg$(13)
    msg$(1) = CHR$(249) + " " + "Look towards the top of your screen for Guardian ship status."
    msg$(2) = CHR$(249) + " " + "Hold arrow keys up/dn/lt/rt or in combination to move diagonally."
    msg$(3) = CHR$(249) + " " + "Missiles can be fired simultaneously in 8 different directions."
    msg$(4) = CHR$(249) + " " + "Press Tab to fire 1-8 missiles in the direction of movement."
    msg$(5) = CHR$(249) + " " + "Press Rt Ctrl to increase thrust, or Rt Alt to reduce thrust."
    msg$(6) = ""
    msg$(7) = CHR$(249) + " " + "Mouse alternative: "
    msg$(8) = CHR$(249) + " " + "Hold right mouse button to move toward mouse pointer."
    msg$(9) = CHR$(249) + " " + "Click left mouse button to fire 1-8 missiles in direction of mouse pointer."
    msg$(10) = CHR$(249) + " " + "Mouse wheel up for more thrust, wheel down for less."
    msg$(11) = CHR$(249) + " " + "Note: Tab and left mouse button cannot be used simultaneously."
    msg$(12) = ""
    msg$(13) = CHR$(249) + " " + "If you come in contact with an alien ship, your ship and crew get abducted."
    j = 0
    FOR i = 1 TO UBOUND(msg$)
        IF LEN(msg$(i)) > j THEN j = LEN(msg$(i))
    NEXT
    i = ((v.right - v.left) - j) \ 2
    t_mrgn = 6: b_mrgn = _HEIGHT - 4: l_mrgn = i + 1: r_mrgn = v.right - i
    LOCATE t_mrgn - 2, l_mrgn - 2: PRINT STRING$(r_mrgn - l_mrgn + 4, CHR$(196));
    LOCATE b_mrgn + 2, l_mrgn - 2: PRINT STRING$(r_mrgn - l_mrgn + 4, CHR$(196));
    FOR i = 1 TO b_mrgn - t_mrgn + 3
        LOCATE t_mrgn - 2 + i, l_mrgn - 2
        PRINT CHR$(179);
        LOCATE , r_mrgn + 2: PRINT CHR$(179);
    NEXT
    LOCATE t_mrgn - 2, l_mrgn - 2: PRINT CHR$(218);
    LOCATE t_mrgn - 2, r_mrgn + 2: PRINT CHR$(191);
    LOCATE b_mrgn + 2, l_mrgn - 2: PRINT CHR$(192);
    LOCATE b_mrgn + 2, r_mrgn + 2: PRINT CHR$(217);
    msg$ = "<Intro>"
    LOCATE t_mrgn - 2, l_mrgn + (r_mrgn - l_mrgn) \ 2 - LEN(msg$) \ 2
    PRINT msg$;
    msg$ = "You are the Captain of the Guardian, an elite battle cruiser commissioned to protect our planet against alien invaders. You have 3 lives. Every time you are abducted by an alien ship, you lose a life. If you survive, and wipe out all 3 flights of alien attacks, your mission is completed. You saved Earth!"
    j = r_mrgn - l_mrgn
    LOCATE t_mrgn, l_mrgn
    msg$ = RTRIM$(msg$) + " " ' Simple word parser routine.--------
    DO
        x$ = MID$(msg$, 1, j)
        x$ = MID$(x$, 1, _INSTRREV(x$, " ") - 1)
        msg$ = LTRIM$(MID$(msg$, LEN(x$) + 1))
        LOCATE , l_mrgn: PRINT x$
    LOOP UNTIL msg$ = "" '-----------------------------------------
    PRINT
    FOR i = 1 TO UBOUND(msg$)
        LOCATE , l_mrgn
        IF LEN(msg$(i)) THEN PRINT msg$(i) ELSE PRINT
    NEXT
    PRINT: IF CSRLIN < b_mrgn - 1 THEN PRINT
    msg$ = "Select Player Level: [1] Beginner  [2] Intermediate  [3] Advanced"
    LOCATE , l_mrgn + (r_mrgn - l_mrgn) \ 2 - LEN(msg$) \ 2
    PRINT msg$;
    DO
        _LIMIT 10
        CALL mouse(0, 0)
        ky$ = INKEY$
        IF LEN(ky$) OR g.difficulty THEN
            IF ky$ = CHR$(27) THEN SYSTEM
            SELECT CASE ky$
                CASE "1": g.difficulty = 1
                CASE "2": g.difficulty = 2
                CASE "3": g.difficulty = 3
            END SELECT
            IF g.difficulty THEN EXIT DO
        END IF
    LOOP
    VIEW PRINT v.top TO v.bottom: CLS 2: VIEW PRINT
END SUB

SUB skip_intro
    KEY(15) OFF
    v.intro = 0
    BEEP: _DELAY .3: BEEP
    VIEW PRINT v.top TO v.bottom
    COLOR 7
    CLS 2
    VIEW PRINT
    _DELAY .5
END SUB

SUB set_up
    v.top = 3: v.bottom = _HEIGHT - 1: v.left = 1: v.right = _WIDTH ' Boundaries.
    LOCATE v.top - 1, 1: PRINT STRING$(_WIDTH, CHR$(196));
    v.nol = 3
    g.population = 100000
    g.flagship = CHR$(15)
    a.ship = "-<>-"
    g.num = 3 ' 3 Guardian (lives) to start.
    g.thrusters = 10 ' Shows 1/2 thrust at start up on comm.
    g.icon = g.flagship
    g.m_asc = 250: g.diry = -1: ' Initiate missile ASCII character. g.diry = -1 initiates fire upwards if unmoved.
    IF _FILEEXISTS("Thunder1.ogg") AND _FILEEXISTS("Thunder1.ogg") AND _FILEEXISTS("Thunder1.ogg") AND _FILEEXISTS("Thunder1.ogg") THEN ' Sound effects provided by TheBOB, Bob Seguin, from The QBasic Forum.
        v.snd1 = _SNDOPEN("Thunder1.ogg", "SYNC")
        v.snd2 = _SNDOPEN("Thunder7.ogg", "SYNC")
    END IF
    v.play = -1 ' Skip into on replay.
END SUB

SUB game
    STATIC mouse_event1, mouse_event2
    REM Set mouse_event2 = 0 here to produce constant motion with directional changes.
    'Press single or arrow key combo to move. Rt Ctrl = faster / Rt Alt = slower. Tab to fire missles.
    g.thrusters = 10 ' Guardian movement delay. (1 to 20). Rt Ctrl = faster / Rt Alt = slower.

    SELECT CASE v.level
        CASE 1: a.max = 5 ' Sets number of space ships and initiates attack.
        CASE 2: a.max = 10
        CASE 3: a.max = 15
    END SELECT

    a.count = a.max
    IF a.max < 6 THEN
        SELECT CASE g.difficulty
            CASE 1: a.cycle_delay = .15: a.ai = 0
            CASE 2: a.cycle_delay = .05: a.ai = 1
            CASE 3: a.cycle_delay = 0: a.ai = 2
        END SELECT
    ELSEIF a.max < 11 THEN
        SELECT CASE g.difficulty
            CASE 1: a.cycle_delay = .125: a.ai = 0
            CASE 2: a.cycle_delay = .05: a.ai = 1
            CASE 3: a.cycle_delay = .003: a.ai = 2
        END SELECT
    ELSE
        SELECT CASE g.difficulty
            CASE 1: a.cycle_delay = .1: a.ai = 0
            CASE 2: a.cycle_delay = .03: a.ai = 1
            CASE 3: a.cycle_delay = .001: a.ai = 2
        END SELECT
    END IF

    _KEYCLEAR ' Clear any previous key presses in buffer.
    CALL mouse(0, 0) ' Clear mouse.

