To make an explosion with a collision, a simple FOR/NEXT loop is created to check the coordinates of each space ship. If they intersect, the program call the sub "explosion." The explosion sub consists of a particle burst, flashing screen, produced with a palette loop, and thunder sounds, which require downloading and unzipping the attached zip containing the .ogg sound file.
Stage 5)
In the next update the aliens will be given a bit more A.I. to avoid colliding with one another.
Pete
Stage 5)
Code: (Select All)
DIM SHARED top, bottom, left, right, s_delay
a = 120: b = 42
WIDTH a, b
_SCREENMOVE 0, 0
top = 3: bottom = _HEIGHT: left = 0: right = _WIDTH
msg$ = "Alien space ship movement demo."
LOCATE 1, (right - left) \ 2 - LEN(msg$) \ 2
PRINT msg$;
LOCATE 1, 2: PRINT STRING$(_WIDTH, "_");
VIEW PRINT top TO bottom ' Needed to set print error parameters.
s_delay = 100
DO
_LIMIT 30
IF _KEYDOWN(100306) THEN IF s_delay - 5 > 0 THEN s_delay = s_delay - 5: LOCATE 1, 2: PRINT "Speed delay ="; s_delay / 100; " ";
IF _KEYDOWN(100308) THEN IF s_delay < 500 THEN s_delay = s_delay + 5: LOCATE 1, 2: PRINT "Speed delay ="; s_delay / 100; " ";
IF LEN(INKEY$) THEN SOUND 1000, .1
alien_move
LOOP
offscreen:
IF ERR = 5 THEN er = -1: RESUME NEXT
PRINT "Opps, you have an error"; ERR
END
SUB alien_move:
STATIC alien$, a_y(5), a_x(5), olda_y(5), olda_x(5), inertia(5), ran(5), ran_y(5), ran_x(5), oldran(5), z5, z6, itr, alien_ship_max
IF alien$ = "" THEN
alien$ = "-<>-": alien_ship_max = 5 ' Initiate.
CALL explosion ' Loads sound files on first call.
END IF
IF ABS(z5 - TIMER) > s_delay / 1000 THEN ' Time delay.
DO
itr = itr + 1: IF itr > alien_ship_max THEN itr = 1 ' Needed to offset the EXIT DO hover event, which on exit does not affect the itr variable.
y_restore = CSRLIN: x_restore = POS(0) ' Restore column and row upon exit.
IF olda_y(itr) <> 0 AND olda_x(itr) <> 0 THEN LOCATE olda_y(itr), olda_x(itr): PRINT SPACE$(LEN(alien$));
IF inertia(itr) = 0 THEN
inertia(itr) = INT(RND * (bottom - top) / 2) + 1 ' How many moves to go in any one direction.
ran(itr) = INT(RND * 8) + 1 ' Choose 1 of 8 possible directions.
IF ran(itr) = oldran(itr) OR olda_y(itr) = 0 AND olda_x(itr) = 0 AND ran = 1 OR olda_y(itr) = 0 AND olda_x(itr) = 0 AND ran = 5 THEN
EXIT DO ' 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 ran(itr) ' Get changes in column and row coordinates.
CASE 1: ran_y(itr) = -1: ran_x(itr) = 0 ' Up.
CASE 2: ran_y(itr) = -1: ran_x(itr) = 1 ' Up and right.
CASE 3: ran_y(itr) = 0: ran_x(itr) = 1 ' Right.
CASE 4: ran_y(itr) = 1: ran_x(itr) = 1 ' Down and right.
CASE 5: ran_y(itr) = 1: ran_x(itr) = 0 ' Down.
CASE 6: ran_y(itr) = 1: ran_x(itr) = -1 ' Down and left.
CASE 7: ran_y(itr) = 0: ran_x(itr) = -1 ' Left.
CASE 8: ran_y(itr) = -1: ran_x(itr) = -1 ' Up and left.
