I'd like to share the last two "games" I've done with ZxBC.
They are extremely simple because I've done them upon request from my sons and they are 4 years old.
The first one is called Ciclopes (y Saturno). It's a pong/football twist played by two cyclops (well, they are merely balls with one eye but apparently that's how cyclops looks like for a Little boy) and the ball is the planet Saturn. Keys are QAZX and PLNM.
The second one is Coches. It's a simple super sprint twist for two players. Keys are QAZX and PLNM, but to make thing easier the key Y toggle between the manual and the automatic mode. In the automatic mode you just have to accelerate and brake and the car turns by itself when it finds an obstacle.
With the key H you toggle between the different curses and with the key G you change the color of the cars.
I usually make these games (and the crap games for the CSSCGC compo) to try different things to use if I ever make a non crap game. And in this two games there is a thing I'm proud of: My very first assembler routine. It's a symple sprite XORing routine but with a little trick: When moving the sprites, instead of just erasing the full sprite (XORing it) in the previous location and then printing it in the new coordinates, it does this but one byte after other. The result is that I can get rid of the sprite flashing at the cost of a little tearing, and this is a sacrifice I accept happily because before I wasted too much time re-ordering the sprites (to print first the ones that were higher in the screen) or making dumb cycles waiting for the screen retrace.
I hope you like them.
P.S. If anyone is interested in the code, I warn you it's completely rubbish (untidy, un-commented...).
Actually, they are sort of cool. You should definitely put them on WOS. Nice job! Very smooth cars, there
I'm very much pro source code being posted - but for small games like this, it's especially important, if you don't mind other people looking - we want more people to learn zxbc.
Later I'll upload the files needed to do the compilation (the binaries for the curse maps, and the sprite routine once I have made comments in it too):
Code:
'-T -B -S 32768 -a %F.bas
#include <sinclair.bas>
#include <keys.bas>
'THESE VARIABLES DOESN'T REFRESH AFTER A RESTART, THAT' WHY THEY ARE DEFINED BEFORE THE GAME START.
DIM PANTALLA, COLORCOCHES,AUTOMATICO AS UBYTE
LET PANTALLA=0 'INITIAL SCREEN NUMBER
LET COLORCOCHES=2 'INITIAL CARS COLOR
LET AUTOMATICO=0 'TOGGLE AUTOMATIC MODE ON/OFF (0>OFF, OTHER>ON)
'THIS IS WHERE THE GAME JUMPS AFTER A RESET
PRINCIPIODELTODO:
IF PANTALLA>5 THEN LET PANTALLA=0: END IF 'IF YOU INSERT A NEW CURSE, DON'T FORGET TO INCREASE THE MAX NUMBER OF SCREENS (5 HERE)
IF COLORCOCHES>7 THEN LET COLORCOCHES=1: END IF 'WHEN SELECTED A COLOR>7, CYCLE
PAPER 0: BORDER 5: INK 3: BRIGHT 0: CLS
'DRAW THE CURSE
DIM POSICION,A,B,PINTA,COLORES AS UINTEGER
POKE @ATTRCIRCUITOS,(64+COLORCOCHES) 'THIS SETS THE CAR COLOUR. IN FACT, WE POKE THE COLOUR OF THE FIRST TILE (THE ROAD) WITH THE INK CODE
FOR A=0 TO 22
FOR B=0 TO 31
LET POSICION=(A*32)+B
LET PINTA=PEEK (@CIRCUITOUNO + POSICION+(736*PANTALLA))
POKE UINTEGER 23675,(@GFXCIRCUITOS+PINTA*8) 'TO DRAW THE SCREEN, WE POINT THE UDG VARIABLE WITH THE PERTINENT TILE AND THEN
PRINT AT A,B;CHR (144) 'WE PRINT IT
'PRINT AT A,B;PINTA
LET COLORES=PEEK (PINTA+@ATTRCIRCUITOS) 'SAME THING WITH COLOURS
setattr (A,B,COLORES)
NEXT
NEXT
IF AUTOMATICO THEN PRINT AT 23,5;PAPER 7;INK 2;"A";AT 23,26;PAPER 7;INK 2;"A": END IF '"A" MEANS WE HAVE SELECTED AUTOMATIC MODE
DIM X,Y,XA,YA,FRAME,FRAMEA,DIRECCION,DIRECCIONA,LIMUNO,LIMDOS,LIMTRES,LIMCUATRO,LIMCINCO,LIMSEIS,LIMSIETE,LIMOCHO,LIMNUEVE AS UINTEGER
DIM XS,YS,XSA,YSA,FRAMES,FRAMESA,DIRECCIONS,DIRECCIONSA,LIMSUNO,LIMSDOS,LIMSTRES,LIMSCUATRO,LIMSCINCO,LIMSSEIS,LIMSSIETE,LIMSOCHO,LIMSNUEVE AS UINTEGER
DIM IZDA,DCHA,ABAJ,ARRI,N,S,W,E,VEL AS UBYTE
DIM IZDAS,DCHAS,ABAJS,ARRIS,NS,SS,WS,ES,VELS AS UBYTE
DIM VECTORX (0 TO 7) AS BYTE => {-1,-1,0,1,1,1,0,-1} 'VECTORX> MEANS THE DISPLACEMENT IN THE X COORDINATE FOR EACH OF THE DIRECTIONS (N,NE,E,SE,S,SW,W,NW)
DIM VECTORY (0 TO 7) AS BYTE => {0,1,1,1,0,-1,-1,-1} 'VECTORY> MEANS THE DISPLACEMENT IN THE Y COORDINATE FOR EACH OF THE DIRECTIONS (N,NE,E,SE,S,SW,W,NW)
LET X=5: LET Y=72: LET XA=5: LET YA=72 'X AND Y> COORDINATES // XA AND YA> PREVIOUS COORDINATES (TO ERASE THE SPRITE OR GO BACK)
LET FRAME=Y MOD 8: LET FRAMEA=YA MOD 8 'FRAMEY> RELATIVE POSITION OF THE SPRITE IN A 8 PIXEL BOUNDARY. WE NEED THIS BECAUSE WE USE PRE-ROTATED GRAPHICS
LET DIRECCION=2: LET DIRECCIONA=2 'DIRECCION=DIRECTION WE ARE FACING
LET VEL=0 'VEL=SPEED. WE MULTIPLY THIS NUMBER WITH THE PERTINENT VECTORX/VECTORY TO CALCULATE THE DISPLACEMENT.
