859 lines
27 KiB
ArmAsm
859 lines
27 KiB
ArmAsm
; Functions for sprite handling. Mostly maintains the sprite list and provides
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; utility functions to calculate sprite/tile intersections
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;
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; Initialize the sprite data and mask banks (all data = $0000, all masks = $FFFF)
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InitSprites
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ldx #$FFFE
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lda #0
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:loop1 stal spritedata,x
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dex
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dex
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cpx #$FFFE
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bne :loop1
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ldx #$FFFE
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lda #$FFFF
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:loop2 stal spritemask,x
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dex
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dex
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cpx #$FFFE
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bne :loop2
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; Clear values in the sprite array
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ldx #{MAX_SPRITES-1}*2
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:loop3 stz _Sprites+TILE_STORE_ADDR_1,x
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dex
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dex
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bpl :loop3
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; Initialize the VBUFF address offsets in the data and mask banks for each sprite
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;
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; The internal grid 13 tiles wide where each sprite has a 2x2 interior square with a
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; tile-size buffer all around. We pre-render each sprite with all four vert/horz flips
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VBUFF_STRIDE_BYTES equ 13*4
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VBUFF_TILE_ROW_BYTES equ 8*VBUFF_STRIDE_BYTES
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VBUFF_SPRITE_STEP equ VBUFF_TILE_ROW_BYTES*3
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VBUFF_SPRITE_START equ {8*VBUFF_TILE_ROW_BYTES}+4
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ldx #0
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lda #VBUFF_SPRITE_START
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clc
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:loop4 sta _Sprites+VBUFF_ADDR,x
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adc #VBUFF_SPRITE_STEP
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inx
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inx
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cpx #MAX_SPRITES*2
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bcc :loop4
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; Precalculate some bank values
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jsr _CacheSpriteBanks
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rts
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; Add a new sprite to the rendering pipeline
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;
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; The tile id in the range 0 - 511. The top 7 bits are used as sprite control bits
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;
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; Bit 9 : Horizontal flip.
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; Bit 10 : Vertical flip.
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; Bits 11 - 12 : Sprite Size Selector
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; 00 - 8x8 (1x1 tile)
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; 01 - 8x16 (1x2 tiles)
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; 10 - 16x8 (2x1 tiles)
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; 11 - 16x16 (2x2 tiles)
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; Bit 13 : Reserved. Must be zero.
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; Bit 14 : Reserved. Must be zero.
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; Bit 15 : Low Sprite priority. Draws behind high priority tiles.
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;
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; When a sprite has a size > 8x8, the horizontal tiles are taken from the next tile index and
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; the vertical tiles are taken from tileId + 32. This is why tile sheets should be saved
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; with a width of 256 pixels.
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;
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; Single sprite are limited to 24 lines high because there are 28 lines of padding above and below the
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; sprite plane buffers, so a sprite that is 32 lines high could overflow the drawing area.
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;
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; A = tileId + flags
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; X = x position
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; Y = y position
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AddSprite ENT
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phb
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phk
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plb
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jsr _AddSprite
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plb
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rtl
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_AddSprite
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phx ; Save the horizontal position
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ldx _NextOpenSlot ; Get the next free sprite slot index
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bpl :open ; A negative number means we are full
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plx ; Early out
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sec ; Signal that no sprite slot was available
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rts
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:open
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sta _Sprites+SPRITE_ID,x ; Keep a copy of the full descriptor
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jsr _GetBaseTileAddr ; This applies the TILE_ID_MASK
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sta _Sprites+TILE_DATA_OFFSET,x
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lda #SPRITE_STATUS_OCCUPIED+SPRITE_STATUS_ADDED
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sta _Sprites+SPRITE_STATUS,x
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tya
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sta _Sprites+SPRITE_Y,x ; Y coordinate
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pla ; X coordinate
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sta _Sprites+SPRITE_X,x
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jsr _PrecalcAllSpriteInfo ; Cache sprite property values (simple stuff)
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jsr _DrawSpriteSheet ; Render the sprite into internal space
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; Mark the dirty bit to indicate that the active sprite list needs to be rebuilt in the next
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; render call
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lda #DIRTY_BIT_SPRITE_ARRAY
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tsb DirtyBits
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lda _SpriteBits,x ; Get the bit flag for this sprite slot
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tsb SpriteMap ; Mark it in the sprite map bit field
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txa ; And return the sprite ID
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clc ; Mark that the sprite was successfully added
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; We can only get to this point if there was an open slot, so we know we're not at the
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; end of the list yet.