    DO
        _LIMIT 60 ' Display at 60 frames per second.

        CALL comm

        IF g.m_status THEN CALL Guardian_missiles ' g.m_status determines Guardian or alien turn. 1 = Guardian, -1 = alien.

        IF a.count = 0 THEN EXIT SUB ' Moving on to next level.

        CALL alien_move

        ' To change thrusters only when guardian moves, remove the timer and move this routine to: IF v.kb_access = -1 THEN
        IF ABS(z3 - TIMER) > .1 THEN ' z3 is a keypress delay timer for Guardian thrusters. Check every .1 seconds for a speed change.
            IF _KEYDOWN(100307) AND g.thrusters < 20 THEN g.thrusters = g.thrusters + 1 ' Rt Ctrl key. Slows down Guardian ship down.
            IF _KEYDOWN(100305) AND g.thrusters > 0 THEN g.thrusters = g.thrusters - 1 '  Rt Alt key. Speeds up Guardian ship.
            z3 = TIMER
        END IF

        IF ABS(z2 - TIMER) > g.thrusters / 100 THEN ' z2 is delay for Guardian movement cycle. Note: Division needed because computer math can't add decimal numbers correctly.
            IF v.kb_access = 0 THEN
                IF _KEYDOWN(18432) OR _KEYDOWN(19200) OR _KEYDOWN(19712) OR _KEYDOWN(20480) OR mouse_event2 = -1 THEN ' Arrow keys.
                    v.kb_access = -1 ' Routes code to guardian move. When zero, Guardian move gets bypassed.
                    z1 = TIMER ' Delay timer for key lag effect in Guardian move routine.
                END IF
            END IF
        END IF

        IF v.kb_access = -1 THEN ' Guardian move routine.-----------------------------------------------------------------------------------------------------------------------------
            IF ABS(z1 - TIMER) > .05 THEN ' z1 is a key lag time delay to allow guardian to press two keys together within a reasonable amount of time.
                DO ' Faux loop added to throw out illegal key combos like up + down.
                    IF mouse_event2 = 0 THEN ' Bypass this keyboard routine if the right mouse button is in use.
                        IF mouse_event1 = 0 THEN g.m_x = 0: g.m_y = 0 ' Variables to control length and direction of Guardian movement. Must be reset to zero each cycle so diagonal moves are possible.

                        IF g.m_x = 0 AND g.m_y = 0 THEN
                            ' Eliminate illegal combos.
                            IF _KEYDOWN(18432) AND _KEYDOWN(20480) THEN v.kb_access = 0: z2 = TIMER: EXIT DO ' Up + down
                            IF _KEYDOWN(19712) AND _KEYDOWN(19200) THEN v.kb_access = 0: z2 = TIMER: EXIT DO ' Left + right.

                            ' IF female THEN STOP AND GET #1, directions. Keys that control movement.
                            IF _KEYDOWN(18432) THEN ' Up-arrow.
                                g.m_y = -1 ' To move 1-row up.
                            END IF
                            IF _KEYDOWN(19712) THEN ' Right-arrow.
                                g.m_x = 1 ' To move 1-column right.
                            END IF
                            IF _KEYDOWN(20480) THEN ' Down-arrow.
                                g.m_y = 1 ' To move 1-row down.
                            END IF
                            IF _KEYDOWN(19200) THEN ' Left-arrow.
                                g.m_x = -1 ' To move 1-column left.
                            END IF

                            IF g.m_x AND g.m_y THEN ' Double key hold. Routine to cancel keys when double hold is lifted. Compensates for both keys not being released at exactly the same time.
                                combo = -1 ' Double key hold in progress.
                            ELSE
                                IF combo THEN combo = 0: v.kb_access = 0: EXIT DO ' Double key hold was just removed, so skip Guardian move and exit.
                            END IF
                        END IF
                    END IF

                    ' Move Guardian. *****************************************************************************************************
                    IF g.y + g.m_y > v.top AND g.y + g.m_y <= v.bottom AND g.x + 2 * g.m_x > v.left AND g.x + 2 * g.m_x < v.right THEN
                        LOCATE g.y, g.x
                        PRINT " ";
                        g.y = g.y + g.m_y: g.x = g.x + 2 * g.m_x
                        IF SCREEN(g.y, g.x) <> 32 AND SCREEN(g.y, g.x) <> g.m_asc THEN ' Guardian abducted by bad move. Ignore if you run into your own missile.
                            CALL guardian_abduction: EXIT SUB
                        ELSE
                            LOCATE g.y, g.x: PRINT g.flagship;
                        END IF
                    ELSE
                        ' Hit boundary.
                    END IF
                    v.kb_access = 0 ' Guardian move completed. Returns control to general keyboard next cycle.
                    z2 = TIMER ' Timer for moving. Lag regulated by "g.thrusters" variable.
                    EXIT DO ' ************************************************************************************************************
                LOOP
            END IF '
        ELSE ' If you want additional key routines, put them here...------------------------------------------------------------------------------------------------------------------
            CALL mouse(mouse_event1, mouse_event2)
            ky$ = INKEY$
            IF mouse_event1 = -1 THEN ky$ = CHR$(9)
            IF LEN(ky$) = 1 THEN ' For demo, exclude keys that start with chr$(0). Note without this arrow keys would still register here.
                SELECT CASE ky$
                    CASE CHR$(9) ' Tab key. Bug note: Space bar will not register with arrow up + arrow v.left.
                        IF ABS(z8 - TIMER) > .25 THEN
                            SELECT CASE g.m_launcher
                                CASE ""
                                    IF mouse_event1 = -1 THEN g.m_launcher = "mouse" ELSE g.m_launcher = "keyboard" ' Initiate.
                                CASE "keyboard"
                                    IF mouse_event1 = -1 THEN
                                        IF g.m_fired = 0 THEN
                                            g.m_launcher = "mouse" ' Switch.
                                        ELSE
                                            ky$ = ""
                                        END IF
                                    END IF
                                CASE "mouse"
                                    IF mouse_event1 = 0 THEN ' Tab key was used.
                                        IF g.m_fired = 0 THEN
                                            g.m_launcher = "keyboard" ' Switch
                                        ELSE
                                            ky$ = ""
                                        END IF
                                    END IF
                            END SELECT
                            IF LEN(ky$) THEN
                                g.m_status = -1 ' -1 indicates missile just fired.
                                IF mouse_event1 = 0 THEN v.mouse_or_key_move = 0: ' Key pressed missile fire clears any previous mouse button missile fire.
                            END IF
                            mouse_event1 = 0 ' Completes left mouse missile firing cycle.
                            z8 = TIMER ' Missile firing delay reset.
                        END IF
                    CASE CHR$(27) ' Esc
                        _DELAY 1: SYSTEM
                    CASE ELSE
                        REM PRINT "You pressed key: "; ky$;
                END SELECT
            END IF
        END IF '----------------------------------------------------------------------------------------------------------------------------------------------------------------------
    LOOP
END SUB