LET XS=19: LET YS=72: LET XSA=19: LET YSA=72 'SAME AS BEFORE, BUT FOR PLAYER 2
LET FRAMES=YS MOD 8: LET FRAMESA=YSA MOD 8
LET DIRECCIONS=2: LET DIRECCIONSA=2
LET VELS=0
'CALLING THE SPRITE ROUTINE IN THE FORM (X,Y,GRAPHIC,XA,YA,PREVIOUSGRAPHIC)
xorsprite (X,Y,@COCHE+(FRAME*48)+(DIRECCION*384),XA,YA,@vacio) 'AS THIS IS THE FIRST PRINT, WE CHOOSE AN EMPTY BUFFER (vacio) AS PREVIOUS GRAPHIC
xorsprite (XS,YS,@COCHEDOS+(FRAMES*48)+(DIRECCIONS*384),XSA,YSA,@vacio) 'SAME FOR PLAYER 2
'HERE STARTS THE MAIN LOOP
BUCLEPRINCIPAL:
'READING KEYS FOR PLAYER ONE
LET IZDA=MULTIKEYS(KEYZ): IF IZDA THEN LET W=3: END IF
LET DCHA=MULTIKEYS(KEYX): IF DCHA THEN LET E=2: END IF
LET ABAJ=MULTIKEYS(KEYA): IF ABAJ THEN LET S=1: END IF
LET ARRI=MULTIKEYS(KEYQ): IF ARRI THEN LET N=0: END IF
'READING KEYS FOR PLAYER TWO
LET IZDAS=MULTIKEYS(KEYN): IF IZDAS THEN LET WS=3: END IF
LET DCHAS=MULTIKEYS(KEYM): IF DCHAS THEN LET ES=2: END IF
LET ABAJS=MULTIKEYS(KEYL): IF ABAJS THEN LET SS=1: END IF
LET ARRIS=MULTIKEYS(KEYP): IF ARRIS THEN LET NS=0: END IF
'LEFT AND RIGHT ROTATE THE DIRECCION
IF IZDA THEN LET DIRECCION=DIRECCION-1: END IF
IF DCHA THEN LET DIRECCION=DIRECCION+1: END IF
'UP AND DOWN ACCELERATE OR BRAKE
IF ABAJ AND VEL>0 THEN LET VEL=VEL-1: GOSUB VELOCIMETRO: END IF
IF ARRI AND VEL<8 THEN LET VEL=VEL+1: GOSUB VELOCIMETRO: END IF 'MAX SPEED=8 PIXEL (THIS CAN BE ALTERED)
'SAME AS BEFORE FOR PLAYER 2
IF IZDAS THEN LET DIRECCIONS=DIRECCIONS-1: END IF
IF DCHAS THEN LET DIRECCIONS=DIRECCIONS+1: END IF
IF ABAJS AND VELS>0 THEN LET VELS=VELS-1: GOSUB VELOCIMETRO: END IF
IF ARRIS AND VELS<8 THEN LET VELS=VELS+1: GOSUB VELOCIMETRO: END IF
'READING SPECIAL KEYS //H=NEXT CURSE //G=ALTER COLOUR //Y=TOGGLE AUTOMATIC ON/OFF
IF MULTIKEYS(KEYH) THEN LET PANTALLA=PANTALLA+1: GOTO PRINCIPIODELTODO: END IF
IF MULTIKEYS(KEYG) THEN LET COLORCOCHES=COLORCOCHES+1: GOTO PRINCIPIODELTODO: END IF
IF MULTIKEYS(KEYY) THEN LET AUTOMATICO=AUTOMATICO XOR 1: GOTO PRINCIPIODELTODO: END IF
IF DIRECCION>250 THEN LET DIRECCION=7: END IF 'WE DON'T WANT DIRECTION TO BE<0. AS THE VARIABLE IS UNSIGNED, WHEN IT'S BELLOW 0 ITS IN FACT 255
IF DIRECCION>7 THEN LET DIRECCION=0: END IF 'IF DIRECTION<7 CYCLE IT
IF DIRECCIONS>250 THEN LET DIRECCIONS=7: END IF 'SAME FOR PLAYER 2
IF DIRECCIONS>7 THEN LET DIRECCIONS=0: END IF
'HERE WE RECALCULATE THE X AND Y COORDINATES BY MULTIPLY THE SPEED WITH THE PERTINENT DISPLACEMENT IN THE VECTOR MATRIX
LET X=X+(VECTORX(DIRECCION)*VEL)
LET Y=Y+(VECTORY(DIRECCION)*VEL)
'SAME FOR PLAYER 2
LET XS=XS+(VECTORX(DIRECCIONS)*VELS)
LET YS=YS+(VECTORY(DIRECCIONS)*VELS)
