KEEN_SPEED = $80 YDEFAULT = 20 HARDTOP_TILES = 32 ; start at 32 ALLHARD_TILES = 40 ; start at 40 TILE_COLS = 20 ;========================= ; move keen ;========================= move_keen: lda #0 sta SUPPRESS_WALK ; ???? jsr keen_get_feet_location ; get location of feet jsr check_falling ; check for/handle falling jsr keen_collide ; check for right/left collision jsr handle_jumping ; handle jumping lda KEEN_WALKING ; if not walking, we're done beq done_move_keen dec KEEN_WALKING ; decrement walk count lda SUPPRESS_WALK ; why???? bne done_move_keen lda KEEN_DIRECTION ; check direction bmi move_left ;============================== ; Move Keen Right ;============================== ; if (keen_x<22) || (tilemap_x>xmax-20) walk ; otherwise, scroll lda TILEMAP_X cmp #96 ; 540-80 = 460/4 = 115-20 = 95 bcs keen_walk_right lda KEEN_X ; if X more than 22 cmp #22 ; scroll screen rather than keen bcc keen_walk_right keen_scroll_right: clc ; location is 8:8 fixed point lda KEEN_XL adc #KEEN_SPEED ; add in speed sta KEEN_XL bcc skip_keen_scroll_right ; if carry out we scroll inc TILEMAP_X ; scroll screen to right jsr copy_tilemap_subset ; update tilemap skip_keen_scroll_right: jmp done_move_keen keen_walk_right: lda KEEN_XL ; get 8:8 fixed clc adc #KEEN_SPEED ; add in speed sta KEEN_XL bcc dwr_noflo ; if no overflow inc KEEN_X ; otherwise update X dwr_noflo: jmp done_move_keen move_left: ;============================== ; Move Keen Left ;============================== ; if (keen_x>=14) || (tilemap_x=0) walk ; otherwise, scroll lda TILEMAP_X beq keen_walk_left lda KEEN_X ; get current X cmp #14 bcs keen_walk_left ; bge ; if >=14 walk keen_scroll_left: ; otherwise scroll sec ; 8.8 fixed point lda KEEN_XL sbc #KEEN_SPEED sta KEEN_XL bcs skip_keen_scroll_left dec TILEMAP_X ; scroll left jsr copy_tilemap_subset skip_keen_scroll_left: jmp done_move_keen keen_walk_left: lda KEEN_XL sec sbc #KEEN_SPEED sta KEEN_XL bcs dwl_noflo dec KEEN_X dwl_noflo: jmp done_move_keen done_move_keen: rts ;========================= ; keen collide ;========================= keen_collide: ;================== ; check for item ;================== keen_check_items: jsr check_items ;=================== ; collide with head ;=================== keen_check_head: ; only check above head if jumping lda KEEN_JUMPING beq collide_left_right ; if here we are jumping ; check if left side of head hit hard tile lda KEEN_HEAD_TILE1 ; if tile# < ALLHARD_TILES then we are fine cmp #ALLHARD_TILES bcc collide_left_right ; blt lda KEEN_HEAD_TILE2 ; if tile# < ALLHARD_TILES then we are fine cmp #ALLHARD_TILES bcc collide_left_right ; blt ; o/~ I hit my head, I heard the phone ring o/~ ; o/~ I was distracted by my friend Joe o/~ lda #0 sta KEEN_JUMPING ; no longer jumping lda #1 sta KEEN_FALLING ; now falling ; jsr head_noise collide_left_right: ;=================== ; collide