dos33fsprogs/demosplash/starbase_alien_laser.s
2019-10-02 00:03:00 -04:00

97 lines
1.1 KiB
ArmAsm

; Handle alien laser
; uses laser1 slot
; should handle multiple at once?
;laser1_out: .byte $0
;laser1_start: .byte $0
;laser1_end: .byte $0
;laser1_y: .byte $0
;laser1_direction: .byte $0
;laser1_count: .byte $0
;=========================
; fire alien laser
;=========================
; which alien in X
fire_alien_laser:
lda laser1_out
bne done_fire_alien_laser
lda alien_x,X
sta COLLISION_X
lda alien_y,X
sta COLLISION_Y
; activate laser slot
inc laser1_out
; reset count
lda #0
sta laser1_count
; set y
; assume for now no crouching
lda alien_y,X
clc
adc #4
sta laser1_y
; set direction
lda alien_direction,X
sta laser1_direction
beq alien_laser_left
bne alien_laser_right
; set x
alien_laser_left:
stx LASER_TEMP
jsr calc_gun_left_collision
ldx LASER_TEMP
lda alien_x,X
sec
sbc #2
sta laser1_end
sec
sbc #10
sta laser1_start
jmp done_fire_alien_laser
alien_laser_right:
stx LASER_TEMP
jsr calc_gun_right_collision
ldx LASER_TEMP
lda alien_x,X
clc
adc #5
sta laser1_start
clc
adc #10
sta laser1_end
done_fire_alien_laser:
rts