dos33fsprogs/ootw/laser.s
Vince Weaver f0b2666749 ootw: fix laser so you can shoot through shields properly
bug was noticed when developling demosplash2019
2020-01-28 16:24:32 -05:00

371 lines
4.6 KiB
ArmAsm

; FIXME: merge a lot of the target code
; Handle laser
; should handle multiple at once?
; when pressed, find empty slot?
; initially 10 wide, from gun to right or left
; expand to 20 wide
; stop when encounter door, enemy, or edge of screen
; should bounds check carefully
; should handle shooting while crouching
MAX_LASERS = 2
laser_out:
laser0_out: .byte $0
laser1_out: .byte $0
laser_start:
laser0_start: .byte $0
laser1_start: .byte $0
laser_end:
laser0_end: .byte $0
laser1_end: .byte $0
laser_y:
laser0_y: .byte $0
laser1_y: .byte $0
laser_direction:
laser0_direction: .byte $0
laser1_direction: .byte $0
laser_count:
laser0_count: .byte $0
laser1_count: .byte $0
;=========================
; fire laser
;=========================
fire_laser:
lda PHYSICIST_X
; adjust so laser pokes out from shield
ldx DIRECTION ; 0=left, 1=right
beq laser_facing_left
clc
adc #5 ; only add 5 if facing right
jmp laser_done_adjust
laser_facing_left:
sec
sbc #2 ; decrement 2 if facing left
laser_done_adjust:
sta COLLISION_X
lda PHYSICIST_Y
sta COLLISION_Y
lda laser0_out
bne done_fire_laser
; activate laser slot
inc laser0_out
; reset count
lda #0
sta laser0_count
; set y
lda PHYSICIST_Y
clc
adc #4
ldx PHYSICIST_STATE
cpx #P_CROUCH_SHOOTING
bne laser_crouch_done
laser_crouch:
clc
adc #4
laser_crouch_done:
sta laser0_y
; set direction
lda DIRECTION
sta laser0_direction
beq laser_left
bne laser_right
; set x
laser_left:
jsr calc_gun_left_collision
ldx PHYSICIST_X
dex
stx laser0_end
txa
sec
sbc #10
sta laser0_start
jmp done_fire_laser
laser_right:
jsr calc_gun_right_collision
lda PHYSICIST_X
clc
adc #5
sta laser0_start
clc
adc #10
sta laser0_end
done_fire_laser:
rts
;====================
; draw laser
;====================
draw_laser:
ldx #0
draw_laser_loop:
lda laser_out,X
beq done_draw_laser
txa
pha ; save X on stack
lda #$10
sta hlin_color_smc+1
lda #$0f
sta hlin_mask_smc+1
ldy laser_y,X
sec
lda laser_end,X
sbc laser_start,X
sta LASER_TEMP
lda laser_start,X
ldx LASER_TEMP
jsr hlin
pla ; restore X from stack
tax
done_draw_laser:
inx
cpx #MAX_LASERS
bne draw_laser_loop
rts
;===================
; move laser
;===================
move_laser:
ldx #0
move_laser_loop:
lda laser_out,X
beq done_move_laser
; slow down laser
lda laser_count,X
and #$3
bne no_move_laser
lda laser_direction,X
bne move_laser_right
move_laser_left:
lda laser_count,X
cmp #4
bcc still_starting_left
cmp #8
bcc still_shooting_left
continue_shooting_left:
still_shooting_left:
lda laser_end,X
sec
sbc #10
sta laser_end,X
still_starting_left:
lda laser_start,X
sec
sbc #10
sta laser_start,X
laser_edge_detect_left:
lda laser_end,X
cmp LEFT_SHOOT_LIMIT
bmi disable_laser_left
lda laser_start,X
cmp LEFT_SHOOT_LIMIT
bpl no_move_laser
lda LEFT_SHOOT_LIMIT
sta laser_start,X
jmp no_move_laser
move_laser_right:
lda laser_count,X
cmp #4
bcc still_starting_right
cmp #8
bcc still_shooting_right
continue_shooting_right:
lda laser_start,X
clc
adc #10
sta laser_start,X
still_shooting_right:
lda laser_end,X
clc
adc #10
sta laser_end,X
still_starting_right:
laser_edge_detect_right:
; detect if totally off screen
lda laser_start,X
cmp RIGHT_SHOOT_LIMIT
bcs disable_laser_right
lda laser_end,X
cmp RIGHT_SHOOT_LIMIT
bcc no_move_laser
lda RIGHT_SHOOT_LIMIT
sta laser_end,X
no_move_laser:
inc laser_count,X
done_move_laser:
inx
cpx #MAX_LASERS
bne move_laser_loop
rts
;===================
; hit something, left
;===================
disable_laser_left:
lda LEFT_SHOOT_TARGET
jmp hit_something_common
;====================
; hit something, right
;====================
disable_laser_right:
lda RIGHT_SHOOT_TARGET
;======================
; hit something, common
;======================
hit_something_common:
pha
; disable laser
lda #0
sta laser_out,X
pla
tay
and #$f0
cmp #TARGET_ALIEN
beq laser_hit_alien
cmp #TARGET_FRIEND
beq laser_hit_friend
cmp #TARGET_PHYSICIST
beq laser_hit_physicist
; FIXME: reduce shields if hit them?
jmp done_hit_something
laser_hit_alien:
tya
and #$f
tay
lda #A_DISINTEGRATING
sta alien_state,Y
lda #0
sta alien_gait,Y
jmp done_hit_something
laser_hit_friend:
lda #F_DISINTEGRATING
sta friend_state
lda #FAI_DISINTEGRATING
sta friend_ai_state
lda #0
sta friend_gait
jmp done_hit_something
laser_hit_physicist:
lda #P_DISINTEGRATING
sta PHYSICIST_STATE
lda #0
sta GAIT
done_hit_something:
jmp done_move_laser
; rts