END SELECT
IF olda_y(itr) = 0 AND olda_x(itr) = 0 THEN ' New alien space ship enters the screen.
a_y(itr) = (bottom - top) \ 2: a_x(itr) = (right - left) \ 2 ' Center sreen.
a_y(itr) = (bottom - top) \ 4 + RND * (bottom - top) \ 4
IF ran(itr) < 5 THEN ' Determine side of entry from initial direction.
a_x(itr) = left + 1 ' Enter from the left side and go right.
ELSE
a_x(itr) = right - LEN(alien$) ' Enter from the right side and go left.
END IF
END IF
oldran(itr) = ran(itr) ' Remember last direction. Another line uses this to disallow any RND that chooses the same direction twice.
ELSE
inertia(itr) = inertia(itr) - 1 ' Count down the number of moves in any one direction. When zero, switch direction.
END IF
a_y(itr) = a_y(itr) + ran_y(itr): a_x(itr) = a_x(itr) + ran_x(itr) * 2 ' Next move coordinates. I use * 2 for horizontal movement to match the 16x8 pixel height over width factor.
IF a_y(itr) < top OR a_y(itr) > bottom OR a_x(itr) <= left OR a_x(itr) + LEN(alien$) > right THEN
olda_x(itr) = 0: olda_y(itr) = 0: inertia(itr) = 0: oldran(itr) = 0 ' Out of bounds and off the screen.
ELSE
LOCATE a_y(itr), a_x(itr): PRINT alien$; ' Move alien space ship.
' Check for collisions.
FOR i = 1 TO alien_ship_max
IF i <> itr AND a_y(i) <> 0 THEN
IF a_y(itr) = a_y(i) AND a_x(itr) >= a_x(i) AND a_x(itr) < a_x(i) + LEN(alien$) THEN
LOCATE a_y(i), a_x(i): PRINT SPACE$(LEN(alien$));: LOCATE a_y(itr), a_x(itr): PRINT SPACE$(LEN(alien$));
CALL explosion
a_y(irt) = 0: a_x(i) = 0 ' Remove exploded alien space ships.
END IF
END IF
NEXT
olda_y(itr) = a_y(itr): olda_x(itr) = a_x(itr) ' Remember these coordinates to erase alien space ship on next loop.
END IF
IF itr = alien_ship_max THEN itr = 0: EXIT DO
IF ABS(z6 - TIMER) > s_delay / 2 THEN skipz5 = -1: EXIT DO
LOOP
IF skipz5 = 0 THEN z5 = TIMER
z6 = TIMER
LOCATE y_restore, x_restore ' Restore entry column and row positions.
END IF
END SUB
SUB explosion
STATIC sound_check, soundfile%, t1&, t6&, t7&, t8&
IF sound_check = 0 THEN
IF _FILEEXISTS("Thunder1.ogg") AND _FILEEXISTS("Thunder1.ogg") AND _FILEEXISTS("Thunder1.ogg") AND _FILEEXISTS("Thunder1.ogg") THEN soundfile% = -1
IF soundfile% THEN
t1& = _SNDOPEN("Thunder1.ogg", "SYNC")
t6& = _SNDOPEN("Thunder6.ogg", "SYNC")
t7& = _SNDOPEN("Thunder7.ogg", "SYNC")
t8& = _SNDOPEN("Thunder8.ogg", "SYNC")
END IF
sound_check = -1
EXIT SUB
END IF
b_y1 = CSRLIN: b_x1 = POS(0)
h = 0
ON ERROR GOTO offscreen
DO
IF h = 1 THEN burst$ = " " ELSE burst$ = CHR$(249)
h = h + 1
GOSUB flash
FOR i = 1 TO 5
SELECT CASE i
CASE 1
COLOR 15
LOCATE b_y1, b_x1: PRINT burst$;
_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
ON ERROR GOTO 0
COLOR 7
EXIT SUB
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 t1&
_DELAY .05
PALETTE 0, 0
_SNDPLAY t7&
ELSE
_DELAY .075
END IF
eflag = -1
z7 = TIMER
END IF
PALETTE 0, 0
RETURN
END SUBIn the next update the aliens will be given a bit more A.I. to avoid colliding with one another.
Pete