left/right ;=================== lda KEEN_DIRECTION beq done_keen_collide ; can this happen? bmi check_left_collide check_right_collide: lda KEEN_WALK_TILE_R ; if tile# < ALLHARD_TILES then we are fine cmp #ALLHARD_TILES bcc done_keen_collide ; blt lda #1 ; sta SUPPRESS_WALK jmp done_keen_collide check_left_collide: lda KEEN_WALK_TILE_L ; if tile# < ALLHARD_TILES then we are fine cmp #ALLHARD_TILES bcc done_keen_collide ; blt lda #1 sta SUPPRESS_WALK jmp done_keen_collide done_keen_collide: rts ;========================= ; handle_jumping ;========================= handle_jumping: lda KEEN_JUMPING beq done_handle_jumping ; skip if not actually jumping ;=================================================== ; scroll but only if KEEN_Y<20 (YDEFAULT) ; and TILEMAP_Y >0 lda TILEMAP_Y ; if tilemap=0, scroll keen cmp #0 ; instead of scrolling screen beq keen_rising ; check if hit top of screen lda KEEN_Y ; cmp #2 ; if hit top of screen, start falling bcc start_falling cmp #YDEFAULT ; compare to middle of screen bcc scroll_rising ; blt ; move keen keen_rising: dec KEEN_Y dec KEEN_Y jmp done_check_rising scroll_rising: dec TILEMAP_Y jsr copy_tilemap_subset jmp done_check_rising done_check_rising: dec KEEN_JUMPING ; slow jump bne done_handle_jumping ; if positive still going up start_falling: ; otherwise hit peak, start falling lda #1 ; avoid gap before falling triggered sta KEEN_FALLING done_handle_jumping: rts ;========================= ; check_falling ;========================= check_falling: lda KEEN_JUMPING bne done_check_falling ; don't check falling if jumping lda KEEN_FOOT_BELOW1 ; if tile# > HARDTOP_TILES then we stop falling cmp #HARDTOP_TILES bcs feet_on_ground ; bge lda KEEN_FOOT_BELOW2 ; if tile# > HARDTOP_TILES then we stop falling cmp #HARDTOP_TILES bcs feet_on_ground ; bge ;======================= ; falling lda #1 sta KEEN_FALLING ;=================================================== ; scroll but only if KEEN_Y>=20 (YDEFAULT) ; and TILEMAP_Y < MAX_TILE_Y lda TILEMAP_Y cmp #MAX_TILE_Y bcs keen_fall ; bge lda KEEN_Y cmp #YDEFAULT bcs scroll_fall ; bge keen_fall: inc KEEN_Y ; this must be +2 inc KEEN_Y ; as we only draw sprites on even lines jmp done_check_falling scroll_fall: inc TILEMAP_Y jsr copy_tilemap_subset jmp done_check_falling feet_on_ground: ;=========================== ; if had been falling ; make noise ; stop walking? lda KEEN_FALLING beq was_not_falling ; clear falling lda #0 sta KEEN_FALLING sta KEEN_WALKING ; jsr land_noise rts was_not_falling: ; check to see if Y still hi, if so scroll back down ; lda KEEN_Y ; cmp #YDEFAULT ; bcs done_check_falling ; bge ; too high up on screen, adjust down and also adjust tilemap down ; inc KEEN_Y ; inc KEEN_Y ; inc TILEMAP_Y ; share w above? ; jsr copy_tilemap_subset done_check_falling: rts ;======================= ; keen_get_feet_location ;======================= ; sets ? values ; they are actually the tile values, not offsets ; KEEN_HEAD_TILE1, KEEN_HEAD_TILE2 ; tile values of row containing keen's head ; KEEN_FOOT_TILE1, KEEN_FOOT_TILE2 ; tile values of row containing keen's feet ; KEEN_FOOT_BELOW1, KEEN_FOOT_BELOW2 ; tile values of row below keen's feet (he can span 2) ; KEEN_WALK_TILE_L,KEEN_WALK_TILE_R ; tile value of what walking into ; keen sprite is 4 wide, but only the "core" is 2 wide ; so in theory 2 possibilities ; EVEN ODD EVEN ODD ; .KK. .KK. .KK. .KK. ; 001122 001122 001122 00112233 ;FOOT_BELOW 0/1 1/1 1/2 2/2 ;FOOT_WALK(R) 1 2 2 3 ;FOOT_WALK(L) 0 0 1 1 ; if KEEN_X = even ; KEEN_FOOT_BELOW1 = (KEEN_X>>1) ; KEEN_FOOT_BELOW2 = (KEEN_X>>1)+1) ; KEEN_FOOT_WALK_R = (KEEN_X>>1)+1) ; KEEN_FOOT_WALK_L = (KEEN_X>>1) ; if KEEN_X = odd ; KEEN_FOOT_BELOW1 = ((KEEN_X>>1)+1) ; KEEN_FOOT_BELOW2 = ((KEEN_X>>1)+1) ; KEEN_FOOT_WALK_R = ((KEEN_X>>1)+2) ; KEEN_FOOT_WALK_L = (KEEN_X>>1) keen_get_feet_location: lda KEEN_X lsr bcs keen_get_feet_odd keen_get_feet_even: ; carry is clear ldx KEEN_Y adc head_lookup,X tax ; X is now pointer to tile of head lda tilemap,X ; put tilemap value in place sta KEEN_HEAD_TILE1 stx KEEN_HEAD_POINTER_L lda tilemap+1,X sta KEEN_HEAD_TILE2 txa inx stx KEEN_HEAD_POINTER_R ; restore pointer to tile of head clc adc #TILE_COLS ; one row down, now at foot tax lda tilemap,X ; put tilemap value in place sta KEEN_FOOT_TILE1 sta KEEN_WALK_TILE_L stx KEEN_FOOT_POINTER_L lda tilemap+1,X sta KEEN_FOOT_TILE2 sta KEEN_WALK_TILE_R txa inx stx KEEN_FOOT_POINTER_R ; restore pointer to tile of foot clc adc #TILE_COLS ; one row down tax lda tilemap,X sta KEEN_FOOT_BELOW1 lda tilemap+1,X sta KEEN_FOOT_BELOW2 rts keen_get_feet_odd: ; carry is set clc ldx KEEN_Y adc head_lookup,X tax ; X is now pointer to tilemap of head lda tilemap+1,X ; put tilemap value in place sta KEEN_HEAD_TILE1 sta KEEN_HEAD_TILE2 stx KEEN_HEAD_POINTER_L stx KEEN_HEAD_POINTER_R txa clc adc #TILE_COLS ; one row down tax ; X is now pointer to tilemap of feet lda tilemap,X ; put tilemap value in place sta KEEN_WALK_TILE_L lda tilemap+1,X sta KEEN_FOOT_TILE1 sta KEEN_FOOT_TILE2 lda tilemap+2,X sta KEEN_WALK_TILE_R stx KEEN_FOOT_POINTER_L stx KEEN_FOOT_POINTER_R txa clc adc #TILE_COLS ; one row down tax lda tilemap+1,X sta KEEN_FOOT_BELOW1 sta KEEN_FOOT_BELOW2 rts ; xx 0 ; xx 1 ;------ ----- ; xx 0 xx 2 ; xx 1 xx 3 ; xx 2 xx 4 ; xx 3 xx 5 ;------ ------- ; xx 4 xx 6 ; xx 5 xx 7 ; xx 6 ; xx 7 ;----------------------- ; INT((y)/4)*20 head_lookup: .byte 0,0,0,0 .byte 20,20,20,20 ; 3 .byte 40,40,40,40 ; 7 .byte 60,60,60,60 ; 11 .byte 80,80,80,80 ; 15 .byte 100,100,100,100 ; 19 .byte 120,120,120,120 ; 23 .byte 140,140,140,140 ; 27 .byte 160,160,160,160 ; 31 .byte 180,180,180,180 ; 35 .byte 200,200,200,200 ; 39 .byte 220,220,220,220 ; 43 .byte 240,240,240,240 ; 47