IF AUTOMATICO=0 THEN GOTO SALTOAUTOMATICOUNO: END IF 'IF AUTOMATIC MODE IS OFF, WE DON'T WANT THE CAR TO STEER WHEN IT FINDS AND OBSTACLE
'DECREASE SPEED AND TURN THE CAR WHEN THE CAR IS IN THE SCREEN BOUNDS
IF X>166 OR X<1 THEN LET X=XA: LET Y=YA: LET VEL=VEL-1: LET DIRECCION=DIRECCION+1: GOSUB VELOCIMETRO: END IF
IF Y>237 OR Y<1 THEN LET Y=YA: LET X=XA: LET VEL=VEL-1: LET DIRECCION=DIRECCION+1: GOSUB VELOCIMETRO: END IF
IF XS>166 OR XS<1 THEN LET XS=XSA: LET YS=YSA: LET VELS=VELS-1: LET DIRECCIONS=DIRECCIONS+1: GOSUB VELOCIMETRO: END IF
IF YS>237 OR YS<1 THEN LET YS=YSA: LET XS=XSA: LET VELS=VELS-1: LET DIRECCIONS=DIRECCIONS+1: GOSUB VELOCIMETRO: END IF
IF AUTOMATICO THEN GOTO SALTODOS: END IF 'IS AUTOMATIC MODE IS SET, WE HAVE ALREADY CHECKED THE BOUNDS, SO WE SKIP THE NEXT INSTRUCTIONS
SALTOAUTOMATICOUNO:
'DECRESE SPEED WHEN THE CAR IS IN THE SCREEN BOUNDS
IF X>166 OR X<1 THEN LET X=XA: LET Y=YA: LET VEL=VEL-1: GOSUB VELOCIMETRO: END IF
IF Y>237 OR Y<1 THEN LET Y=YA: LET X=XA: LET VEL=VEL-1: GOSUB VELOCIMETRO: END IF
IF XS>166 OR XS<1 THEN LET XS=XSA: LET YS=YSA: LET VELS=VELS-1: GOSUB VELOCIMETRO: END IF
IF YS>237 OR YS<1 THEN LET YS=YSA: LET XS=XSA: LET VELS=VELS-1: GOSUB VELOCIMETRO: END IF
SALTODOS:
GOSUB LIMITES 'JUMP TO DO THE COLISION DETECTION
'CALCULATE THE 8 PIXEL BOUNDARIES
LET FRAME=Y MOD 8
LET FRAMES=YS MOD 8
PAUSE 1 'WE DON'T REALLY NEED TO DO THIS, BUT THE TIMMING IS BETTER IF WE DO
xorsprite (X,Y,@COCHE+(FRAME*48)+(DIRECCION*384),XA,YA,@COCHE+(FRAMEA*48)+(DIRECCIONA*384))
xorsprite (XS,YS,@COCHEDOS+(FRAMES*48)+(DIRECCIONS*384),XSA,YSA,@COCHEDOS+(FRAMESA*48)+(DIRECCIONSA*384))
'HERE WE UPDATE THE "PREVIOUS" VALORS WITH THE "CURRENT" VALORS AND GO BACK TO THE BEGGINING OF THE LOOP
LET XA=X: LET YA=Y: LET FRAMEA=FRAME: LET DIRECCIONA=DIRECCION
LET N=0: LET S=0: LET E=0: LET W=0
LET XSA=XS: LET YSA=YS: LET FRAMESA=FRAMES: LET DIRECCIONSA=DIRECCIONS
LET NS=0: LET SS=0: LET ES=0: LET WS=0
GOTO BUCLEPRINCIPAL
STOP
'SPEEDMETER PRINTING (IN THE BOTTOM OF THE SCREEN)
VELOCIMETRO:
IF VEL>16 THEN LET VEL=0: END IF
PRINT AT 23,0;PAPER 6;" "
PRINT AT 23,0;PAPER 6;VEL*30;" "
IF VELS>16 THEN LET VESL=0: END IF
PRINT AT 23,28;PAPER 6;" "
PRINT AT 23,28;PAPER 6;VELS*30;" "
RETURN
'COLISION DETECTION, ATTRIBUTE BASED. WE COLLIDE WITH ANYTHING NOT BRIGHT. AS THE SPRITES ARE 16X16 PIXEL BUT PRE-ROTATED, WE HAVE IN FACT 24X16 SPRITES
'BUT GIVEN THAT WE PLACE THE SPRITES IN HIGH RESOLUTION (VERTICALY) WE HAVE TO CHECK FOR AN ADITIONAL CHARACTER LINE
'SO WE DO CHECK 9 CHARACTER BOXES (3,3 AND 3)
LIMITES:
LET LIMUNO=attr (INT(X/8),INT(Y/8)): LET LIMDOS=attr (INT(X/8),INT(Y/8)+1): LET LIMTRES=attr (INT(X/8),INT(Y/8)+2): LET LIMCUATRO=attr (INT(X/8)+1,INT(Y/8)):LET LIMCINCO=attr (INT(X/8)+1,INT(Y/8)+1): LET LIMSEIS=attr (INT(X/8)+1,INT(Y/8)+2): LET LIMSIETE=attr (INT(X/8)+2,INT(Y/8)): LET LIMOCHO=attr (INT(X/8)+2,INT(Y/8)+1): LIMNUEVE=attr (INT(X/8)+2,INT(Y/8)+2)
LET LIMSUNO=attr (INT(XS/8),INT(YS/8)): LET LIMSDOS=attr (INT(XS/8),INT(YS/8)+1): LET LIMSTRES=attr (INT(XS/8),INT(YS/8)+2): LET LIMSCUATRO=attr (INT(XS/8)+1,INT(YS/8)):LET LIMSCINCO=attr (INT(XS/8)+1,INT(YS/8)+1): LET LIMSSEIS=attr (INT(XS/8)+1,INT(YS/8)+2): LET LIMSSIETE=attr (INT(XS/8)+2,INT(YS/8)): LET LIMSOCHO=attr (INT(XS/8)+2,INT(YS/8)+1): LIMSNUEVE=attr (INT(XS/8)+2,INT(YS/8)+2)
IF AUTOMATICO=0 THEN GOTO SALTOAUTOMATICODOS: END IF 'IF NOT AUTOMATIC, WE SKIP NEXT INSTRUCTIONS (CARS STEERING ALONE)
'IF COLLISION, DECREASE SPEED AND ALTER (RANDOM, I COULD'T BE BOTHERED WITH A WAYPOINT SYSTEM) THE DIRECTION
IF (LIMUNO)<64 OR (LIMDOS)<64 OR (LIMTRES)<64 OR (LIMCUATRO)<64 OR (LIMCINCO)<64 OR (LIMSEIS)<64 OR (LIMSIETE)<64 OR (LIMOCHO)<64 OR (LIMNUEVE)<64 THEN LET X=XA: LET Y=YA: LET VEL=VEL-1: LET DIRECCION=DIRECCION+(INT(RND*3)-1): GOSUB VELOCIMETRO: END IF
IF (LIMSUNO)<64 OR (LIMSDOS)<64 OR (LIMSTRES)<64 OR (LIMSCUATRO)<64 OR (LIMSCINCO)<64 OR (LIMSSEIS)<64 OR (LIMSSIETE)<64 OR (LIMSOCHO)<64 OR (LIMSNUEVE)<64 THEN LET XS=XSA: LET YS=YSA: LET VELS=VELS-1: LET DIRECCIONS=DIRECCIONS+(INT(RND*3)-1): GOSUB VELOCIMETRO: END IF
SALTOAUTOMATICODOS:
IF AUTOMATICO THEN RETURN: END IF 'IF AUTOMATIC, WE ARE DONE.
'IF COLLISION, DECREASE SPEED
IF (LIMUNO)<64 OR (LIMDOS)<64 OR (LIMTRES)<64 OR (LIMCUATRO)<64 OR (LIMCINCO)<64 OR (LIMSEIS)<64 OR (LIMSIETE)<64 OR (LIMOCHO)<64 OR (LIMNUEVE)<64 THEN LET X=XA: LET Y=YA: LET VEL=VEL-1: GOSUB VELOCIMETRO: END IF
IF (LIMSUNO)<64 OR (LIMSDOS)<64 OR (LIMSTRES)<64 OR (LIMSCUATRO)<64 OR (LIMSCINCO)<64 OR (LIMSSEIS)<64 OR (LIMSSIETE)<64 OR (LIMSOCHO)<64 OR (LIMSNUEVE)<64 THEN LET XS=XSA: LET YS=YSA: LET VELS=VELS-1: GOSUB VELOCIMETRO: END IF
RETURN
#include "sprite3.bas"
vacio: 'EMPTY BUFFER (FOR THE FIRST TIME WE PRINT THE SPRITES)
ASM
vacio:
DEFB 0,0,0,0,0,0,0,0
DEFB 0,0,0,0,0,0,0,0
DEFB 0,0,0,0,0,0,0,0
DEFB 0,0,0,0,0,0,0,0
DEFB 0,0,0,0,0,0,0,0
DEFB 0,0,0,0,0,0,0,0
END ASM
COCHE: 'CAR ONE GRAPHICS. N,NE,E,SE,S,SW,W,NW
ASM
; ASM source file created by SevenuP v1.20
; SevenuP (C) Copyright 2002-2006 by Jaime Tejedor Gomez, aka Metalbrain
;GRAPHIC DATA:
;Pixel Size: ( 24, 16)
;Char Size: ( 3, 2)
;Frames: 8
;Sort Priorities: X char, Char line, Y char, Frame number
;Data Outputted: Gfx
;Interleave: Sprite
;Mask: No
The map binaries. They are made with Mappy using the .png included in the zipped archive.