SUB comm
    STATIC middle% ' Local variable.
    IF middle% = 0 THEN middle% = v.left + (v.right - v.left) \ 2
    REM msg$ = "  Thrusters = " + LTRIM$(STR$(5 * (20 - g.thrusters))) + "%  Fired = " + LTRIM$(STR$(g.m_fired)) + " Alien ships = " + LTRIM$(STR$(a.count)) + " Level = " + LTRIM$(STR$(v.level)) + "-" + LTRIM$(STR$(g.difficulty)) + " Guardians: "
    msg$ = "  Population = " + LTRIM$(STR$(g.population)) + " Thrusters = " + LTRIM$(STR$(5 * (20 - g.thrusters))) + "%  Fired = " + LTRIM$(STR$(g.m_fired)) + " Alien ships = " + LTRIM$(STR$(a.count)) + " Level = " + LTRIM$(STR$(v.level)) + "-" + LTRIM$(STR$(g.difficulty)) + " Guardians: "
    LOCATE 1, v.left + middle% - ((LEN(msg$) + 8) \ 2): PRINT msg$;
    SELECT CASE g.num
        CASE 3
            PRINT g.icon; " "; g.icon; " "; g.icon;
        CASE 2
            PRINT g.icon; " "; g.icon; " ";: COLOR 8, 0: PRINT g.icon;: COLOR 7, 0
        CASE 1
            PRINT g.icon; " ";: COLOR 8, 0: PRINT g.icon; " "; g.icon;: COLOR 7, 0
        CASE 0
            COLOR 8, 0: PRINT g.icon; " "; g.icon; " "; g.icon; " ";: COLOR 7, 0
    END SELECT
    PRINT "   "; ' Cut off any former printing caused by length changes in comm report like when numbers change from double to single digits.
END SUB

SUB Guardian_missiles
    STATIC z4

    DIM direction AS INTEGER ' 8 possible directions. local variable.

    IF ABS(z4 - TIMER) > .03 THEN
        z4 = TIMER
        IF v.mouse_or_key_move = 0 THEN ' GAME OPTION: Remove this first IF/THEN to make it necessary to move  Guardian in a direction to fire in that direction.
            IF g.m_y <> 0 OR g.m_x <> 0 THEN g.diry = g.m_y: g.dirx = g.m_x ' Initiate by setting row and column missile direction to last column and row movement direction of Guardian location.
        END IF
        IF g.m_status = -1 THEN
            IF g.diry = -1 AND g.dirx = 0 THEN
                direction = 1
            ELSEIF g.diry = -1 AND g.dirx = 1 THEN
                direction = 2
            ELSEIF g.diry = 0 AND g.dirx = 1 THEN
                direction = 3
            ELSEIF g.diry = 1 AND g.dirx = 1 THEN
                direction = 4
            ELSEIF g.diry = 1 AND g.dirx = 0 THEN
                direction = 5
            ELSEIF g.diry = 1 AND g.dirx = -1 THEN
                direction = 6
            ELSEIF g.diry = 0 AND g.dirx = -1 THEN
                direction = 7
            ELSEIF g.diry = -1 AND g.dirx = -1 THEN
                direction = 8
            END IF

            IF m_n(direction) + 1 <= g.m_max THEN ' Don't fire if out of missiles.
                IF g.y > v.top + 1 AND g.y < v.bottom AND g.x > v.left + 1 AND g.x < v.right - 1 THEN ' Don't fire if at a border.
                    m_n(direction) = m_n(direction) + 1
                    m_y(m_n(direction), direction) = g.y
                    m_x(m_n(direction), direction) = g.x
                    g.m_fired = g.m_fired + 1
                    SOUND 900, .1
                END IF
            END IF
            g.m_status = 1 ' Code will now execute missile launch.
        END IF

        IF g.m_status = 1 THEN
            FOR g.m_d = 1 TO 8 ' Check all directions.
                IF m_n(g.m_d) > 0 THEN
                    j = m_n(g.m_d)
                    FOR g.m_n = 1 TO j
                        IF m_y(g.m_n, g.m_d) = g.y AND m_x(g.m_n, g.m_d) = g.x THEN
                        ELSE
                            LOCATE m_y(g.m_n, g.m_d), m_x(g.m_n, g.m_d): PRINT " ";
                        END IF
                        SELECT CASE g.m_d ' Missile direction.
                            CASE 1
                                IF m_y(g.m_n, g.m_d) - 1 > v.top THEN
                                    m_y(g.m_n, g.m_d) = m_y(g.m_n, g.m_d) - 1
                                    CALL missile_check(k): IF k = -1 THEN EXIT FOR
                                ELSE
                                    CALL remove_missile: EXIT FOR ' Missile off screen.
                                END IF
                            CASE 2
                                IF m_y(g.m_n, g.m_d) - 1 > v.top AND m_x(g.m_n, g.m_d) + 2 < v.right THEN
                                    m_y(g.m_n, g.m_d) = m_y(g.m_n, g.m_d) - 1
                                    m_x(g.m_n, g.m_d) = m_x(g.m_n, g.m_d) + 2
                                    CALL missile_check(k): IF k = -1 THEN EXIT FOR
                                ELSE
                                    CALL remove_missile: EXIT FOR
                                END IF
                            CASE 3
                                IF m_x(g.m_n, g.m_d) + 2 < v.right THEN
                                    m_x(g.m_n, g.m_d) = m_x(g.m_n, g.m_d) + 2
                                    CALL missile_check(k): IF k = -1 THEN EXIT FOR
                                ELSE
                                    CALL remove_missile: EXIT FOR
                                END IF
                            CASE 4
                                IF m_y(g.m_n, g.m_d) + 1 < v.bottom AND m_x(g.m_n, g.m_d) + 2 < v.right THEN
                                    m_y(g.m_n, g.m_d) = m_y(g.m_n, g.m_d) + 1
                                    m_x(g.m_n, g.m_d) = m_x(g.m_n, g.m_d) + 2
                                    CALL missile_check(k): IF k = -1 THEN EXIT FOR
                                ELSE
                                    CALL remove_missile: EXIT FOR
                                END IF
                            CASE 5
                                IF m_y(g.m_n, g.m_d) + 1 < v.bottom THEN
                                    m_y(g.m_n, g.m_d) = m_y(g.m_n, g.m_d) + 1
                                    CALL missile_check(k): IF k = -1 THEN EXIT FOR
                                ELSE
                                    CALL remove_missile: EXIT FOR
                                END IF
                            CASE 6
                                IF m_y(g.m_n, g.m_d) + 1 < v.bottom AND m_x(g.m_n, g.m_d) - 2 > v.left THEN
                                    m_y(g.m_n, g.m_d) = m_y(g.m_n, g.m_d) + 1
                                    m_x(g.m_n, g.m_d) = m_x(g.m_n, g.m_d) - 2
                                    CALL missile_check(k): IF k = -1 THEN EXIT FOR
                                ELSE
                                    CALL remove_missile: EXIT FOR
                                END IF
                            CASE 7
                                IF m_x(g.m_n, g.m_d) - 2 > v.left THEN
                                    m_x(g.m_n, g.m_d) = m_x(g.m_n, g.m_d) - 2
                                    LOCATE m_y(g.m_n, g.m_d), m_x(g.m_n, g.m_d)
                                    CALL missile_check(k): IF k = -1 THEN EXIT FOR
                                ELSE
                                    CALL remove_missile: EXIT FOR
                                END IF
                            CASE 8
                                IF m_y(g.m_n, g.m_d) - 1 > v.top AND m_x(g.m_n, g.m_d) - 2 > v.left THEN
                                    m_y(g.m_n, g.m_d) = m_y(g.m_n, g.m_d) - 1
                                    m_x(g.m_n, g.m_d) = m_x(g.m_n, g.m_d) - 2
                                    CALL missile_check(k): IF k = -1 THEN EXIT FOR
                                ELSE
                                    CALL remove_missile: EXIT FOR
                                END IF
                        END SELECT
                    NEXT
                    IF a.count = 0 THEN EXIT SUB
                END IF
            NEXT
            IF g.m_fired <= 0 THEN g.m_fired = 0: g.m_status = 0 ' All missiles cleared.
        END IF
    END IF
END SUB