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ldx _OpenListHead
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inx
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inx
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stx _OpenListHead
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ldy _OpenList,x ; If this is the end, then the sentinel value will
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sty _NextOpenSlot ; get stored into _NextOpenSlot
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rts
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; Run through the list of tile store offsets that this sprite was last drawn into and mark
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; those tiles as dirty. The largest number of tiles that a sprite could possibly cover is 20
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; (an unaligned 4x3 sprite), covering a 5x4 area of play field tiles.
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;
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; Y register = sprite record index
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_ClearSpriteFromTileStore
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ldx _Sprites+TILE_STORE_ADDR_1,y
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bne *+3
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rts
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ldal TileStore+TS_SPRITE_FLAG,x ; Clear the bit in the bit field. This seems wasteful, but
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and _SpriteBitsNot,y ; there is no indexed form of TSB/TRB and caching the value in
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stal TileStore+TS_SPRITE_FLAG,x ; a direct page location, only saves 1 or 2 cycles per and costs 10.
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jsr _PushDirtyTileX
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ldx _Sprites+TILE_STORE_ADDR_2,y
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bne *+3
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rts
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ldal TileStore+TS_SPRITE_FLAG,x
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and _SpriteBitsNot,y
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stal TileStore+TS_SPRITE_FLAG,x
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jsr _PushDirtyTileX
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ldx _Sprites+TILE_STORE_ADDR_3,y
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bne *+3
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rts
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ldal TileStore+TS_SPRITE_FLAG,x
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and _SpriteBitsNot,y
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stal TileStore+TS_SPRITE_FLAG,x
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jsr _PushDirtyTileX
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ldx _Sprites+TILE_STORE_ADDR_4,y
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bne *+3
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rts
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ldal TileStore+TS_SPRITE_FLAG,x
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and _SpriteBitsNot,y
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stal TileStore+TS_SPRITE_FLAG,x
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jsr _PushDirtyTileX
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ldx _Sprites+TILE_STORE_ADDR_5,y
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bne *+3
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rts
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ldal TileStore+TS_SPRITE_FLAG,x
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and _SpriteBitsNot,y
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stal TileStore+TS_SPRITE_FLAG,x
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jsr _PushDirtyTileX
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ldx _Sprites+TILE_STORE_ADDR_6,y
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bne *+3
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rts
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ldal TileStore+TS_SPRITE_FLAG,x
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and _SpriteBitsNot,y
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stal TileStore+TS_SPRITE_FLAG,x
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jsr _PushDirtyTileX
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ldx _Sprites+TILE_STORE_ADDR_7,y
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bne *+3
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rts
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ldal TileStore+TS_SPRITE_FLAG,x
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and _SpriteBitsNot,y
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stal TileStore+TS_SPRITE_FLAG,x
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jsr _PushDirtyTileX
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ldx _Sprites+TILE_STORE_ADDR_8,y
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bne *+3
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rts
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ldal TileStore+TS_SPRITE_FLAG,x
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and _SpriteBitsNot,y
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stal TileStore+TS_SPRITE_FLAG,x
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jsr _PushDirtyTileX
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ldx _Sprites+TILE_STORE_ADDR_9,y
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bne *+3
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rts
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ldal TileStore+TS_SPRITE_FLAG,x
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and _SpriteBitsNot,y
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stal TileStore+TS_SPRITE_FLAG,x
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jmp _PushDirtyTileX
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; This function looks at the sprite list and renders the sprite plane data into the appropriate
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; tiles in the code field. There are a few phases to this routine. The assumption is that
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; any sprite that needs to be re-drawn has been marked as DIRTY or DAMAGED.