If anyone want to create a new track, don't forget to include as a binary at the end of the code (incibin "circuitoequis.map) and increase the max number of tracks at the beggining of the code
Here goes the sprite routine. You have to name it sprite3.bas (or change the incluide statement in the main program listing)
Code:
'XOR SPRITE SUBROUTINE. HERE WE JUST POKE THE COORDINATES IN THE FORM (X COORD,Y COORD,GFX ADDRESS,PREVIOUS X COORD, PREVIOUS Y COORD, PREVIOUS GFX ADDRESS)
SUB xorsprite (xd as ubyte,yd as ubyte, gfx as uinteger, xda as ubyte, yda as ubyte, gfxa as uinteger)
POKE @esprite,xd: POKE @esprite+1,yd: POKE Uinteger (@esprite+2),gfx
POKE @esprite+4,xda: POKE @esprite+5,yda: POKE Uinteger (@esprite+6),gfxa
gosub printsprite
END SUB
'SUBROUTINE TO SELECT THE HEIGHT OF THE SPRITE (TO SKIP SOME CYCLES IF WE DON'T NEED TO PRINT 16 LINES)
SUB spriteh (h as ubyte)
POKE @altura+1,h-1
END SUB
'MEMORY LOCATIONS WHERE WE KEEP THE COORDINATES AND THE GRAPHICS ADDRESSES
esprite:
ASM
xp: defb 0
yp: defb 0
gfxdir: defw 0
xpa: defb 0
ypa: defb 0
gfxant: defw 0
END ASM
'XORing ROUTINE. IT'S A VERY SIMPLE AND STRIGHTFORWARD ROUTINE WITH NO OPTIMIZATION, BUT I'M VERY HAPPY WITH THE RESULT BEING IT MY FIRST ATTEMP AT M/C
'IT MAKES USE OF TWO ROUTINES: SCADD TO CALCULATE THE SCREEN ADDRESS GIVEN THE X AND Y COORDINATES. THIS IS BORROWED FROM J.CAULDWELL'S "HOW TO WRITE
'ZX SPECTRUM GAMES" TUTORIAL. AND UPHL, A LITTLE ROUTINE TO CALCULATE THE SCREEN ADDRESS OF THE LINE BELLOW THE CURRENT ADDRESS. I HAVE CHANGED IT FOR
'CONVENIENCE TO UPDE. I CAN'T REMEMBER WHERE I TOOK IT FROM, PROBABLY SOME POST IN WOS.
'HOW THE ROUTINE WORKS IS EASY. WE NEED THE SPRITE ADDRESS IN HL AND THE SCREEN ADDRESS IN DE (WE PUT THE CORRDINATES IN BC AND CALL THE SCADD ROUTINE THAT
'RETURNS THE ADRESS IN DE)
'THEN WE SWAP REGISTERS AND MAKE THE SAME OPERATION WITH THE PREVIOUS SPRITE ADRRESS AND THE PREVIOUS COORDINATES.
'FROM NOW ON IT'S VERY EASY, WE JUST CLEAR (XOR) THE CONTENT OF THE PREVIOUS SCREEN POSITION, SWAP REGISTERS AND THEN PRINT THE NEW SPRITE BYTE IN THE NEW
'ADDRESS. WE DO THIS 3 TIMES (AS THE SPRITES ARE IN FACT 3 CHARACTERS WIDE, BECAUSE THEY ARE 16 PIXEL WIDE BUT PRESHIFTED TO THE RIGHT 8 TIMES)
'NOW WE CALL DE UPDE ROUTINE, DECREASE DE AND HL IN 3 (SO WE ARE IN THE CORRECT COLUMN) AND THEN REPEAT IT 15 TIMES MORE.
printsprite:
ASM
sprite:
ld hl,(gfxdir)
ld bc,(xp)
call scadd ; calculate screen address.
exx
ld hl,(gfxant)
ld bc,(xpa)
call scadd ;ahora tenemos en los dos sets de registros alternativos(actual y anterior): direccion del grafico en hl, dirección de pantalla en de
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a
exx
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a ;pintamos el primer byte, primero el anterior (alternativo) y luego el actual
inc hl
inc de
exx
inc hl
inc de
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a
exx
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a ;pintamos el segundo byte
inc hl
inc de
exx
inc hl
inc de
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a
exx
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a ;pintamos el tercer byte
END ASM
altura:
ASM
ld b,15
repeticiones:
dec de
dec de
call upde
inc hl
exx
dec de
dec de
call upde
inc hl
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a
exx
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a ;pintamos el primer byte, primero el anterior (alternativo) y luego el actual
inc hl
inc de
exx
inc hl
inc de
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a
exx
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a ;pintamos el segundo byte
inc hl
inc de
exx
inc hl
inc de
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a
exx
ld a,(de)
ld c,a
ld a,(hl)
xor c
ld (de),a ;pintamos el tercer byte
djnz repeticiones
END ASM
ASM
; This routine returns a screen address for (c, b) in de.
scadd: ld a,c ; get vertical position.
and 7 ; line 0-7 within character square.
add a,64 ; 64 * 256 = 16384 (Start of screen display)
ld d,a ; line * 256.
ld a,c ; get vertical again.
rrca ; multiply by 32.
rrca
rrca
and 24 ; high byte of segment displacement.
add a,d ; add to existing screen high byte.
ld d,a ; that's the high byte sorted.
ld a,c ; 8 character squares per segment.
rlca ; 8 pixels per cell, mulplied by 4 = 32.
rlca ; cell x 32 gives position within segment.
and 224 ; make sure it's a multiple of 32.
ld e,a ; vertical coordinate calculation done.
ld a,b ; y coordinate.
rrca ; only need to divide by 8.
rrca
rrca
and 31 ; squares 0 - 31 across screen.
add a,e ; add to total so far.
ld e,a ; hl = address of screen.
ret
;uphl:
; inc h
; ld a,h
; and 7
; ret nz
; ld a,l
; add a,32
; ld l,a
; ret c
; ld a,h
; sub 8
; ld h,a
; ret
upde:
inc d
ld a,d
and 7
ret nz
ld a,e
add a,32
ld e,a
ret c
ld a,d
sub 8
ld d,a
ret
END ASM
If you look at the code for this routine or the main program you will see that I'll never become another Peter Moligneux. But if you check my earlier posts in this fórum you'll probably get to the conclussion that it's posible with ZxBC to transit from zero knowledge in programming to a point where you can do some cool things and get a lot of fun trying. That's what I love about this compiler, it makes things possbile.
