fire beam documentation
This commit is contained in:
Michael Miceli
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9df883fc3a
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352e6ff15c
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@ -1070,15 +1070,23 @@ Bombs dropped from the Alien Carrier
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Other Names: Energy Beam
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These 4 enemy types are very similar. They differ in the direction they fire
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These 3 enemy types are very similar. They differ in the direction they fire
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* #$10 - down
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* #$11 - left
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* #$12 - right
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Horizontal fire beams have randomness baked into the duration after receding to
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then re-ignite. They do not wait for player proximity either compared to the
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vertical fire beams.
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#### Attributes
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* `.... ..xx` - beam length code (0-3) (index, not actual amount)
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* `.... xx..` - beam delay between bursts (index into
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`fire_beam_anim_delay_tbl`)
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* 00 = #$00
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* 01 = #$20
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* 10 = #$40
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* 11 = #$60
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* `xx.. ....` - collision code logic, see `collision_code_f`, offset into
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`collision_code_f_adj_tbl` (0, 4, 8, or 16)
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@ -7147,12 +7147,15 @@ fire_beam_down_routine_ptr_tbl:
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.addr fire_beam_down_routine_02 ; CPU address $aa0f
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.addr fire_beam_down_routine_03 ; CPU address $aa2b
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; fire beam down - pointer 1
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; fire beam down - pointer 1 - initialize enemy and initial attack delay, then advance routine
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fire_beam_down_routine_00:
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lda #$04 ; a = #$04
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sta ENEMY_FRAME,x ; set enemy animation frame number
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lda #$80 ; a = #$80
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; set fire beam collision attribute bit, position, and initial attack/animation delay, and advance routine
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; input
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; * a - value to merge with fire beam's attributes to update collision code
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fire_beam_add_pos_set_delay:
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ora ENEMY_ATTRIBUTES,x ; merge flip bits with original enemy attributes
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sta ENEMY_ATTRIBUTES,x ; update enemy attributes (to support flipping horizontally and/or vertically)
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@ -7162,7 +7165,7 @@ fire_beam_add_pos_set_delay:
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lsr
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lsr
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and #$03 ; keep bits .... ..xx
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tay
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tay ; set ... xx.. from enemy attributes to y
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lda fire_beam_anim_delay_tbl,y ; load animation delay
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sta ENEMY_VAR_A,x ; storey in ENEMY_VAR_A
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@ -7173,13 +7176,14 @@ fire_beam_set_delay_adv_routine:
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fire_beam_anim_delay_tbl:
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.byte $00,$20,$40,$60
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; fire beam down - pointer 2
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; fire beam down - pointer 2 - wait for initial attack delay, then wait for player proximity, then initialize attack and advance routine
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fire_beam_down_routine_01:
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jsr animate_small_flame ; animate small flame when fire beam isn't firing
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jsr add_scroll_to_enemy_pos ; add scrolling to enemy position
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lda ENEMY_ANIMATION_DELAY,x ; load enemy animation frame delay counter
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bne fire_beam_dec_delay_exit ; decrement animation delay and exit if delay hasn't elapsed
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jsr player_enemy_x_dist ; a = closest x distance to enemy from players, y = closest player (#$00 or #$01)
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jsr player_enemy_x_dist ; animation delay timer elapsed, get closest player and his distance
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; a = closest x distance to enemy from players, y = closest player (#$00 or #$01)
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cmp #$20 ; see if player is within #$20 pixels of fire beam
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bcs fire_beam_down_exit ; branch if closest player is farther than #$20
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@ -7187,8 +7191,8 @@ fire_beam_down_routine_01:
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begin_fire_beam_attack:
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lda ENEMY_X_POS,x ; load enemy x position on screen
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cmp #$30 ; position at which fire beam stops firing (as player scrolls right)
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bcc fire_beam_down_exit ; don't fire if too far to the left
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lda #$09 ; a = #$09 (sound_09)
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bcc fire_beam_down_exit ; don't fire if fire beam is too far to the left
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lda #$09 ; load a = #$09 (sound_09)
