Interplay's Learn to Program Basic (Review Copy)/Learn to Program Basic Review Copy (Interplay)(June 23, 1998).ISO/pc/ltpbasic/projects/ufobombr.bas

BASIC Source File | 1998-03-26 | 6.5 KB | 343 lines

Rem UFO Bomber!
Rem By Richard

Rem Variable Setup
atkang = 3.1415926 / 4.0
oldatk = atkang
xbase = 0
ybase = 240
atklngth = 30
score = 0
numallowed = 1
numbullets = 0
maxbullets = 3
bulletspd = 10
ufohere = 0
ufospeed = 0
ufodir = 0
ufox = 0
ufoy = 0
bombon = 0
bombx = 0
bomby = 0
bombyp = 0
ufohit = 0
endx = cos(atkang)*atklngth + xbase
endy = ybase - sin(atkang)*atklngth

Rem Set a maximum speed (in frames per second)
fps = 25
loopSpeed = 1000/fps

Rem Intstructions
Cls
Print "- UFO Bomber -"
Print
Print "Your goal is to stop bombardment"
Print "of Planet Earth.  Use the keys A and Z"
Print "keys to aim your weapon, and the space"
Print "bar to fire.  Good luck!"
Print
Input "<Press the Enter or Return key to go on>",a$
Cls

Rem Load in the sprites
ufospr = LoadSprite("ufo")
HideSprite ufospr
expspr = LoadSprite("Woozy01")
HideSprite expspr
SetSprite expspr range 4 to 10
bombspr = LoadSprite("Woozy01")
SetSprite bombspr range 0 to 3
HideSprite bombspr
hits = 0


Rem Set up our arrays, and set up the bullets
Dim bulleton(maxbullets)
Dim bulletspr(maxbullets)
Dim bulletx(maxbullets)
Dim bullety(maxbullets)
Dim bulletxp(maxbullets)
Dim bulletyp(maxbullets)
for t = 1 to maxbullets
bulletspr(t) = LoadSprite("bullet")
bulleton(t) = 0
next t

Rem Screen Setup
Cls
Background "earth"
SetDrawLayer(TEXT)
Gosub UpdateCannon

Rem Main Loop!
Rem Wait for keypresses, while updating the UFO, its bomb,
Rem and flying bullets.
while 1
lastTick = Timer()
Gosub UpdateUFO
Gosub UpdateBullets
if bombon then Gosub UpdateBomb

Rem Handle keypresses for aiming the cannon
if keydown("A") then
atkang = atkang + .1
if atkang > 1.54 then atkang = 1.54
Gosub UpdateCannon
Goto SkipRest
Endif
if keydown("z") then
atkang = atkang - .1
if atkang < .1 then atkang = .1
Gosub UpdateCannon
Goto SkipRest
endif

SkipRest:
Rem Fire cannon?
if keydown("space") then Gosub FireCannon

Rem Limit overall execution speed to reasonable maximum
while Timer()-lastTick < loopSpeed
wend

wend
end

Rem If the user moves the turret, play a little sound and redraw it on the screen.
Rem Note that the cannon uses geometry COSINE and SINE calculations to draw a line
Rem pointing outwards at an arbritrary angle.

UpdateCannon:
Sound "tank2"

Rem Erase Old cannon line
Rem Since we're using the text layer, we can use a -1 color to erase
Color -1
Line xbase,ybase+1 to endx,endy+1
Line xbase,ybase to endx,endy

Rem Draw New cannon line
Color 5 'Uh..Black?
endx = cos(atkang)*atklngth + xbase
endy = ybase - sin(atkang)*atklngth
Line xbase,ybase+1 to endx,endy+1
Line xbase,ybase to endx,endy
return

Rem This routine fires a bullet
Rem We use COSINE and SINE again to send the bullet out across the screen at a
Rem certain angle.  We do a lot of pre-calculation on the bullet, so that
Rem the bullet update routine (which is executed very often ) has to do as
Rem little as possible.