If anyone need any further explanation, just ask here and I'll see if I can help.
P.S. Later in the day I'll try to post the code for the cyclops game. Or better still, instead of posting the code as is I'll do a Little tweak to show just the bouncing saturn and a moving cyclop for better readability.
As promised here goes the tweaked version of the cyclops game.
I decided to go with this "demo" versión because the code of the original game is very similar to the one in the cars, so the interest in it should be even lower
On top of that, this version lets me show the true purpose of the sprite routine behind these games: Act as a simple but easy to use routine that lets the novice programmer (a.k.a. "me") concentrate in other aspects of the game.
In this version there is no gameplay, but you can move the "cyclops" witn the keys QAZX and PLNM. You'll see this time 4 bouncing saturns in the screen. Pressing the Y key changes the number of saturns from 1 to 8. Given that each planet is composed by 2 sprites (the planet itself and its shadow) it can make a total of 18 sprites in the screen moving simultaneously. Obviously the speed is very compromised when reaching a high number of sprites but my goal is to show that is feasible to have a reasonable number of moving sprites controlled from basic without caring for the annoying flashing.
The code (incluides at least one routine from our personal best Zx Basic Programmer Britlion):
Code:
REM CYCLOP'S SATURN BOUNCING PONGOLFSKET DELUXE EDITION SPECIAL VMAX FUSSBALL MASTER
#include <sinclair.bas>
#include <keys.bas>
DIM MAXSATURNOS AS UBYTE
LET MAXSATURNOS=3
INICIODELTODO:
IF MAXSATURNOS>7 THEN LET MAXSATURNOS=0: END IF
PAPER 6: BORDER 5:INK 0: CLS
FOR A=0 TO 9: PRINT AT A,0;PAPER 5;INK 0;" ": NEXT A
PRINT AT 1,13;PAPER 6;INK 0;" ";AT 2,13;PAPER 6;INK 0;" "
PRINT AT 1,17;PAPER 6;INK 0;" ";AT 2,17;PAPER 6;INK 0;" "
PRINT AT 8,3;PAPER 6;INK 0;" "
PRINT AT 7,3;PAPER 6;INK 0;" "
PLOT 0,0: DRAW 255,0:DRAW 0,112: DRAW -255,0: DRAW 0,-112
PLOT 0,30: DRAW 30,0: DRAW 0,52: DRAW -30,0
PLOT 255,30: DRAW -30,0: DRAW 0,52: DRAW 30,0
PLOT 128,0: DRAW 0,112
CIRCLE 128,56,20
PAPER 6
PLOT 108,136: DRAW 0,31:DRAW -10,0: DRAW 0,17: DRAW 28,0: DRAW 0,-17: DRAW -12,0: DRAW 0,-31
PLOT 140,136: DRAW 0,31:DRAW -10,0: DRAW 0,17: DRAW 28,0: DRAW 0,-17: DRAW -12,0: DRAW 0,-31
PLOT 0,112: DRAW 30,24:DRAW 195,0: DRAW 30,-24
PAPER 5
'CIRCLE 220,170,8: CIRCLE 217,172,2: CIRCLE 223,172,2: PLOT 216,167: DRAW 8,0,2
'PLOT 10,160: DRAW 8,-4,2: DRAW 12,5,3: DRAW 9,3,4: DRAW 1,8,3: DRAW -10,2,3: DRAW -8,-1,3: DRAW -10,-2,4: DRAW -2,-10,3
DIM GOLUNO, GOLDOS AS UBYTE
doubleSizePrintChar(1,13,48+MAXSATURNOS+1)
DIM X,Y,XA,YA,FRAMEX,FRAMEY,FRAMEXA,FRAMEYA AS UINTEGER
DIM XD,YD,XDA,YDA,FRAMEXD,FRAMEYD,FRAMEXDA,FRAMEYDA AS UINTEGER
DIM XS,YS,XSA,YSA,FRAMESY,FRAMESYA AS UINTEGER
DIM ALTURA,ALTURAA,VHG AS UBYTE
DIM VELSX,VELSY AS BYTE
DIM REBOTE AS INTEGER
LET GOLUNO=0: LET GOLDOS=0
LET X=80:LET Y=0: LET XA=80: LET YA=0
LET FRAMEX=(INT(X) MOD 8): LET FRAMEXA=(INT (XA) MOD 8)
IF FRAMEX THEN LET FRAMEX=8-FRAMEX: END IF
IF FRAMEXA THEN LET FRAMEXA=8-FRAMEXA: END IF
LET FRAMEY=INT(Y) MOD 8: LET FRAMEYA=INT (YA) MOD 8
LET XD=176:LET YD=240: LET XDA=176: LET YDA=240
LET FRAMEXD=(INT(XD) MOD 8): LET FRAMEXDA=(INT (XDA) MOD 8)
IF FRAMEXD THEN LET FRAMEXD=8-FRAMEXD: END IF
