ref: 9b6f57832eac84e602d38179651027bae450b54f
dir: /engine/overworld/map_sprites.asm/
; Loads tile patterns for map's sprites. ; For outside maps, it loads one of several fixed sets of sprites. ; For inside maps, it loads each sprite picture ID used in the map header. ; This is also called after displaying text because loading ; text tile patterns overwrites half of the sprite tile pattern data. ; Note on notation: ; $C1X* and $C2X* are used to denote wSpriteStateData1-wSpriteStateData1 + $ff and wSpriteStateData2 + $00-wSpriteStateData2 + $ff sprite slot ; fields, respectively, within loops. The X is the loop index. ; If there is an inner loop, Y is the inner loop index, i.e. $C1Y* and $C2Y* ; denote fields of the sprite slots iterated over in the inner loop. InitMapSprites: call InitOutsideMapSprites ret c ; return if the map is an outside map (already handled by above call) ; if the map is an inside map (i.e. mapID >= $25) ld hl, wSpriteStateData1 ld de, wSpriteStateData2 + $0d ; Loop to copy picture ID's from $C1X0 to $C2XD for LoadMapSpriteTilePatterns. .copyPictureIDLoop ld a, [hl] ; $C1X0 (picture ID) ld [de], a ; $C2XD ld a, $10 add e ld e, a ld a, $10 add l ld l, a jr nz, .copyPictureIDLoop ; This is used for both inside and outside maps, since it is called by ; InitOutsideMapSprites. ; Loads tile pattern data for sprites into VRAM. LoadMapSpriteTilePatterns: ld a, [wNumSprites] and a ; are there any sprites? jr nz, .spritesExist ret .spritesExist ld c, a ; c = [wNumSprites] ld b, $10 ; number of sprite slots ld hl, wSpriteStateData2 + $0d xor a ld [hFourTileSpriteCount], a .copyPictureIDLoop ; loop to copy picture ID from $C2XD to $C2XE ld a, [hli] ; $C2XD (sprite picture ID) ld [hld], a ; $C2XE ld a, l add $10 ld l, a dec b jr nz, .copyPictureIDLoop ld hl, wSpriteStateData2 + $1e .loadTilePatternLoop ld de, wSpriteStateData2 + $1d ; Check if the current picture ID has already had its tile patterns loaded. ; This done by looping through the previous sprite slots and seeing if any of ; their picture ID's match that of the current sprite slot. .checkIfAlreadyLoadedLoop ld a, e and $f0 ld b, a ; b = offset of the wSpriteStateData2 sprite slot being checked against ld a, l and $f0 ; a = offset of current wSpriteStateData2 sprite slot cp b ; done checking all previous sprite slots? jr z, .notAlreadyLoaded ld a, [de] ; picture ID of the wSpriteStateData2 sprite slot being checked against cp [hl] ; do the picture ID's match? jp z, .alreadyLoaded ld a, e add $10 ld e, a jr .checkIfAlreadyLoadedLoop .notAlreadyLoaded ld de, wSpriteStateData2 + $0e ld b, $01 ; loop to find the highest tile pattern VRAM slot (among the first 10 slots) used by a previous sprite slot ; this is done in order to find the first free VRAM slot available .findNextVRAMSlotLoop ld a, e add $10 ld e, a ld a, l cp e ; reached current slot? jr z, .foundNextVRAMSlot ld a, [de] ; $C2YE (VRAM slot) cp 11 ; is it one of the first 10 slots? jr nc, .findNextVRAMSlotLoop cp b ; compare the slot being checked to the current max jr c, .findNextVRAMSlotLoop ; if the slot being checked is less than the current max ; if the slot being checked is greater than or equal to the current max ld b, a ; store new max VRAM slot jr .findNextVRAMSlotLoop .foundNextVRAMSlot inc b ; increment previous max value to get next VRAM tile pattern slot ld a, b ; a = next VRAM tile pattern slot push af ld a, [hl] ; $C2XE (sprite picture ID) ld b, a ; b = current sprite picture ID cp SPRITE_BALL ; is it a 4-tile sprite? jr c, .notFourTileSprite pop af ld a, [hFourTileSpriteCount] add 11 jr .storeVRAMSlot .notFourTileSprite pop af .storeVRAMSlot ld [hl], a ; store VRAM slot at $C2XE ld [hVRAMSlot], a ; used to determine if it's 4-tile sprite later ld a, b ; a = current