SUB missile_check (k)
    LOCATE m_y(g.m_n, g.m_d), m_x(g.m_n, g.m_d) ' Place cursor at current missile position.
    k = SCREEN(m_y(g.m_n, g.m_d), m_x(g.m_n, g.m_d)) ' Read the screen.
    id_by_color = SCREEN(m_y(g.m_n, g.m_d), m_x(g.m_n, g.m_d), 1)
    IF k <> 32 AND k <> g.m_asc AND k <> ASC(g.flagship) THEN ' If screen space is occupied by alien ship then explosion.
        CALL remove_missile
        CALL explosion
        REM Game Option - IF SCREEN(g.y, g.x) <> ASC(g.flagship) THEN BEEP: BEEP: BEEP
        CALL remove_ship(id_by_color)
        k = -1 ' A flag to exit the FOR/NEXT loop upon return.
    ELSE
        COLOR 14: PRINT CHR$(g.m_asc);: COLOR 7 ' Print missile on the screen. Missile advances here. Only place a missile is printed to the screen.
    END IF
END SUB

SUB remove_missile
    m_n(g.m_d) = m_n(g.m_d) - 1 ' Counter. Reduce the number of missiles fired, in a specific direction, by 1.
    FOR k = g.m_n TO m_n(g.m_d) ' Re-stack arrays.
        m_y(k, g.m_d) = m_y(k + 1, g.m_d)
        m_x(k, g.m_d) = m_x(k + 1, g.m_d)
    NEXT
    m_y(k, g.m_d) = 0: m_x(k, g.m_d) = 0 'Zero out location variables of the missile removed. A zero removes unnecessary loop checking for other routines.
    g.m_fired = g.m_fired - 1 ' Count of number of missiles fired is reduce by 1.
END SUB

SUB mask_missiles
    FOR i = 1 TO g.m_max
        FOR j = 1 TO 8
            IF m_y(i, j) <> 0 THEN LOCATE m_y(i, j), m_x(i, j): PRINT " "; ' Mask missile.
    NEXT j, i
    m_status = 0: m_fired = 0: m_n = 0: m_d = 0: m_y = 0: m_x = 0
    REDIM m_n(8), m_x(g.m_max, 8), m_y(g.m_max, 8)
END SUB

SUB explosion
    soundfile% = 1 ' Local variable turns sound on.
    b_y1 = CSRLIN: b_x1 = POS(0)
    VIEW PRINT v.top TO v.bottom ' Needed to set print error parameters.
    h = 0
    ON ERROR GOTO offscreen
    DO
        IF h = 1 THEN burst$ = " " ELSE burst$ = CHR$(249)
        IF v.intro THEN burst$ = "" ' No fireworks, just flash and sound.
        h = h + 1
        ' Flash
        IF eflag THEN
            IF ABS(z7 - TIMER) > .1 THEN
                eflag = 0
                PALETTE 0, 0
                z7 = TIMER
            ELSE
                j = -j * -1
                IF j = 0 THEN
                    PALETTE 0, 63
                    _DELAY .05
                ELSE
                    PALETTE 0, 0
                    _DELAY .05
                END IF
            END IF
        END IF
        IF eflag = 0 THEN
            PALETTE 0, 36
            IF soundfile% THEN
                _SNDPLAY v.snd1
                _DELAY .05
                PALETTE 0, 0
                _SNDPLAY v.snd2
            ELSE
                _DELAY .075
            END IF
            eflag = -1
            z7 = TIMER
        END IF
        PALETTE 0, 0 ' End flash.

        FOR i = 1 TO 5
            SELECT CASE i
                CASE 1
                    COLOR 15
                    LOCATE b_y1, b_x1: PRINT burst$;
                    _DELAY .1
                CASE 2
                    IF burst$ = CHR$(249) THEN burst$ = CHR$(250)
                    COLOR 14, 0
                    LOCATE b_y1 - 1, b_x1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1, b_x1 - 1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1, b_x1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1, b_x1 + 1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1 + 1, b_x1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    _DELAY .1
                CASE 3
                    LOCATE b_y1 - 1, b_x1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1, b_x1 - 1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1, b_x1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1, b_x1 + 1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1 + 1, b_x1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                CASE 4
                    COLOR 4
                    LOCATE b_y1 - 1, b_x1 - 1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1 - 1, b_x1 + 1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1, b_x1 - 2
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1, b_x1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1, b_x1 + 2
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1 + 1, b_x1 - 1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    LOCATE b_y1 + 1, b_x1 + 1
                    IF er = 0 THEN PRINT burst$; ELSE er = 0
                    _DELAY .3
                CASE 5
                    LOCATE b_y1 - 1, b_x1 - 1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1 - 1, b_x1 + 1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1, b_x1 - 2
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1, b_x1 - 1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1, b_x1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1, b_x1 + 1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1, b_x1 + 2
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1 + 1, b_x1 - 1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
                    LOCATE b_y1 + 1, b_x1 + 1
                    IF er = 0 THEN PRINT " "; ELSE er = 0
            END SELECT
        NEXT
        IF h = 1 THEN h = 0: EXIT DO
    LOOP
    VIEW PRINT
    ON ERROR GOTO 0
    COLOR 7
    IF a.count = 1 THEN CALL mask_missiles ' Clear unexploded missiles off the screen when changing levels. Game Option: Remove variable to mask missiles after every explosion.
    LOCATE b_y1, b_x1
END SUB

SUB remove_ship (id_by_color) ' Removes ship by color identification.
    i = a.itr
    ON ERROR GOTO offscreen
    LOCATE a_mask_y(id_by_color), a_mask_x(id_by_color): PRINT SPACE$(LEN(a.ship));
    LOCATE a_y(id_by_color), a_x(id_by_color): PRINT SPACE$(LEN(a.ship));
    ON ERROR GOTO 0
    a.itr = id_by_color: CALL a_erase
    a_ran(id_by_color) = -1 ' Denotes alien ship was destroyed and removed from battle.
    a.itr = i
    a.count = a.count - 1 ' a.count = 0  will cause program to exit any unneeded subs/loops after the game level sub is completed.
    LOCATE g.y, g.x: PRINT g.flagship; ' Re-display Guardian.
    ' Restore any alien ships in blast zone.
    FOR i = 1 TO a.max
        IF a_ran(i) > 0 THEN
            IF a_y(i) > v.top AND a_x(i) > v.left AND a_x(i) + LEN(a.ship) < v.right THEN LOCATE a_y(i), a_x(i): COLOR i: PRINT a.ship;
        END IF
    NEXT
    COLOR 7
    CALL comm
END SUB

SUB alien_move
    STATIC z5
    y_restore = CSRLIN: x_restore = POS(0) ' Restore column and row upon exit.
    IF ABS(z5 - TIMER) > a.cycle_delay OR v.intro THEN ' z5 is a time delay for alien space ship maneuvers. It can be altered in the "game" subroutine.
        IF v.intro = 0 THEN h_alien_nom = INT(RND * a.max) + 1 ELSE h_alien_nom = 15
        FOR h = 1 TO h_alien_nom ' Local counting variable for alien number of moves in this cycle.
            a.itr = a.itr + 1: IF a.itr > a.max THEN a.itr = 1 ' Needed to offset the EXIT DO hover event, which on exit does not affect the a.itr variable.
            IF a_ran(a.itr) <> -1 THEN ' This is how a destroyed ship is bypassed. -1 is a destroyed alien ship. Code moves to end of DO:LOOP.
                IF a_inertia(a.itr) = 0 THEN ' Determine how many moves in one direction.
                    a_inertia(a.itr) = INT(RND * (v.bottom - v.top) / 2) + 1 ' How many moves to go in any one direction.
                    a_ran(a.itr) = INT(RND * 8) + 1 ' Choose 1 of 8 possible directions.