IF FRAMEXDA THEN LET FRAMEXDA=8-FRAMEXDA: END IF
LET FRAMEYD=INT(YD) MOD 8: LET FRAMEYDA=INT (YDA) MOD 8
LET XS=132:LET YS=121: LET XSA=132: LET YSA=121
LET FRAMESY=INT(YS) MOD 8: LET FRAMESYA=INT(YSA) MOD 8
LET ALTURA=10: LET ALTURAA=10: LET REBOTE=30: LET VHG=10
LET VELSX=0: LET VELSY=0
DIM SATURNOXY (0 TO 7,0 TO 7) AS INTEGER => {{132,121,132,121,10,10,30,10},_ 'X,Y,XA,YA,ALTURA,ALTURAA,REBOTE,REBOTENEG
{132,20,132,20,10,10,30,10},_
{132,170,132,170,10,10,30,10},_
{132,40,132,40,10,10,30,10},_
{132,60,132,60,10,10,30,10},_
{132,80,132,80,10,10,30,10},_
{132,100,132,100,10,10,30,10},_
{132,150,132,150,10,10,30,10}}
FOR N=0 TO MAXSATURNOS
LET FRAMESY=SATURNOXY(N,1) MOD 8
spriteh (6)
xorsprite (SATURNOXY(N,0),SATURNOXY(N,1),@SOMBRA+(FRAMESY*48),SATURNOXY(N,2),SATURNOXY(N,3),@vacio)
spriteh (10)
xorsprite (SATURNOXY(N,0)-SATURNOXY(N,4),SATURNOXY(N,1),@SATURNO+(FRAMESY*48),SATURNOXY(N,2)-SATURNOXY(N,5),SATURNOXY(N,3),@vacio)
NEXT
SALTOUNO:
BUCLEPPAL:
IF MULTIKEYS(KEYX) AND Y<240 THEN LET Y=Y+1: END IF
IF MULTIKEYS(KEYZ) AND Y>0 THEN LET Y=Y-1: END IF
IF MULTIKEYS(KEYA) AND X<176 THEN LET X=X+1: END IF
IF MULTIKEYS(KEYQ) AND X>64 THEN LET X=X-1: END IF
IF MULTIKEYS(KEYM) AND YD<240 THEN LET YD=YD+1: END IF
IF MULTIKEYS(KEYN) AND YD>0 THEN LET YD=YD-1: END IF
IF MULTIKEYS(KEYL) AND XD<176 THEN LET XD=XD+1: END IF
IF MULTIKEYS(KEYP) AND XD>64 THEN LET XD=XD-1: END IF
IF MULTIKEYS(KEYY) THEN LET MAXSATURNOS=MAXSATURNOS+1: GOTO INICIODELTODO: END IF
LET XS=XS+VELSX: IF (XS>185 OR XS<80) THEN LET XS=XSA: LET VELSX=VELSX*-1: END IF
LET YS=YS+VELSY: IF (YS>240 OR YS<1) THEN LET YS=YSA: LET VELSY=VELSY*-1: GOSUB GOL: END IF
LET FRAMEY=INT(Y) MOD 8: LET FRAMEYA=INT (YA) MOD 8
LET FRAMEX=(INT(X) MOD 8): LET FRAMEXA=(INT (XA) MOD 8)
IF FRAMEX THEN LET FRAMEX=8-FRAMEX: END IF
IF FRAMEXA THEN LET FRAMEXA=8-FRAMEXA: END IF
LET FRAMEYD=INT(YD) MOD 8: LET FRAMEYDA=INT (YDA) MOD 8
LET FRAMEXD=(INT(XD) MOD 8): LET FRAMEXDA=(INT (XDA) MOD 8)
IF FRAMEXD THEN LET FRAMEXD=8-FRAMEXD: END IF
IF FRAMEXDA THEN LET FRAMEXDA=8-FRAMEXDA: END IF
'LET REBOTE=REBOTE-INT(REBOTE/VHG)
'LET ALTURA=ALTURA+INT(REBOTE/VHG)-1: IF ALTURA<6 THEN LET REBOTE=40: GOSUB FRENAZO: END IF 'REBOTE=11 PARADO LET VELSX=0: LET VELSY=0
'LET FRAMESY=INT(YS) MOD 8: LET FRAMESYA=INT(YSA) MOD 8
'IF ALTURA<14 AND (X-XS)>65526 AND ((Y-YS)-4)>65528 THEN GOSUB CHOQUEUNO: END IF
'IF ALTURA<14 AND (XD-XS)>65526 AND ((YD-YS)-4)>65528 THEN GOSUB CHOQUEDOS: END IF
FOR N=0 TO MAXSATURNOS
LET SATURNOXY(N,6)=SATURNOXY(N,6)-INT (SATURNOXY(N,6)/SATURNOXY(N,7))
LET SATURNOXY(N,4)=SATURNOXY(N,4)+INT (SATURNOXY(N,6)/SATURNOXY(N,7))-1: IF SATURNOXY(N,4)<6 THEN LET SATURNOXY(N,6)=40+INT(RND*80): GOSUB FRENAZO: END IF
LET FRAMESY=SATURNOXY(N,1) MOD 8
LET FRAMESYA=SATURNOXY(N,3) MOD 8
spriteh (6)
xorsprite (SATURNOXY(N,0),SATURNOXY(N,1),@SOMBRA+(FRAMESY*48),SATURNOXY(N,2),SATURNOXY(N,3),@SOMBRA+(FRAMESYA*48))
spriteh (10)
xorsprite (SATURNOXY(N,0)-SATURNOXY(N,4),SATURNOXY(N,1),@SATURNO+(FRAMESY*48),SATURNOXY(N,2)-SATURNOXY(N,5),SATURNOXY(N,3),@SATURNO+(FRAMESYA*48))
NEXT
SALTODOS:
LET YA=Y: LET XA=X
LET YDA=YD: LET XDA=XD
LET XSA=XS: LET YSA=YS: LET ALTURAA=ALTURA
FOR N=0 TO 7
LET SATURNOXY(N,2)=SATURNOXY(N,0): LET SATURNOXY(N,3)=SATURNOXY(N,1): LET SATURNOXY(N,5)=SATURNOXY(N,4)
NEXT
GOTO BUCLEPPAL
STOP