sprite picture ID dec a add a add a push bc push hl ld hl, SpriteSheetPointerTable jr nc, .noCarry inc h .noCarry add l ld l, a jr nc, .noCarry2 inc h .noCarry2 push hl call ReadSpriteSheetData push af push de push bc ld hl, vNPCSprites ; VRAM base address ld bc, $c0 ; number of bytes per VRAM slot ld a, [hVRAMSlot] cp 11 ; is it a 4-tile sprite? jr nc, .fourTileSpriteVRAMAddr ld d, a dec d ; Equivalent to multiplying $C0 (number of bytes in 12 tiles) times the VRAM ; slot and adding the result to $8000 (the VRAM base address). .calculateVRAMAddrLoop add hl, bc dec d jr nz, .calculateVRAMAddrLoop jr .loadStillTilePattern .fourTileSpriteVRAMAddr ld hl, vSprites + $7c0 ; address for second 4-tile sprite ld a, [hFourTileSpriteCount] and a jr nz, .loadStillTilePattern ; if it's the first 4-tile sprite ld hl, vSprites + $780 ; address for first 4-tile sprite inc a ld [hFourTileSpriteCount], a .loadStillTilePattern pop bc pop de pop af push hl push hl ld h, d ld l, e pop de ld b, a ld a, [wFontLoaded] bit 0, a ; reloading upper half of tile patterns after displaying text? jr nz, .skipFirstLoad ; if so, skip loading data into the lower half ld a, b ld b, 0 call FarCopyData2 ; load tile pattern data for sprite when standing still .skipFirstLoad pop de pop hl ld a, [hVRAMSlot] cp 11 ; is it a 4-tile sprite? jr nc, .skipSecondLoad ; if so, there is no second block push de call ReadSpriteSheetData push af ld a, $c0 add e ld e, a jr nc, .noCarry3 inc d .noCarry3 ld a, [wFontLoaded] bit 0, a ; reloading upper half of tile patterns after displaying text? jr nz, .loadWhileLCDOn pop af pop hl set 3, h ; add $800 to hl push hl ld h, d ld l, e pop de call FarCopyData2 ; load tile pattern data for sprite when walking jr .skipSecondLoad ; When reloading the upper half of tile patterns after displaying text, the LCD ; will be on, so CopyVideoData (which writes to VRAM only during V-blank) must ; be used instead of FarCopyData2. .loadWhileLCDOn pop af pop hl set 3, h ; add $800 to hl ld b, a swap c call CopyVideoData ; load tile pattern data for sprite when walking .skipSecondLoad pop hl pop bc jr .nextSpriteSlot .alreadyLoaded ; if the current picture ID has already had its tile patterns loaded inc de ld a, [de] ; a = VRAM slot for the current picture ID (from $C2YE) ld [hl], a ; store VRAM slot in current wSpriteStateData2 sprite slot (at $C2XE) .nextSpriteSlot ld a, l add $10 ld l, a dec c jp nz, .loadTilePatternLoop ld hl, wSpriteStateData2 + $0d ld b, $10 ; the pictures ID's stored at $C2XD are no longer needed, so zero them .zeroStoredPictureIDLoop xor a ld [hl], a ; $C2XD ld a, $10 add l ld l, a dec b jr nz, .zeroStoredPictureIDLoop ret ; reads data from SpriteSheetPointerTable ; INPUT: ; hl = address of sprite sheet entry ; OUTPUT: ; de = pointer to sprite sheet ; bc = length in bytes ; a = ROM bank ReadSpriteSheetData: ld a, [hli] ld e, a ld a, [hli] ld d, a ld a, [hli] ld c, a xor a ld b, a ld a, [hli] ret ; Loads sprite set for outside maps (cities and routes) and sets VRAM slots. ; sets carry if the map is a city or route, unsets carry if not InitOutsideMapSprites: ld a, [wCurMap] cp REDS_HOUSE_1F ; is the map a city or a route (map ID less than $25)? ret nc ; if not, return ld hl, MapSpriteSets add l ld l, a jr nc, .noCarry inc h .noCarry ld a, [hl] ; a = spriteSetID cp $f0 ; does the map have 2 sprite sets? call nc, GetSplitMapSpriteSetID ; if so, choose the appropriate one ld b, a ; b = spriteSetID ld a, [wFontLoaded] bit 0, a ; reloading upper half of tile patterns after displaying text? jr nz, .loadSpriteSet ; if so, forcibly reload the sprite set ld a, [wSpriteSetID] cp b ; has the sprite set ID changed? jr z, .skipLoadingSpriteSet ; if not, don't load it again .loadSpriteSet ld a, b ld [wSpriteSetID], a