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jsr play_sound ; play fire beam burning sound
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jsr enable_enemy_player_collision_check ; enable player collision check with flame
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lda ENEMY_ATTRIBUTES,x ; load enemy attributes
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@ -7204,7 +7208,7 @@ begin_fire_beam_attack:
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sta ENEMY_VAR_1,x
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sta ENEMY_VAR_3,x
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sta ENEMY_VAR_4,x
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beq fire_beam_set_delay_adv_routine
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beq fire_beam_set_delay_adv_routine ; always branch
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fire_beam_dec_delay_exit:
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dec ENEMY_ANIMATION_DELAY,x ; decrement enemy animation frame delay counter
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@ -7214,7 +7218,7 @@ fire_beam_dec_delay_exit:
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fire_beam_length_tbl:
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.byte $05,$09,$0d,$0f
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; fire beam down - pointer 3
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; fire beam down - pointer 3 - attack
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fire_beam_down_routine_02:
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jsr add_scroll_to_enemy_pos ; add scrolling to enemy position
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ldy #$00 ; y = #$00
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@ -7233,7 +7237,7 @@ set_fire_beam_delay_10_adv_routine:
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lda #$10 ; a = #$10 (delay for fire beam to stay at max)
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bne fire_beam_set_delay_adv_routine
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; fire beam down - pointer 4
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; fire beam down - pointer 4 - recede after delay, set new attack delay and go back to fire_beam_right_routine_01
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fire_beam_down_routine_03:
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jsr add_scroll_to_enemy_pos ; add scrolling to enemy position
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ldy #$02 ; y = #$02
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@ -7244,8 +7248,9 @@ fire_beam_down_routine_03:
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sta ENEMY_VAR_4,x
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bpl fire_beam_down_exit
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; set next ignition delay, disable collision, and set routine to fire_beam_xx_routine_01 to wait for delay and player proximity
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fire_beam_disable_collision_routine_01:
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lda ENEMY_VAR_A,x ; load animation delay
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lda ENEMY_VAR_A,x ; load next attack delay
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sta ENEMY_ANIMATION_DELAY,x ; set enemy animation frame delay counter
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jsr disable_enemy_collision ; prevent player enemy collision check and allow bullets to pass through enemy
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lda #$02 ; a = #$02
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@ -7260,7 +7265,7 @@ fire_beam_left_routine_ptr_tbl:
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fire_beam_left_routine_00:
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lda #$40 ; a = #$40
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jmp fire_beam_add_pos_set_delay
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jmp fire_beam_add_pos_set_delay ; merge #$40 (bit 6) with fire beam enemy attributes and advance routine
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fire_beam_left_routine_01:
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jsr animate_small_flame ; animate small flame when fire beam isn't firing
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@ -7299,37 +7304,40 @@ fire_beam_left_routine_03:
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; pointer table for fire beam right (#$4 * #$2 = #$8 bytes)
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fire_beam_right_routine_ptr_tbl:
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.addr fire_beam_right_routine_00 ; CPU address $aaa4
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.addr fire_beam_right_routine_01 ; CPU address $aaae
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.addr fire_beam_right_routine_02 ; CPU address $aac3
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.addr fire_beam_right_routine_03 ; CPU address $aade
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.addr fire_beam_right_routine_00 ; CPU address $aaa4 - initialize enemy and initial attack delay, then advance routine
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.addr fire_beam_right_routine_01 ; CPU address $aaae - wait for attack delay, then initialize attack and advance routine
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.addr fire_beam_right_routine_02 ; CPU address $aac3 - attack
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.addr fire_beam_right_routine_03 ; CPU address $aade - recede after delay, set new attack delay and go back to fire_beam_right_routine_01
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; initialize enemy and initial attack delay, then advance routine
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fire_beam_right_routine_00:
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lda #$40 ; a = #$40
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sta ENEMY_SPRITE_ATTR,x ; set enemy sprite attributes (flip sprite horizontally)
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lda #$00 ; a = #$00
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jmp fire_beam_add_pos_set_delay
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jmp fire_beam_add_pos_set_delay ; set fire beam collision attribute bit, position, initial attack/animation delay, and advance routine
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; wait for attack delay, then initialize attack and advance routine
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fire_beam_right_routine_01:
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jsr animate_small_flame ; animate small flame when fire beam isn't firing
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jsr add_scroll_to_enemy_pos ; add scrolling to enemy position
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dec ENEMY_ANIMATION_DELAY,x ; decrement enemy animation frame delay counter
