Os alienígenas seguem um padrão de movimento que é uma combinação de movimentos direcionais, Direção 0-15, cada uma representando um ponto de uma bússola de 16 pontos, e um número de repetições.
Os padrões são guardados numa tabela DATA no fim do evento. Cada linha da tabela de dados representa um padrão próprio do nível a que o jogador chegou.
No jogo de demonstração, os alienígenas de uma vaga de ataque são removidos quando o jogador lhes dispara ou quando saem do ecrã, mas podes alterá-lo facilmente para outros estilos de jogo.
O número de alienígenas de uma vaga de ataque e outros parâmetros são definidos em separado no evento Spawner.
Está incluído um sprite de alienígena predefinido na imagem de sprite 2; tem 16 fotogramas, cada um correspondente a um valor de direção, o que facilita garantir que é mostrado o fotograma correto consoante a direção de deslocação atual do alienígena.
Os alienígenas também podem disparar mísseis ao jogador. Como e quando o fazem é totalmente personalizável e baseia-se nas definições feitas no evento Spawner para cada vaga de ataque específica, por isso podes definir a que altura do ecrã têm de estar antes de disparar, a sua probabilidade de disparo e a que distância à esquerda e à direita do jogador é permitido um possível lançamento de míssil.
EVENT SPRITETYPE5 ;======= ENEMIES ============ ;==================================== ; ; VARIABLES ; ======================================================= ; DIRECTION - CURRENT DIRECTION OF TRAVEL,( 254= OUT OF BOUNDS, 255= EXPLODE) ; SETTINGA - STATUS (0= INITIALISE, 1=GET DIRECTION & REPS, 2=MOVE) ; SETTINGB - # REPETITIONS OF CURRENT DIRECTION ; AIRBORNE - CHANCE OF FIRING WEAPON (0 = NO, 1 = YES) ; JUMPSPEED - availabe for use in your game ; ======================================================== SPRITEINK C ; colour the alien with C value IF SETTINGA = 0 ; Alien first appears RESTORE ; Restore the data table LET RND = L ; Store the Level number in RND ADD 50 TO RND ; and increase it by 50 WHILE DIRECTION <> RND ; While DIRECTION doesnt = RND READ DIRECTION ; Read value from DATA table READ SETTINGB ; Also read second value ENDWHILE ; Keep going until we find the value in RND LET SETTINGA = 1 ; When we find it change SA to 1 ENDIF IF SETTINGA = 1 ; ready to get direction & reptitions READ DIRECTION ; read the next movement into DIRECTION READ SETTINGB ; read the repetitions into SettingB LET SETTINGA = 2 ; ready to do the movement IF IMAGE 2 ; is this image 2? LET FRAME = DIRECTION ; yes, set the frame to the same as direction ENDIF ENDIF ; COLLISIONS ; ============================== IF COLLISION 1 ; if hit by a player torpedo OTHER ; switch to torpedo LET DIRECTION = 99 ; run the explosion ENDSPRITE ; return to this Alien LET DIRECTION = 255 ; request alien explosion ENDIF IF COLLISION 0 ; if enemy and player collide OTHER ; switch to the player LET DIRECTION = 99 ; trigger the player explosion ENDSPRITE ; return to this sprite LET DIRECTION = 255 ; request alien explosion ENDIF ; EXPLODE THE ALIEN ; ======================= IF DIRECTION = 255 ; Alien explosion requested LET TYPE = 6 ; switch it to the explosion type LET IMAGE = 4 ; and the explosion image LET FRAME = 0 ; reset it to first frame LET DIRECTION = 0 ; this is an alen exploding ENDIF ; MOVEMENT ; ==================== IF DIRECTION = 0 ; Move N SPRITEUP SPRITEUP ENDIF IF DIRECTION = 1 ; Move NNE SPRITERIGHT SPRITEUP SPRITEUP ENDIF IF DIRECTION = 2 ; Move NE SPRITERIGHT SPRITERIGHT SPRITEUP SPRITEUP ENDIF IF DIRECTION = 3 ; Move ENE SPRITERIGHT SPRITERIGHT SPRITEUP ENDIF IF DIRECTION = 4 ; Move E SPRITERIGHT SPRITERIGHT ENDIF IF DIRECTION = 5 ; Move ESE SPRITERIGHT SPRITERIGHT SPRITEDOWN ENDIF IF DIRECTION = 6 ; MOVE SE SPRITERIGHT SPRITERIGHT SPRITEDOWN SPRITEDOWN ENDIF IF DIRECTION = 7 ; MOVE SSE SPRITEDOWN