                    IF a_ran(a.itr) = a_olda_ran(a.itr) OR a_mask_y(a.itr) = 0 AND a_mask_x(a.itr) = 0 AND ran = 1 OR a_mask_y(a.itr) = 0 AND a_mask_x(a.itr) = 0 AND ran = 5 THEN
                        EXIT FOR ' Just hover if direction was not changed on existing alien space ship or if a new alien space ship is entering from the sides and up or down was generated.
                    END IF

                    SELECT CASE a_ran(a.itr) ' Get changes in column and row coordinates.
                        CASE 1: a_y_loc(a.itr) = -1: a_x_loc(a.itr) = 0 '  Up.
                        CASE 2: a_y_loc(a.itr) = -1: a_x_loc(a.itr) = 2 '  Up and right.
                        CASE 3: a_y_loc(a.itr) = 0: a_x_loc(a.itr) = 2 '   Right.
                        CASE 4: a_y_loc(a.itr) = 1: a_x_loc(a.itr) = 2 '   Down and right.
                        CASE 5: a_y_loc(a.itr) = 1: a_x_loc(a.itr) = 0 '   Down.
                        CASE 6: a_y_loc(a.itr) = 1: a_x_loc(a.itr) = -2 '  Down and left.
                        CASE 7: a_y_loc(a.itr) = 0: a_x_loc(a.itr) = -2 '  Left.
                        CASE 8: a_y_loc(a.itr) = -1: a_x_loc(a.itr) = -2 ' Up and left.
                    END SELECT

                    IF a_y(a.itr) = 0 AND a_x(a.itr) = 0 AND a_ran(a.itr) <> -1 THEN ' New alien space ship enters the screen.
                        i = RND * (v.bottom - v.top) \ 4
                        a_y(a.itr) = (v.bottom - v.top) \ 4 + i + v.top
                        IF a_ran(a.itr) < 5 THEN ' Determine side of entry from initial direction.
                            IF SCREEN(a_y(a.itr), v.left + LEN(a.ship)) = 32 THEN
                                a_x(a.itr) = v.left + 1 ' Enter from the left side and go right.
                            ELSE
                                CALL a_erase
                                EXIT FOR
                            END IF
                        ELSE
                            IF SCREEN(a_y(a.itr), v.right - LEN(a.ship) + 1) = 32 THEN
                                a_x(a.itr) = v.right - LEN(a.ship) ' Enter from the right side and go left.
                            ELSE
                                CALL a_erase
                                EXIT FOR
                            END IF
                        END IF
                    END IF
                    a_olda_ran(a.itr) = a_ran(a.itr) ' Remember last direction. Another line uses this to disallow any RND that chooses the same direction twice.
                ELSE
                    a_inertia(a.itr) = a_inertia(a.itr) - 1 ' Count down the number of moves in any one direction. When zero, switch direction.
                END IF

                FOR i = 1 TO a.max
                    IF i <> a.itr AND a_y(i) <> 0 THEN
                        IF a_y(a.itr) + a_y_loc(a.itr) = a_y(i) THEN
                            IF a_x(a.itr) + a_x_loc(a.itr) + LEN(a.ship) > a_x(i) AND a_x(a.itr) + a_x_loc(a.itr) < a_x(i) + LEN(a.ship) THEN
                                collide = 1
                                EXIT FOR
                            END IF
                        END IF
                    END IF
                NEXT
                IF collide = 1 THEN
                    j = a_y(a.itr): k = a_x(a.itr)
                    a_y_loc(a.itr) = 0: a_x_loc(a.itr) = 0: a_inertia(a.itr) = 0
                    collide = 0 ' Collision detection off. Collision was detected and avoided.
                ELSE
                    j = a_y(a.itr) + a_y_loc(a.itr): k = a_x(a.itr) + a_x_loc(a.itr)
                END IF

                IF j <= v.top OR k <= v.left OR k + LEN(a.ship) > v.right THEN ' Alien ship out of range, off screen.
                    a_inertia(a.itr) = 0 ' These two lines keep the out of range ship(s) reasonably nearby.
                    IF j > v.top - 4 AND k < v.right + 3 AND k > v.left - 4 THEN a_y(a.itr) = j: a_x(a.itr) = k
                    IF a_mask_y(a.itr) <> 0 AND a_mask_x(a.itr) <> 0 THEN
                        LOCATE a_mask_y(a.itr), a_mask_x(a.itr)
                        PRINT SPACE$(LEN(a.ship)); ' Mask old position here because the show part of the mask-and-show routine cannot be used when out of range.
                    END IF
                    IF a_offscrn(a.itr) > 25 THEN a_y(a.itr) = 0: a_x(a.itr) = 0: a_inertia(a.itr) = 0: a_offscrn(a.itr) = 0
                    a_mask_y(a.itr) = 0: a_mask_x(a.itr) = 0: a_offscrn(a.itr) = a_offscrn(a.itr) + 1
                ELSE
                    ' Check for v.bottom collision and reverse course if detected.
                    COLOR a.itr
                    IF j >= v.bottom THEN
                        IF j = v.bottom AND k > v.left + 10 AND k < v.right - 10 THEN
                            LOCATE a_y(a.itr) + 1, a_x(a.itr)
                            COLOR 15 + 16: PRINT "-500";
                            g.population = g.population - 500
                            SOUND 300, .2: _DELAY .07: SOUND 600, .2: _DELAY .07: SOUND 400, .2
                            COLOR 7
                            CALL comm
                            LOCATE a_y(a.itr) + 1, a_x(a.itr)
                            PRINT SPACE$(5);
                            a_inertia(a.itr) = v.bottom - v.top
                            a_y_loc(a.itr) = -a_y_loc(a.itr): a_x_loc(a.itr) = -a_x_loc(a.itr)
                            a_y_loc(a.itr) = -1
                        ELSE
                            a_y_loc(a.itr) = -a_y_loc(a.itr): a_x_loc(a.itr) = -a_x_loc(a.itr)
                        END IF
                    ELSE
                        a_y(a.itr) = j: a_x(a.itr) = k ' Next move coordinates.
                        ii = 0
                        kk = ASC(g.flagship)
                        FOR i = 0 TO LEN(a.ship) - 1 ' Check area through width of ship. Remember all or parts of ship are still present on screen.
                            SELECT CASE SCREEN(j, k + i)
                                CASE kk
                                    ii = 1 ' Indicates contact with flagship and evokes call abduction routine a few lines down.
                                    EXIT FOR
                                CASE g.m_asc
                                    ii = 2 ' Indicates ship into missile collision.
                                    EXIT FOR 'Okay to exit as a missile and Guardian craft cannot be present in the same location.
                            END SELECT
                        NEXT
                        IF ii <> 2 THEN ' This will make a move unless a ship into missile event would occur.
                            '--------------------------------------------Move alien ship-------------------------------------------------
                            IF a_mask_y(a.itr) <> 0 AND a_mask_x(a.itr) <> 0 THEN LOCATE a_mask_y(a.itr), a_mask_x(a.itr): PRINT SPACE$(LEN(a.ship));
                            LOCATE j, k: PRINT a.ship;
                            a_mask_y(a.itr) = j: a_mask_x(a.itr) = k ' Remember these coordinates to erase alien space ship on next loop.
                            '------------------------------------------------------------------------------------------------------------
                        END IF
                        IF ii = 1 THEN CALL guardian_abduction: EXIT FOR ' Exit loop.
                        j = j - g.y: k = k - g.x + LEN(a.ship) / 2
                        IF ABS(j) < 3 AND ABS(k) < 8 THEN CALL a_hunt(j, k)
                    END IF
                    COLOR 7
                END IF
            END IF ' a_ran(a.itr) > -1 exit point.
            IF a.itr = a.max THEN a.itr = 0: EXIT FOR ' Finished loop. Keep this outside the IF/THEN statement.
        NEXT h
        z5 = TIMER
        LOCATE y_restore, x_restore ' Restore entry column and row positions.
    END IF ' End time event.
END SUB