CHOQUEUNO:
LET VELSX=65531-(X-XS)
LET VELSY=65532-((Y-YS)-4)
LET REBOTE=(ABS(VELSX)+ABS(VELSY))*25: IF REBOTE<40 THEN LET REBOTE=40: END IF
RETURN
CHOQUEDOS:
LET VELSX=65531-(XD-XS)
LET VELSY=65532-((YD-YS)-4)
LET REBOTE=(ABS(VELSX)+ABS(VELSY))*25: IF REBOTE<40 THEN LET REBOTE=40: END IF
RETURN
FRENAZO:
IF VELSX THEN LET VELSX=(ABS(VELSX)-0.5)*(ABS(VELSX)/VELSX): END IF
IF VELSY THEN LET VELSY=(ABS(VELSY)-0.8)*(ABS(VELSY)/VELSY): END IF
RETURN
GOL:
IF ALTURA<40 AND XS<155 AND XS>110 THEN GOSUB GOLAZO: END IF
RETURN
GOLAZO:
IF YS<16 THEN LET GOLUNO=GOLUNO+1: END IF
IF YS>230 THEN LET GOLDOS=GOLDOS+1: END IF
IF GOLUNO>9 THEN GOTO PLGANA: END IF
IF GOLDOS>9 THEN GOTO PLGANA: END IF
doubleSizePrintChar(1,13,48+GOLDOS)
doubleSizePrintChar(1,17,48+GOLUNO)
RETURN
BUFFERATTRSATURNO:
ASM
DEFB 0,0,0,0,0,0
END ASM
BUFFERATTRCICLOPEUNO:
ASM
DEFB 0,0,0,0,0,0
END ASM
BUFFERATTRCICLOPEDOS:
ASM
DEFB 0,0,0,0,0,0
END ASM
STOP
SUB doubleSizePrintChar(y AS UBYTE, x AS UBYTE, thingToPrint AS UBYTE)
' Prints a single character double sized.
' Takes X and Y values as character positions, like print.
' takes an ascii code value for a character.
' By Britlion, 2012.
ASM
LD A,(IX+5) ;' Y value
CP 22
JP NC, doubleSizePrintCharEnd
;' A=y value
LD E,A
AND 24 ; calculate
OR 64 ; screen
LD H,A ; address
LD A,E ; FOR
AND 7 ; row
OR a ; Y
RRA
RRA
RRA
RRA
LD E,A
LD A,(IX+7) ;' X Value
CP 30
JP NC, doubleSizePrintCharEnd
ADD A,E ;' correct address for column value. (add it in)
LD L,A
EX DE,HL ;' Save it in DE
LD A,(IX+9) ;'Character
CP 164 ;' > UDG "U" ?
JP NC, doubleSizePrintCharEnd
CP 32 ;' < space+1?
JP C, doubleSizePrintCharEnd
CP 144 ;' >144?
JP NC, doubleSizePrintCharUDGAddress
LD L,A
LD H,0
ADD HL,HL
ADD HL,HL
ADD HL,HL ;' multiply by 8.
LD BC,(23606) ;' Chars
ADD HL,BC ;' Hl -> Character data.
EX DE,HL ;' DE -> character data, HL-> screen address.
JP doubleSizePrintCharRotateLoopCharStart
doubleSizePrintCharUDGAddress:
LD HL,(23675) ;'UDG address
SUB 144
ADD A,A ;multiply by 8.
ADD A,A
ADD A,A
ADD A,L
LD L,A
JR NC, doubleSizePrintCharUDGAddressNoCarry
INC H
doubleSizePrintCharUDGAddressNoCarry:
;' At this point HL -> Character data in UDG block.
EX DE,HL ;' DE -> character data, HL-> screen address.
doubleSizePrintCharRotateLoopCharStart:
LD C,2 ;' 2 character rows.
doubleSizePrintCharRotateLoopCharRowLoopOuter:
LD b,4 ;' 4 source bytes to count through per character row.
doubleSizePrintCharRotateLoopCharRowLoopInner:
PUSH BC
LD A,(DE) ;' Grab a bitmap.
PUSH DE
LD B,4
doubleSizePrintCharRotateLoop1:
RRA
PUSH AF
RR E
POP AF
RR E
DJNZ doubleSizePrintCharRotateLoop1
LD B,4
doubleSizePrintCharRotateLoop2:
RRA
PUSH AF
RR D
POP AF
RR D
DJNZ doubleSizePrintCharRotateLoop2
LD (HL),D ;' Output first byte
INC HL ;' Move right
LD (HL),E ;' Second half.
DEC HL ;' Move left
INC H ;' Move down
LD (HL),D ;' Output second row (copy of first), first byte.
P.S. There's one thing I wanted to write about the graphics. The sprite routine is the same for both games, but if you check the code in the cars game there are fewer graphics. That's because in the car's game we change the picture in every horizontal displacement (the graphics are pre-shifted) and in the cyclops game we also change the picture in every vertical displacement. That's a lot more memory usage but the "rolling" effect is nice