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;
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; A DIRTY sprite is one that has moved, so it needs to be erased/redrawn in the sprite
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; buffer AND the tiles it covers marked for refresh. A DAMAGED sprite shared one or more
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; tiles with a DIRTY sprite, so it needs to be redraw in the sprite buffer (but not erased!)
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; and its tile do NOT need to be marked for refresh.
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;
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; In the first phase, we run through the list of dirty sprites and erase them from their
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; OLD_VBUFF_ADDR. This clears the sprite plane buffers. We also iterate through the
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; TILE_STORE_ADDR_X array and mark all of the tile store location that this sprite had occupied
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; as dirty, as well as removing this sprite from the TS_SPRITE_FLAG bitfield.
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;
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; A final aspect is that any of the sprites indicated in the TS_SPRITE_FLAG are marked to be
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; drawn in the next phase (since a portion of their content may have been erased if they overlap)
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;
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; In the second phase, the sprite is re-drawn into the sprite plane buffers and the appropriate
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; Tile Store locations are marked as dirty. It is important to recognize that the sprites themselves
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; can be marked dirty, and the underlying tiles in the tile store are independently marked dirty.
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phase1 dw :phase1_0
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dw :phase1_1,:phase1_2,:phase1_3,:phase1_4
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dw :phase1_5,:phase1_6,:phase1_7,:phase1_8
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dw :phase1_9,:phase1_10,:phase1_11,:phase1_12
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dw :phase1_13,:phase1_14,:phase1_15,:phase1_16
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:phase1_16
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ldy activeSpriteList+30
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jsr _DoPhase1
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:phase1_15
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ldy activeSpriteList+28
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jsr _DoPhase1
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:phase1_14
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ldy activeSpriteList+26
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jsr _DoPhase1
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:phase1_13
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ldy activeSpriteList+24
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jsr _DoPhase1
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:phase1_12
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ldy activeSpriteList+22
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jsr _DoPhase1
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:phase1_11
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ldy activeSpriteList+20
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jsr _DoPhase1
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:phase1_10
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ldy activeSpriteList+18
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jsr _DoPhase1
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:phase1_9
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ldy activeSpriteList+16
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jsr _DoPhase1
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:phase1_8
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ldy activeSpriteList+14
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jsr _DoPhase1
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:phase1_7
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ldy activeSpriteList+12
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jsr _DoPhase1
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:phase1_6
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ldy activeSpriteList+10
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jsr _DoPhase1
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:phase1_5
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ldy activeSpriteList+8
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jsr _DoPhase1
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:phase1_4
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ldy activeSpriteList+6
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jsr _DoPhase1
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:phase1_3
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ldy activeSpriteList+4
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jsr _DoPhase1
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:phase1_2
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ldy activeSpriteList+2
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jsr _DoPhase1
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:phase1_1
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ldy activeSpriteList
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jsr _DoPhase1
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:phase1_0
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jmp phase1_rtn
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; If this sprite has been MOVED or REMOVED, then clear its bit from the TS_SPRITE_FLAG in
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; all of the tile store locations that it occupied on the previous frame and add those
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; tile store locations to the dirty tile list.