SPRITEDOWN SPRITERIGHT ENDIF IF DIRECTION = 8 ; MOVE S SPRITEDOWN SPRITEDOWN ENDIF IF DIRECTION = 9 ; MOVE SSW SPRITEDOWN SPRITEDOWN SPRITELEFT ENDIF IF DIRECTION = 10 ; MOVE SW SPRITEDOWN SPRITEDOWN SPRITELEFT SPRITELEFT ENDIF IF DIRECTION = 11 ; MOVE WSW SPRITEDOWN SPRITELEFT SPRITELEFT ENDIF IF DIRECTION = 12 ; MOVE W SPRITELEFT SPRITELEFT ENDIF IF DIRECTION = 13 ; MOVE WNW SPRITELEFT SPRITELEFT SPRITEUP ENDIF IF DIRECTION = 14 ; MOVE NW SPRITELEFT SPRITELEFT SPRITEUP SPRITEUP ENDIF IF DIRECTION = 15 ; MOVE NNW SPRITELEFT SPRITEUP SPRITEUP ENDIF ; BOUNDARY CHECKING ; =================== IF X <= LEFTEDGE ; if alien reaches the left edge LET DIRECTION = 254 ; enemy is out of bounds ENDIF IF X >= RIGHTEDGE ; if alien reaches the right edge LET DIRECTION = 254 ; enemy is out of bounds ENDIF IF Y >= BOTTOMEDGE ; if alien reaches the right edge LET DIRECTION = 254 ; enemy is out of bounds ENDIF IF DIRECTION =254 ; is enemy out of bounds? REMOVE ; remove it SUBTRACT 1 FROM S ; decrement the sprite counter SUBTRACT 1 FROM F ; decrement the alien counter ENDIF ; CHECK IF ALIEN CAN RELEASE WEAPON ; ================================= IF Y < Q ; is alien above minimum height for releasing missiles? IF W > 0 ; yes, can alien release missiles? IF X < M ; yes, is Alien to the right of player? SUBTRACT X FROM M ; yes, how far to the right of player? IF M <= I ; I or less pixels? LET AIRBORNE = 1 ; run the chance of firing routine ENDIF ADD X TO M ; reset M ELSE IF M < X ; is alien to the left of player? SUBTRACT M FROM X ; yes, how far to the left IF X < = I ; I pixels or less? LET AIRBORNE = 1; yes, run the chance of firing routine ENDIF ADD M TO X ; reset X ELSE ; enemy must be directly above player LET AIRBORNE = 1 ; run the chance of firing routine ENDIF ENDIF ENDIF ENDIF ; CHANCE OF FIRING ; ==================== IF AIRBORNE = 1 ; Chance of firing routine IF S < 9 ; are there 8 or less sprites on screen? GETRANDOM H ; yes, get a random number from 0 to the aliens missile probability # IF RND = 1 ; is it 1? LET RND = DIRECTION ; yes, store aliens direction in RND SPAWN 3 6 ; spawn a missile SPAWNED ; switch to the spawned missile LET DIRECTION = RND ; set its direction to RND ENDSPRITE ; switch back to this alien ENDIF ENDIF LET AIRBORNE = 0 ; end the chance of firing routine ENDIF ; REPETITIONS CHECK ; ====================== SUBTRACT 1 FROM SETTINGB ; decrement repetitions remaining IF SETTINGB = 0 ; has alien moved all repetitions? LET SETTINGA = 1 ; get the next direction & # of repetitions ENDIF ; MOVEMENT PATTERNS ; ======================== DATA 51 0 8 20 7 8 6 8 5 8 4 16 DATA 52 0 8 20 9 8 10 8 11 8 12 16 DATA 53 0 12 48 11 2 10 2 9 2 8 2 7 2 6 2 5 2 4 40 5 2 6 2 7 2 8 2 9 2 10 40 DATA 54 0 4 48 5 2 6 2 7 2 8 2 9 2 10 2 11 2 12 40 11 2 10 2 9 2 8 2 7 2 6 40 DATA 55 0 13 26 14 4 15 4 0 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 4 10 40 DATA 56 0 3 26 1 4 0 4 15 4 14 4 13 4 12 4 11 4 10 4 9 4 8 4 7 4 6 40 DATA 57 0 8 16 7 4 6 4 5 4 4 4 3 4 2 4 1 4 0 4 15 4 14 4 13 4 12 4 11 4 10 4 9 4 8 4 7 4 6 4 5 4 4 60 DATA 58 0 8 16 9 4 10 4 11 4 12 4 13 4 14 4 15 4 0 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 4 10 4 11 2 12 60 DATA 59 0 8 16 9 4 10 4 11 4 12 4 13 4 14 4 15 4 0 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 4 10 4 11 2 12 60 DATA 60 0 4 20 13 4 14 4 15 4 0 8 1 4 2 4 3 4 4 4 8 8 7 2 6 2 5 2 4 40 DATA 61 0 5 2 6 2 7 2 8 2 9 2 10 2 11 2 12 2 11 3 10 3 9 3 8 3 7 3 6 3 5 4 6 4 7 4 8 4 9 4 10 4 DATA 62 0 8 3 4 16 9 24 4 40
DATA 59 0 8 16 9 4 10 4 11 4 12 4 13 4 14 4 15 4 0 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 4 10 4 11 2 12 60
DATA 60 0 4 20 13 4 14 4 15 4 0 8 1 4 2 4 3 4 4 4 8 8 7 2 6 2 5 2 4 40
DATA 61 0 5 2 6 2 7 2 8 2 9 2 10 2 11 2 12 2 11 3 10 3 9 3 8 3 7 3 6 3 5 4 6 4 7 4 8 4 9 4 10 4
DATA 62 0 8 3 4 16 9 24 4 40