FireCannon:
if numbullets >= numallowed then return
numbullets = numbullets + 1
for t = 1 to maxbullets
if bulleton(t)=0 then
Sound "biggun1"
bulletx(t) = endx
bullety(t) = endy
bulletxp(t) = cos(atkang)*bulletspd
bulletyp(t) = -sin(atkang)*bulletspd
SetSprite bulletspr(t) to bulletxp(t),bulletyp(t)
ShowSprite bulletspr(t)
CycleSprite bulletspr(t)
bulleton(t) = 1
t = maxbullets
endif
next t
return

Rem Update bullets
UpdateBullets:
for t = 1 to maxbullets
if bulleton(t) then
bulletx(t) = bulletx(t) + bulletxp(t)
bullety(t) = bullety(t) + bulletyp(t)
Rem Simulate a little gravity on the bullet
bulletyp(t) = bulletyp(t) + .1
Rem Is bullet still valid?
if bulletx(t) > 320 or bullety(t) < 0 then
bulleton(t) = 0
HideSprite bulletspr(t)
numbullets = numbullets - 1
else
SetSprite bulletspr(t) to bulletx(t),bullety(t)

Rem Now check for a collision with a bomb sprite
if bombon then
if SpriteHitSprite(bombspr,bulletspr(t)) then
score = score + (bombyp * 200)
Sound "boing1"
bombon = 0
HideSprite bombspr
numbullets = numbullets - 1
HideSprite bulletSpr(t)
bulleton(t) = 0
endif
endif
Rem if theres a ufo on the screen, check to see if we hit it and if so,
Rem destroy it.
if ufohere and ufohit = 0 then
if SpriteHitSprite(ufospr,bulletspr(t)) then
score = score + (ufospd * 20)
Sound "exp_big"
HideSprite bulletspr(t)
bulleton(t) = 0
numbullets = numbullets - 1

Rem Upgrade players capabilities
hits = hits + 1
if hits = 10 then
bulletspd = 14
endif
if hits = 15 then
numallowed = 2
bulletspd = 16
endif
if hits = 20 then
bulletspd = 18
endif
if hits = 25 then
numallowed = 3
endif

ufohit = 25
HideSprite ufospr
SetSprite expspr to ufox,ufoy
CycleSprite expspr
endif
endif
endif
endif
next t
return

Rem Update ufo sprite
UpdateUFO:
if ufohere = 0 then
if random(1,1000) > 25 then
return
else
Sound "whizby"
ufohere = 1
TextColor -1
ufox = 0
ufoy = random(20,160)
ufospd = random(2,4) + (hits / 5)
CycleSprite ufospr
endif
else
if ufohit then
ufohit = ufohit - 1
if ufohit = 0 then
ufohere = 0
HideSprite expspr
endif
return
endif
endif

ufox = ufox + ufospd
if ufox > 320 then
HideSprite ufospr
ufohere = 0
endif

SetSprite ufospr to ufox,ufoy

if bombon = 0 and random(1,100) = 2 then
if ufoy < 130 then
if ufox > 20 and ufox < 300 then
bombon = 1
bombx = ufox + 20
bomby = ufoy
bombyp = (hits / 8) + random(2,4)
endif
endif
endif

return

Rem Update the UFO's bomb
UpdateBomb:

bomby = bomby + bombyp
SetSprite bombspr to bombx,bomby
if bomby > 230 then Goto GameOver
return

Rem this is the end...
Rem A variety of techniques are being used in this
Rem "Game Over" scene.  One thing to notice is that
Rem the 'x' position of the astronaut is also driving
Rem other events.  Also, 'snd' is used as a counter
Rem to trigger a sound effect every tenth iteration of the
Rem loop.  Learning these methods can help you create
Rem interesting scenes where a variety of things are
Rem happening at once.

GameOver:
cls
HideSprite ufospr
HideSprite expspr
for t = 1 to maxbullets
HideSprite bulletspr(t)
next t

Background "earth"
astro = LoadSprite("astro")
x = -40
TextColor 6

snd = 0
while x < 350
x =x + 1
SetSprite astro to x,80
Rem part 1 ... a beam of devastation from above
if x > 80 and x < 100 then

if snd > 10 then
snd = 0
sound "lazer1"
else
snd = snd + 1
endif

diff = x - 80
if diff > 11 then diff = 11
color 6 + x
line 160 - diff, 1 to 160 - diff,240
line 160 + diff, 1 to 160 + diff,240
endif

Rem part 2 ... effect of said beam
if x > 100 then

if snd > 10 then
snd = 0
sound "exp_far"
else
snd = snd + 1
endif

diff = x - 100
xcircle = random(1,320)
ycircle = 240 - (diff*2)
color random(6,21)
FillCircle xcircle,ycircle,40-diff
endif
wend
Color 21
FillRect 0,0 to 320,240
DrawText "@RED,HELVETICA,BOLD,50@Game Over" AT 25,10
Banner "The Earth Is Toast"
End