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_DoPhase1
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lda _Sprites+SPRITE_STATUS,y
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ora forceSpriteFlag
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bit #SPRITE_STATUS_MOVED+SPRITE_STATUS_REMOVED
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beq :no_clear
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jsr _ClearSpriteFromTileStore
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:no_clear
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; Check to see if sprite was REMOVED If so, then this is where we return its Sprite ID to the
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; list of open slots
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lda _Sprites+SPRITE_STATUS,y
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bit #SPRITE_STATUS_REMOVED
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beq :out
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lda #SPRITE_STATUS_EMPTY ; Mark as empty (zero value)
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sta _Sprites+SPRITE_STATUS,y
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lda _SpriteBits,y ; Clear from the sprite bitmap
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trb SpriteMap
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ldx _OpenListHead
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dex
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dex
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stx _OpenListHead
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tya
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sta _OpenList,x
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sty _NextOpenSlot
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:out
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rts
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; Second phase takes care of drawing the sprites and marking the tiles that will need to be merged
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; with pixel data from the sprite plane
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phase2 dw :phase2_0
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dw :phase2_1,:phase2_2,:phase2_3,:phase2_4
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dw :phase2_5,:phase2_6,:phase2_7,:phase2_8
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dw :phase2_9,:phase2_10,:phase2_11,:phase2_12
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dw :phase2_13,:phase2_14,:phase2_15,:phase2_16
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:phase2_16
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ldy activeSpriteList+30
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jsr _DoPhase2
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:phase2_15
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ldy activeSpriteList+28
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jsr _DoPhase2
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:phase2_14
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ldy activeSpriteList+26
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jsr _DoPhase2
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:phase2_13
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ldy activeSpriteList+24
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jsr _DoPhase2
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:phase2_12
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ldy activeSpriteList+22
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jsr _DoPhase2
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:phase2_11
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ldy activeSpriteList+20
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jsr _DoPhase2
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:phase2_10
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ldy activeSpriteList+18
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jsr _DoPhase2
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:phase2_9
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ldy activeSpriteList+16
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jsr _DoPhase2
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:phase2_8
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ldy activeSpriteList+14
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jsr _DoPhase2
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:phase2_7
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ldy activeSpriteList+12
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jsr _DoPhase2
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:phase2_6
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ldy activeSpriteList+10
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jsr _DoPhase2
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:phase2_5
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ldy activeSpriteList+8
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jsr _DoPhase2
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:phase2_4
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ldy activeSpriteList+6
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jsr _DoPhase2
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:phase2_3
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ldy activeSpriteList+4
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jsr _DoPhase2
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:phase2_2
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ldy activeSpriteList+2
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jsr _DoPhase2
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:phase2_1
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ldy activeSpriteList
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jsr _DoPhase2
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:phase2_0
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jmp phase2_rtn
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_DoPhase2
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lda _Sprites+SPRITE_STATUS,y
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beq :out ; If phase 1 marked us as empty, do nothing
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ora forceSpriteFlag
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and #SPRITE_STATUS_ADDED+SPRITE_STATUS_MOVED+SPRITE_STATUS_UPDATED
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beq :out
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; Last thing to do, so go ahead and clear the flags
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lda #SPRITE_STATUS_OCCUPIED
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sta _Sprites+SPRITE_STATUS,y
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; Mark the appropriate tiles as dirty and as occupied by a sprite so that the ApplyTiles
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; subroutine will combine the sprite data with the tile data into the code field where it
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; can be drawn to the screen. This routine is also responsible for setting the specific
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; VBUFF address for each sprite's tile sheet position
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jmp _MarkDirtySprite
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:out
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rts
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; Use the blttmp space to build the active sprite list. Since the sprite tiles are not drawn until later,
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; it's OK to use that scratch space here. And it's just the right size, 32 bytes
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RebuildSpriteArray
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lda SpriteMap ; Get the bit field
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; Unrolled loop to get the sprite index values that coorespond to the set bit positions
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pea $FFFF ; end-of-list marker
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]step equ 0
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lup 4
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lsr
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bcc :skip_1
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pea ]step
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:skip_1 lsr
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bcc :skip_2
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pea ]step+2
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:skip_2 lsr
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bcc :skip_3
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pea ]step+4
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:skip_3 lsr
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bcc :skip_4
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pea ]step+6
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:skip_4 beq :end_1
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]step equ ]step+8
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--^
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:end_1
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; Now pop the values off of the stack until reaching the sentinel value. This could be unrolled, but
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; it is only done once per frame.
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ldx #0
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:loop
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pla
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bmi :out
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sta activeSpriteList,x
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inx
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inx
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bra :loop
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:out
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stx ActiveSpriteCount
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rts
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forceSpriteFlag ds 2
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_RenderSprites
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; Check to see if any sprites have been added or removed. If so, then we regenerate the active
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; sprite list. Since adding and removing sprites is rare, this is a worthwhile tradeoff, because
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; there are several places where we want to iterate over the all of the sprites, and having a list
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; and not have to constantly load and test the SPRITE_STATUS just to skip unused slots can help
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; streamline the code.