SUB guardian_abduction

    IF v.intro = 0 THEN
        CALL mask_missiles ' Clear unexploded missiles off the screen after alien abduction.

        msg$ = "[GUARDIAN ABDUCTED]"
        SOUND 500, .4: SOUND 1000, .3: SOUND 1500, .2
        PCOPY 0, 1
        SCREEN 0, 0, 1, 1
        LOCATE (v.bottom - v.top) \ 2 + v.top, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
        COLOR 14 + 16: PRINT msg$;
        _DELAY 2
        SCREEN 0, 0, 0, 0
    END IF

    DO
        j = 0
        FOR i = 1 TO a.max
            IF a_y(i) >= v.top AND a_x(i) >= v.left AND a_x(i) <= v.right - LEN(a.ship) THEN
                SOUND 500, .04
                LOCATE a_y(i), a_x(i): PRINT SPACE$(LEN(a.ship));
                IF a_y(i) <> v.top THEN a_y(i) = a_y(i) - 1: LOCATE a_y(i), a_x(i): COLOR i: PRINT a.ship;: _DELAY .02: j = 1
            END IF
        NEXT
    LOOP WHILE j
    COLOR 7
    IF v.intro THEN EXIT SUB
    g.num = g.num - 1
    CALL comm
    _DELAY .75
    v.redo_level = -1
    a.count = 0 ' Zero to exit subs back to main game loop.
END SUB

SUB game_level ' Evaluates both alien defeated on a level and Guardian abduction.
    _DELAY .5
    VIEW PRINT v.top TO v.bottom: CLS 2: VIEW PRINT
    _DELAY .5
    msg$ = "[LEVEL " + LTRIM$(STR$(v.level)) + "]"
    LOCATE (v.bottom - v.top) \ 2 + v.top, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
    COLOR 14 + 16: PRINT msg$;
    j = 0: k = 0
    DO
        IF ABS(z0 - TIMER) > .15 THEN
            IF j = 0 THEN j = 1: SOUND 750, .3: k = k + 1 ELSE j = 0: _DELAY .1
            z0 = TIMER
        END IF
    LOOP UNTIL k = 6
    COLOR 7
    LOCATE , v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
    PRINT msg$;
    VIEW PRINT v.top TO v.bottom: CLS 2: VIEW PRINT
    _DELAY .75
    CALL comm
    g.y = (v.bottom - v.top) \ 2 + v.top: g.x = (v.right - v.left + 1) \ 2 + v.left ' Reset column and row for Guardian craft.
    LOCATE g.y, g.x
    COLOR 15 + 16: PRINT g.flagship;
    _DELAY 1.5
    COLOR 7: LOCATE g.y, g.x: PRINT g.flagship;
    v.level_up = -1
END SUB

SUB level_up
    v.level = v.level + 1
END SUB

SUB a_erase
    a_y(a.itr) = 0: a_x(a.itr) = 0: a_mask_y(a.itr) = 0: a_mask_x(a.itr) = 0: a_inertia(a.itr) = 0: a_ran(a.itr) = 0: a_y_loc(a.itr) = 0: a_x_loc(a.itr) = 0: a_olda_ran(a.itr) = 0
END SUB

SUB mouse (mouse_event1, mouse_event2)
    STATIC z9, z10, lb, lb_status ' lb_status keeps track of press/release.
    WHILE _MOUSEINPUT
        IF ABS(z10 - TIMER) > .1 THEN
            z10 = TIMER
            IF _MOUSEWHEEL > 0 THEN ' Down
                IF g.thrusters < 20 THEN g.thrusters = g.thrusters + 1
            ELSEIF _MOUSEWHEEL < 0 THEN ' Up
                IF g.thrusters > 0 THEN g.thrusters = g.thrusters - 1
            END IF
        END IF
    WEND
    mx = _MOUSEX
    my = _MOUSEY
    lb = _MOUSEBUTTON(1)
    rb = _MOUSEBUTTON(2)

    IF lb THEN
        IF lb_status = 0 THEN
            IF ABS(z9 - TIMER) > .33 THEN
                z9 = TIMER
                mouse_event1 = -1: lb_status = -1: ' Left button down
            END IF
        END IF
    ELSE
        IF lb_status THEN lb_status = 0 ' Left button was released.
    END IF

    IF v.mouse_get_screen THEN
        IF lb_status = -1 THEN
            x$ = CHR$(SCREEN(my, mx))
            SELECT CASE v.mouse_get_screen
                CASE 1 ' Select difficulty.
                    SELECT CASE x$
                        CASE "1"
                            g.difficulty = 1
                        CASE "2"
                            g.difficulty = 2
                        CASE "3"
                            g.difficulty = 3
                        CASE "S" ' Skip intro.
                            IF x$ = "S" THEN v.intro = 999: SOUND 1000, .3: EXIT SUB
                    END SELECT
                CASE 2 ' Replay
                    IF x$ = "Y" THEN v.play = 999: SOUND 1000, .1: EXIT SUB
                    IF x$ = "N" THEN v.play = -999: SOUND 1000, .1: EXIT SUB
            END SELECT
        END IF
    END IF
    cx = g.x: cy = g.y ' Angular calculations provided by bplus from the QB64 Phoenix Forum.
    stepX = ABS(cx - mx): stepY = ABS(cy - my)

    dAng = INT(_R2D(_ATAN2(my - cy, mx - cx)) + .5)
    IF dAng < 0 THEN dAng = dAng + 360

    IF dAng <= 90 THEN
        startA = 0: endA = dAng: ra = dAng
    ELSEIF dAng <= 180 THEN
        startA = dAng: endA = 180: ra = 90 - (dAng - 90)
    ELSEIF dAng <= 270 THEN
        startA = 180: endA = dAng: ra = dAng - 180
    ELSEIF dAng <= 360 THEN
        startA = dAng: endA = 360: ra = 90 - (dAng - 270)
    END IF

    m_y = 0: m_x = 0
    IF ra <= 90 AND ra >= 50 THEN
        IF my > g.y THEN
            x$ = "down": m_y = 1: m_x = 0 ' Down.
        ELSE
            x$ = "up": m_y = -1: m_x = 0 ' Up.
        END IF
    ELSEIF ra < 50 AND ra >= 15 THEN
        IF mx > g.x AND my > g.y THEN
            x$ = "down right": m_y = 1: m_x = 2 ' Down and right.
        ELSEIF mx < g.x AND my > g.y THEN
            x$ = "down left": m_y = 1: m_x = -2 ' Down an left.
        ELSEIF mx > g.x AND my < g.y THEN
            x$ = "up right": m_y = -1: m_x = 2 ' Up and right.
        ELSEIF mx < g.x AND my < g.y THEN
            x$ = "up left": m_y = -1: m_x = -2 ' Up and left.
        END IF
    ELSEIF ra < 15 AND ra >= 0 THEN
        IF mx > g.x THEN
            x$ = "right": m_y = 0: m_x = 2 ' Right
        ELSE
            x$ = "left": m_y = 0: m_x = -2 ' Left
        END IF
    END IF

    IF rb AND mouse_event2 = 0 THEN
        mouse_event2 = -1
        g.m_y = m_y: g.m_x = m_x / 2
        v.mouse_or_key_move = 1 ' Right mouse button to move.
    ELSE
        IF mouse_event2 THEN mouse_event2 = 0
    END IF

    IF mouse_event1 THEN
        g.diry = m_y: g.dirx = m_x / 2
        v.mouse_or_key_move = -1
    END IF
END SUB