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bne fire_beam_right_exit_00
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lda RANDOM_NUM ; load random number
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bne fire_beam_right_exit_00 ; branch if attack delay hasn't elapsed to exit
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lda RANDOM_NUM ; attack delay has elapsed, load random number
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and #$3f ; keep bits ..xx xxxx
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sta ENEMY_VAR_A,x ; set delay between bursts
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jmp begin_fire_beam_attack ; load fire beam length, play sound, clear variables for use
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sta ENEMY_VAR_A,x ; set delay between burst for subsequent attack (re-ignition)
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jmp begin_fire_beam_attack ; load fire beam length, play sound, clear variables for use, and advance routine to attack (ignite)
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; attack
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fire_beam_right_routine_02:
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jsr add_scroll_to_enemy_pos ; add scrolling to enemy position
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ldy #$08 ; y = #$08
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jsr draw_fire_beam_if_anim_elapsed
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bcs fire_beam_right_exit_00
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dec ENEMY_VAR_2,x ; fire beam length
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beq fire_beam_delay_10_adv_routine
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lda ENEMY_VAR_3,x
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adc #$08
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sta ENEMY_VAR_3,x
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dec ENEMY_VAR_2,x ; decrement the current fire beam number of segments
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beq fire_beam_delay_10_adv_routine ; fire beam finished growing, advance routine to shrink back after delay
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lda ENEMY_VAR_3,x ; load horizontal fire beam length
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adc #$08 ; add #$08 to length
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sta ENEMY_VAR_3,x ; update horizontal fire beam length
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fire_beam_right_exit_00:
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rts
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@ -7337,20 +7345,23 @@ fire_beam_right_exit_00:
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fire_beam_delay_10_adv_routine:
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jmp set_fire_beam_delay_10_adv_routine
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; recede after delay, set new attack delay and go back to fire_beam_right_routine_01
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fire_beam_right_routine_03:
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jsr add_scroll_to_enemy_pos ; add scrolling to enemy position
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ldy #$0a ; y = #$0a
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ldy #$0a ; y = #$0a (fire_beam_tile_tbl tile offset)
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jsr draw_fire_beam_if_anim_elapsed
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bcs fire_beam_right_exit_00
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lda ENEMY_VAR_3,x
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sbc #$07
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sta ENEMY_VAR_3,x
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bpl fire_beam_right_exit_00
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jmp fire_beam_disable_collision_routine_01
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lda ENEMY_VAR_3,x ; load horizontal beam length
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sbc #$07 ; subtract #$08 (carry bit set) from horizontal beam length
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sta ENEMY_VAR_3,x ; update horizontal beam length
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bpl fire_beam_right_exit_00 ; exit if flame not fully receded
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jmp fire_beam_disable_collision_routine_01 ; flame fully receded, set attack delay and go back to fire_beam_right_routine_01
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; input
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; * x - current enemy offset
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; * y - fire_beam_tile_tbl offset minus 1
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; output
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; * carry flag - set when delay has not elapsed and fire beam should not yet recede
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draw_fire_beam_if_anim_elapsed:
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lda ENEMY_ANIMATION_DELAY,x ; load enemy animation frame delay counter
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bne set_fire_beam_anim_delay_exit
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@ -7385,14 +7396,14 @@ fire_beam_add_x_length_exit:
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adc $00
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bcc fire_beam_exit
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; draws the fire beam tiles $10 at (a, y)
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; draws the fire beam tiles $10 at (a, y), decrements animation delay
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; input
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; * $10 - level_6_tile_animation offset (tiles to draw)
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; * a - x position to draw tile
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; * y - y position to draw tile
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draw_fire_beam_tiles:
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jsr load_bank_3_update_nametable_tiles ; draw tile code $10 to nametable at (a, y)
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bcs @exit
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bcs @exit ; exit if unable to update nametable tiles
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ldx ENEMY_CURRENT_SLOT ; restore current enemy slot
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lda ENEMY_X_POS,x ; load enemy x position on screen
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cmp #$30 ; see if fire beam is closer to the left edge
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