'LANDER by Kevin Savetz
'March 22 2019

GRAPHICS 23:'GR. 7, no txt window. 159x92 
'normally y=95 for full GR.7 screen, we lose a little because text line at top

DIM F0$(16),F1$(10)
F0$="\00\00\00\00\3C\42\42\3C\42\7E\5A\81":'LEM graphic with blank spaces around
	'to make erasing old LEM easy as it moves vertically
'F1$ is workspace for the P1 thrust flame
FUEL=150:'starting fuel

A=PEEK(106)-20:'set aside RAM for players
POKE 54279,A:'PMBASE
P=A*256:'top of P/M memory
POKE 559,46:'Double line resolution P/M characters
VX=-5+RAND(11):'Initial X speed
POKE 53277,2:'turn on players (not missiles)
M=DPEEK(88):'top of screen RAM
MOVE M,P+512,384:'zero Player data, copying 0s from the fresh blank screen
POKE 704,88:'PCOLR0. I like purple.

'custom display list
D=DPEEK(741):'location of display list
POKE D+4,66:'top line is Graphics 0 text line (mode 2)
-MOVE D+102,D+99,3:'shorten the display list so screen's not too tall
POKE 752,1:'hide cursor

'draw terrain & stars/ground texture
COLOR 1
PLOT 0,90-RAND(60):'start drawing terrain on left edge
LPP=1:'first segment can't be landing pad
FOR I=10 TO 150 STEP 10
	Z=M+40+RAND(3500):'pick a location for star/ground texture
	POKE Z,PEEK(Z)!3:'draw it
	IF (LPP OR (RAND(5) OR LP=2)):'draw craggy rock if we just drew a landing pad
			'or if we've alreadt drawn 2. Otherwise, maybe draw a pad
		II=RAND(40)+52:'rock height
		COLOR 1:'color of rock
		LPP=0:'remember that last thing drawn isn't a pad
	ELSE
		COLOR 2:'color of pads
		LP=LP+1:'count number of landing pads
		LPP=1:'remember last thing drawn is a pad
	ENDIF
	DRAWTO I,II:'draw the rock/pad
NEXT I
COLOR 1
DRAWTO 159,60
PAINT 159,92

DT=.05:'Time increment. Lower numbers make the game slower
X=50+RAND(125):'Initial X
Y=520:'Initial Y
G=RAND(15)+5:'Strength of gravity
VY=1+RAND(10):'Initital Y speed

DO:'main loop
	POKE 53278,0:'Clear PM collisions
	X=X+VX*DT:'change LEM's X
	POKE P+Y+264,0:'clear side thrust
	Y=Y+VY*DT:'change LEM's Y
	VY=VY+G*DT:'new Y speed
	POKE 53248,X:'HPOSP0 position LEM at new X 
	MOVE ADR(F0$),P+Y,16:'draw LEM at new vertical position

	'clean up from last move...
	-MOVE M,P+Y+136,12:'copy 0s from top corner of screen to erase flame (if any)
	SOUND:'stop thrust sound if any

	'thrust. Player 1 is the bottom thrust flame
	IF FUEL AND STRIG(0)=0:'if trigger and have fuel
		VY=VY-2:'decrease vertical speed
		MOVE ADR(F1$),P+Y+136,10:'place flame 8 lines below P0
		SOUND 0,50+Y,8,8:'I KNOW, there's no sound in space
		POKE 53249,X:'P1 X position
		POKE 705,50+RAND(11):'flame color
		FOR Z=3 TO 8
			POKE ADR(F1$)+Z,RAND(16)*4:'rows of random flame, but only 4 bytes
								 'in the middle so it isn't too wide 00111100
		NEXT Z
		FUEL=FUEL-1:'reduce fuel
	ELSE:'if no trigger, check for left/right thrust. Player 2 is the side thrust flame
		S=STICK(0)
		Z=(S=7)-(S=11):'get joystick left-right status
		IF Z AND FUEL AND NOT FIRE:'if joystick and have fuel and LEM isn't thrusting up
			POKE P+Y+264,3:'put P2 flame at correct vertical position relative to LEM
			POKE 53250,X-3+(4*Z):'side flame on left or right of LEM
			POKE 706,50+RAND(11):'P2 color
			VX=VX-Z:'change X speed
			SOUND 0,50,8,8:'noise
			FUEL=FUEL-1
		ENDIF
	ENDIF
	
	POKE 87,0:'get ready to print in text window
	
	'If LEM goes off screen or hits terrain or hits landing pad too fast
	IF X<40 OR X>205 OR Y<510 OR PEEK(53252)&1 OR (PEEK(53252)&2 AND (VY>10 OR ABS(VX)>5))
		FOR Z=1 TO 250:'explosion
			SOUND 0,50+RAND(30),6,8:'in space no one can hear you scream
			MOVE 59740+RAND(500),P+Y+4,12:'copy random data from ROM to P1
			POKE 704,50+RAND(21):'P1 color
		NEXT Z
		RUN:'restart
	ENDIF

	'show speed, gravity, and fuel
	POS. 14,0:?"\1B\1D";INT(VY);" \1B\1F";INT(VX);
	?" \C7";G;" \C6";FUEL;"  "

	IF(PEEK(53252)&2):'touched landing pad, make happy music & restart
		SOUND 0,121,10,10:PAUSE 80
		SOUND 1,81,10,10:PAUSE 80
		SOUND 2,60,10,10:PAUSE 150
		RUN		
	ENDIF
		
LOOP