SUB game_over
    v.mouse_get_screen = 2 ' Allows mouse to select replay options.
    _DELAY .5
    CALL comm
    IF g.num THEN SOUND 1000, .75: SOUND 500, .75: SOUND 1000, 1.5 ELSE SOUND 1000, .75: SOUND 700, .75: SOUND 500, 1.5
    _DELAY .5
    VIEW PRINT v.top TO v.bottom: CLS 2: VIEW PRINT
    IF g.num THEN msg$ = "[GUARDIAN WINS]" ELSE msg$ = "[Game Over]"
    LOCATE (v.bottom - v.top) \ 2 + v.top - 1, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
    COLOR 14 + 16
    PRINT msg$;
    _DELAY 2
    IF g.num > 0 THEN
        LOCATE (v.bottom - v.top) \ 2 + v.top - 1, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
        COLOR 7
        PRINT SPACE$(LEN(msg$));
        CALL displayhighscores
    ELSE
        FOR i = 1 TO 2
            LOCATE v.bottom, v.left + ((v.right - v.left + 1) \ 2)
            CALL explosion
        NEXT
        LOCATE v.bottom + 1, v.left
        COLOR 8
        PRINT STRING$(v.right - v.left + 1, "÷");
        COLOR 7
        _DELAY .3
        g.population = 0
        CALL comm
        _DELAY .5
    END IF
    LOCATE (v.bottom - v.top) \ 2 + v.top - 1, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
    COLOR 14: PRINT msg$;
    msg$ = "Replay? Y/N"
    _DELAY 1
    LOCATE (v.bottom - v.top) \ 2 + v.top + 1, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
    COLOR 8
    PRINT msg$;
    COLOR 7
    DO
        _LIMIT 30
        CALL mouse(mouse_event1, mouse_event2)
        ky$ = INKEY$
        IF LEN(ky$) OR ABS(v.play) = 999 THEN
            IF v.play = 999 OR UCASE$(ky$) = "Y" OR ky$ = CHR$(13) THEN v.play = 1: VIEW PRINT v.top TO v.bottom: CLS 2: VIEW PRINT: EXIT DO
            IF v.play = -999 OR UCASE$(ky$) = "N" OR ky$ = CHR$(27) THEN
                msg$ = "   [Bye Bye]   "
                LOCATE (v.bottom - v.top) \ 2 + v.top - 1, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
                COLOR 14 + 16: PRINT msg$;
                _DELAY 1
                LOCATE (v.bottom - v.top) \ 2 + v.top - 1, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
                COLOR 14: PRINT msg$;
                _DELAY .5
                LOCATE (v.bottom - v.top) \ 2 + v.top + 1, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
                PRINT SPACE$(LEN(msg$));
                COLOR 14
                msg$ = "   [Bye Bye]   "
                LOCATE (v.bottom - v.top) \ 2 + v.top - 1, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
                DO
                    LOCATE , v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
                    SOUND 500, .04
                    PRINT SPACE$(LEN(msg$));
                    LOCATE CSRLIN - 1, v.left + ((v.right - v.left + 1) \ 2) - LEN(msg$) \ 2
                    PRINT msg$;
                    _DELAY .05
                LOOP UNTIL CSRLIN = v.top
                COLOR 7
                VIEW PRINT v.top TO v.bottom: CLS 2
                _DELAY .6
                SYSTEM
            END IF
        END IF
    LOOP
END SUB

SUB a_hunt (j, k)
    SELECT CASE a.ai
        CASE 0: EXIT SUB ' No hunting for level 1.
        CASE 1: IF RND * 99 < 33 THEN EXIT SUB ' Reduces chances of abduction for level 2.
    END SELECT
    LOCATE 3, 1
    a_inertia(a.itr) = 4
    h = j / ABS(j): i = k / ABS(k)
    SELECT CASE h
        CASE IS < 0 ' Ship above Guardian.
            SELECT CASE i
                CASE IS < 0 ' Ship to left of Guardian.
                    a_y_loc(a.itr) = 1: a_x_loc(a.itr) = 1
                CASE 0 ' Ship same column as Guardian.
                    a_y_loc(a.itr) = 1: a_x_loc(a.itr) = 0
                CASE IS > 0 ' Ship to right of Guardian.
                    a_y_loc(a.itr) = 1: a_x_loc(a.itr) = -1
            END SELECT
        CASE 0 ' Ship same row as Guardian.
            SELECT CASE i
                CASE IS < 0 ' Ship to left of Guardian.
                    a_y_loc(a.itr) = 0: a_x_loc(a.itr) = 1
                CASE IS > 0 ' Ship to right of Guardian.
                    a_y_loc(a.itr) = 0: a_x_loc(a.itr) = -1
            END SELECT
        CASE IS > 0 ' Ship below Guardian.
            SELECT CASE i
                CASE IS < 0 ' Ship to left of Guardian.
                    a_y_loc(a.itr) = -1: a_x_loc(a.itr) = 1
                CASE 0 ' Ship same column as Guardian.
                    a_y_loc(a.itr) = -1: a_x_loc(a.itr) = 0
                CASE IS > 0 ' Ship to right of Guardian.
                    a_y_loc(a.itr) = -1: a_x_loc(a.itr) = -1
            END SELECT
    END SELECT
    REM Game Option - Shields as a_y_loc(a.itr) = -a_y_loc(a.itr) : a_x_loc(a.itr) = -a_x_loc(a.itr)
END SUB

SUB city
    _CONTROLCHR OFF
    a$ = "_ê_ê_ê__²_²_²_²___ï_ï_ï___ê_ê___ããã______²_²___ê_ê_ê_"

    DO
        cityscape$ = cityscape$ + a$
    LOOP UNTIL LEN(cityscape$) > _WIDTH
    cityscape$ = MID$(cityscape$, 1, _WIDTH)
    LOCATE _HEIGHT, 1
    PRINT cityscape$;
END SUB

SUB displayhighscores
    hardware_top = v.top + 4
    hardware_left = v.left + 34
    score$ = LTRIM$(STR$(g.population))

    DIM hs AS STRING * 25
    REDIM highscore$(6), hsdata$(6)
    DO
        IF _FILEEXISTS("guardian-high-score.dat") THEN
            OPEN "guardian-high-score.dat" FOR RANDOM AS #1 LEN = 25
            FOR i = 1 TO 5
                GET #1, i, hs
                highscore$(i) = MID$(hs, 10, 6): hsdata$(i) = hs
            NEXT
            CLOSE #1
        ELSE
            FOR i = 1 TO 5
                hsdata$(i) = SPACE$(25)
            NEXT
        END IF

        IF VAL(score$) > VAL(highscore$(5)) THEN

            IF VAL(score$) > VAL(highscore$(1)) THEN
                topscore$ = "HIGH SCORE! Enter Initials!"
            ELSE
                topscore$ = "Top 5 Score Enter Initials!"
            END IF

            GOSUB hiscore

            i = 14
            OUT &H3C8, 0
            OUT &H3C9, 20 - i
            OUT &H3C9, 20 - i
            OUT &H3C9, 20 - i