dec a ld b, a sla a ld c, a sla a sla a add c add b ; a = (spriteSetID - 1) * 11 ld de, SpriteSets ; add a to de to get offset of sprite set add e ld e, a jr nc, .noCarry2 inc d .noCarry2 ld hl, wSpriteStateData2 + $0d ld a, SPRITE_RED ld [hl], a ld bc, wSpriteSet ; Load the sprite set into RAM. ; This loop also fills $C2XD (sprite picture ID) where X is from $0 to $A ; with picture ID's. This is done so that LoadMapSpriteTilePatterns will ; load tile patterns for all sprite pictures in the sprite set. .loadSpriteSetLoop ld a, $10 add l ld l, a ld a, [de] ; sprite picture ID from sprite set ld [hl], a ; $C2XD (sprite picture ID) ld [bc], a inc de inc bc ld a, l cp $bd ; reached 11th sprite slot? jr nz, .loadSpriteSetLoop ld b, 4 ; 4 remaining sprite slots .zeroRemainingSlotsLoop ; loop to zero the picture ID's of the remaining sprite slots ld a, $10 add l ld l, a xor a ld [hl], a ; $C2XD (sprite picture ID) dec b jr nz, .zeroRemainingSlotsLoop ld a, [wNumSprites] push af ; save number of sprites ld a, 11 ; 11 sprites in sprite set ld [wNumSprites], a call LoadMapSpriteTilePatterns pop af ld [wNumSprites], a ; restore number of sprites ld hl, wSpriteStateData2 + $1e ld b, $0f ; The VRAM tile pattern slots that LoadMapSpriteTilePatterns set are in the ; order of the map's sprite set, not the order of the actual sprites loaded ; for the current map. So, they are not needed and are zeroed by this loop. .zeroVRAMSlotsLoop xor a ld [hl], a ; $C2XE (VRAM slot) ld a, $10 add l ld l, a dec b jr nz, .zeroVRAMSlotsLoop .skipLoadingSpriteSet ld hl, wSpriteStateData1 + $10 ; This loop stores the correct VRAM tile pattern slots according the sprite ; data from the map's header. Since the VRAM tile pattern slots are filled in ; the order of the sprite set, in order to find the VRAM tile pattern slot ; for a sprite slot, the picture ID for the sprite is looked up within the ; sprite set. The index of the picture ID within the sprite set plus one ; (since the Red sprite always has the first VRAM tile pattern slot) is the ; VRAM tile pattern slot. .storeVRAMSlotsLoop ld c, 0 ld a, [hl] ; $C1X0 (picture ID) (zero if sprite slot is not used) and a ; is the sprite slot used? jr z, .skipGettingPictureIndex ; if the sprite slot is not used ld b, a ; b = picture ID ld de, wSpriteSet ; Loop to find the index of the sprite's picture ID within the sprite set. .getPictureIndexLoop inc c ld a, [de] inc de cp b ; does the picture ID match? jr nz, .getPictureIndexLoop inc c .skipGettingPictureIndex push hl inc h ld a, $0e add l ld l, a ld a, c ; a = VRAM slot (zero if sprite slot is not used) ld [hl], a ; $C2XE (VRAM slot) pop hl ld a, $10 add l ld l, a and a jr nz, .storeVRAMSlotsLoop scf ret ; Chooses the correct sprite set ID depending on the player's position within ; the map for maps with two sprite sets. GetSplitMapSpriteSetID: cp $f8 jr z, .route20 ld hl, SplitMapSpriteSets and $0f dec a sla a sla a add l ld l, a jr nc, .noCarry inc h .noCarry ld a, [hli] ; determines whether the map is split East/West or North/South cp $01 ld a, [hli] ; position of dividing line ld b, a jr z, .eastWestDivide .northSouthDivide ld a, [wYCoord] jr .compareCoord .eastWestDivide ld a, [wXCoord] .compareCoord cp b jr c, .loadSpriteSetID ; if in the East side or South side inc hl .loadSpriteSetID ld a, [hl] ret ; Uses sprite set $01 for West side and $0A for East side. ; Route 20 is a special case because the two map sections have a more complex ; shape instead of the map simply being split horizontally or vertically. .route20 ld hl, wXCoord ld a, [hl] cp $2b ld a, $01 ret c ld a, [hl] cp $3e ld a, $0a ret nc ld a, [hl] cp $37 ld b, $08 jr nc, .next ld b, $0d .next ld a, [wYCoord] cp b ld a, $0a ret c ld a, $01 ret INCLUDE "data/sprite_sets.asm"