            OUT &H3C8, 8
            OUT &H3C9, 30 - i
            OUT &H3C9, 30 - i
            OUT &H3C9, 30 - i

            OUT &H3C8, 7
            OUT &H3C9, 30 - i
            OUT &H3C9, 30 - i
            OUT &H3C9, 30 - i

            OUT &H3C8, 3
            OUT &H3C9, 30 - i
            OUT &H3C9, 30 - i
            OUT &H3C9, 30 - i

            GOSUB hardware_overlay

            COLOR White, 0
            t$ = msg$
            PSLC 4.6, 41 - LEN(msg$) \ 2, t$

            lscr = hardware_left + 6
            z3 = TIMER
            WHILE -1
                initials$ = "": i = 0: nxt = 0
                COLOR , _RGB(24, 24, 24): t$ = "   " ' Blank initials for redo. Okay to blank at start.
                PSL hardware_top + 2 + rank * 2, lscr, t$
                _DISPLAY
                DO
                    _LIMIT 30
                    IF ABS(z3 - TIMER) > .3 THEN ' Flashing cursor
                        underline hardware_top + 2 + rank * 2, lscr + nxt, 0
                        _DISPLAY
                        z3 = TIMER
                    END IF

                    ky$ = UCASE$(INKEY$)
                    IF LEN(ky$) THEN
                        IF ky$ = CHR$(13) THEN
                            kflag = 3
                        ELSEIF ky$ = CHR$(8) AND LEN(initials$) THEN
                            kflag = 2
                        ELSEIF ky$ = CHR$(27) THEN
                            kflag = 4
                        ELSEIF ky$ >= "A" AND ky$ <= "Z" AND LEN(initials$) < 3 THEN
                            initials$ = initials$ + ky$
                            kflag = 1
                        ELSE
                            ky$ = "": kflag = 0
                        END IF
                    END IF

                    SELECT CASE kflag
                        CASE 1
                            COLOR , _RGB(24, 24, 24)
                            PSL hardware_top + 2 + rank * 2, lscr + nxt, " "
                            COLOR Yellow
                            SOUND 1000, .1
                            PSL hardware_top + 2 + rank * 2, lscr + nxt, ky$
                            underline hardware_top + 2 + rank * 2, lscr + nxt, -1
                            nxt = nxt + 1
                            underline hardware_top + 2 + rank * 2, lscr + nxt, 0
                            _DISPLAY
                            kflag = 0
                        CASE 2
                            COLOR , _RGB(24, 24, 24)
                            underline hardware_top + 2 + rank * 2, lscr + nxt, -1
                            initials$ = MID$(initials$, 1, LEN(initials$) - 1)
                            nxt = nxt - 1
                            PSL hardware_top + 2 + rank * 2, lscr + nxt, " "
                            COLOR Yellow
                            SOUND 1000, .1
                            underline hardware_top + 2 + rank * 2, lscr + nxt, 0
                            _DISPLAY
                            kflag = 0
                        CASE 3
                            _DELAY 1
                            l$ = "12"
                            n$ = "n24": PLAY "L" + l$ + n$
                            n$ = "n28": PLAY "L" + l$ + n$
                            n$ = "n28": PLAY "L" + l$ + n$
                            l$ = "10"
                            n$ = "n31": PLAY "L" + l$ + n$
                            l$ = "12"
                            n$ = "n28": PLAY "L" + l$ + n$
                            l$ = "5"
                            n$ = "n31": PLAY "L" + l$ + n$
                            kflag = 1
                            _DELAY 1: EXIT DO
                        CASE 4
                            EXIT WHILE
                    END SELECT
                LOOP
                hsname$ = initials$

                MID$(hsdata$(rank), 5, 3) = hsname$ + SPACE$(3 - LEN(hsname$))
                OPEN "guardian-high-score.dat" FOR RANDOM AS #1 LEN = 25
                FOR i = 1 TO 5
                    hs = hsdata$(i)
                    IF LEFT$(hs, 1) = "" THEN MID$(hs, 1, 2) = "0" + LTRIM$(STR$(i))
                    PUT #1, i, hs
                NEXT
                CLOSE #1
                EXIT WHILE
            WEND

            _DISPLAY ' Remove scoreboard.
            _DELAY .5
            _FREEIMAGE Overlay

            _DEST 0 'Reset dest back to the normal screen 0.

            _AUTODISPLAY
            PALETTE
            _DELAY .5

            EXIT DO
        ELSE
            EXIT DO ' Not in the top 5 highest scores so exit sub.
        END IF
    LOOP
    EXIT SUB

    hardware_overlay:
    Overlay = _NEWIMAGE(_WIDTH * _FONTWIDTH, _HEIGHT * _FONTHEIGHT, 32)

    _DEST Overlay
    _DISPLAY ' Turn autodisplay off.

    font = _LOADFONT("lucon.ttf", 24, "monospace")
    IF font <= 0 THEN font = 16
    _FONT font

    bxy% = hardware_top
    bxx% = hardware_left

    COLOR White, 0
    PSL bxy% + .8, bxx% + 1, topscore$

    COLOR Yellow, 0
    t$ = " " + CHR$(218) + STRING$(27, CHR$(196)) + CHR$(191) + " "
    PSL bxy%, bxx% - 1, t$
    FOR i = 1 TO 12
        t$ = " " + CHR$(179) + STRING$(27, CHR$(32)) + CHR$(179) + " "
        PSL bxy% + i, bxx% - 1, t$
    NEXT
    t$ = " " + CHR$(192) + STRING$(27, CHR$(196)) + CHR$(217) + " "
    PSL bxy% + i, bxx% - 1, t$

    bxy% = hardware_top + 1
    COLOR Black, Yellow
    t$ = "    NAME   SCORE    DATE   "
    PSL bxy% + 1, bxx% + 1, t$

    COLOR Yellow, 0
    FOR i = 1 TO 5
        t$ = hsdata$(i)
        PSL bxy% + 1 + i * 2, bxx% + 2, t$
    NEXT
    _DISPLAY
    RETURN

    hiscore:
    FOR i = 1 TO 5
        IF VAL(score$) > VAL(highscore$(i)) THEN rank = i: EXIT FOR
    NEXT

    hsdata$(6) = SPACE$(25)
    MID$(hsdata$(6), 10, 6) = score$
    MID$(hsdata$(6), 18, 8) = MID$(DATE$, 1, 6) + MID$(DATE$, 9, 2)
    highscore$(6) = score$
    FOR i = 1 TO 6
        FOR j = 1 TO 6
            IF i <> j THEN
                IF VAL(highscore$(i)) > VAL(highscore$(j)) THEN
                    SWAP highscore$(i), highscore$(j)
                    SWAP hsdata$(i), hsdata$(j)
                END IF
            END IF
        NEXT
    NEXT
    FOR i = 1 TO 5
        MID$(hsdata$(i), 1, 2) = "0" + LTRIM$(STR$(i))
    NEXT
    RETURN
END SUB

SUB PSLC (y!, x, t$)
    _PRINTSTRING ((x - 1) * 8, (y! - 1) * 16), t$
END SUB

SUB PSL (y!, x, t$)
    _PRINTSTRING ((x - 1) * _FONTWIDTH, (y! - 1) * _FONTHEIGHT), t$
    Overlay_Hardware = _COPYIMAGE(Overlay, 33)
    _PUTIMAGE (0, 0), Overlay_Hardware
    _FREEIMAGE Overlay_Hardware
END SUB

SUB underline (y, x, uflag)
    STATIC ucnt
    ucnt = -ucnt - 1
    IF ucnt OR uflag THEN
        LINE ((x - 1) * _FONTWIDTH, y * _FONTHEIGHT)-((x - 1) * _FONTWIDTH + 12, y * _FONTHEIGHT), _RGB(24, 24, 24), BF
    ELSE
        LINE ((x - 1) * _FONTWIDTH, y * _FONTHEIGHT)-((x - 1) * _FONTWIDTH + 12, y * _FONTHEIGHT), Yellow, BF
    END IF

    Overlay_Hardware = _COPYIMAGE(Overlay, 33)
    _PUTIMAGE (0, 0), Overlay_Hardware
    _FREEIMAGE Overlay_Hardware
END SUB


Download sound effects files attachment in Post #13.

Pete
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RE: In the spirit of Terry's Tutorials - GUARDIAN Alien Space Ship Game - by Pete - 10-17-2022, 07:58 PM



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