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lda #DIRTY_BIT_SPRITE_ARRAY
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trb DirtyBits ; clears the flag, if it was set
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beq :no_rebuild
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jsr RebuildSpriteArray
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:no_rebuild
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; First step is to look at the StartX and StartY values. If the screen has scrolled, then it has
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; the same effect as moving all of the sprites.
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;
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; OPTIMIZATION NOTE: Should check that the sprite actually changes position. If the screen scrolls
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; by +X, but the sprite moves by -X (so it's relative position is unchanged), then
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; it does NOT need to be marked as dirty.
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stz forceSpriteFlag
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lda StartX
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cmp OldStartX
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bne :force_update
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lda StartY
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cmp OldStartY
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beq :no_change
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:force_update
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lda #SPRITE_STATUS_MOVED
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sta forceSpriteFlag
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:no_change
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; Dispatch to the first phase of rendering the sprites. By pre-building the list, we know exactly
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; how many sprite to process and they are in a contiguous array. So we on't have to keep track
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; of an iterating variable
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ldx ActiveSpriteCount
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jmp (phase1,x)
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phase1_rtn
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; Dispatch to the second phase of rendering the sprites.
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ldx ActiveSpriteCount
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jmp (phase2,x)
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phase2_rtn
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; Sprite rendering complete, clear the dirty bits
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rts
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; _GetTileAt
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;
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; Given a relative playfield coordinate [0, ScreenWidth), [0, ScreenHeight) return the
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; X = horizontal point [0, ScreenTileWidth]
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; Y = vertical point [0, ScreenTileHeight]
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;
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; Return
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; C = 1, out of range
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; C = 0, X = column, Y = row
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_GetTileAt
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cpx ScreenWidth
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bcc *+3
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rts
|
|
|
|
cpy ScreenHeight
|
|
bcc *+3
|
|
rts
|
|
|
|
tya ; carry is clear here
|
|
adc StartYMod208 ; This is the code field line that is at the top of the screen
|
|
cmp #208
|
|
bcc *+5
|
|
sbc #208
|
|
|
|
lsr
|
|
lsr
|
|
lsr
|
|
tay ; This is the code field row for this point
|
|
|
|
clc
|
|
txa
|
|
adc StartXMod164
|
|
cmp #164
|
|
bcc *+5
|
|
sbc #164
|
|
|
|
lsr
|
|
lsr
|
|
tax ; Could call _CopyBG0Tile with these arguments
|
|
|
|
clc
|
|
rts
|
|
|
|
; Small initialization routine to cache the banks for the sprite data and mask and tile/sprite stuff
|
|
_CacheSpriteBanks
|
|
lda #>spritemask
|
|
and #$FF00
|
|
ora #^spritedata
|
|
sta SpriteBanks
|
|
|
|
lda #$0100
|
|
ora #^TileStore
|
|
sta TileStoreBankAndBank01
|
|
|
|
lda #>tiledata
|
|
and #$FF00
|
|
ora #^TileStore
|
|
sta TileStoreBankAndTileDataBank
|
|
|
|
rts
|
|
|
|
; This is 13 blocks wide
|
|
SPRITE_PLANE_SPAN equ VBUFF_STRIDE_BYTES ; 52
|
|
|
|
; A = x coordinate
|
|
; Y = y coordinate
|
|
;GetSpriteVBuffAddr ENT
|
|
; jsr _GetSpriteVBuffAddr
|
|
; rtl
|
|
|
|
; A = x coordinate
|
|
; Y = y coordinate
|
|
;_GetSpriteVBuffAddr
|
|
; pha
|
|
; tya
|
|
; clc
|
|
; adc #NUM_BUFF_LINES ; The virtual buffer has 24 lines of off-screen space
|
|
; xba ; Each virtual scan line is 256 bytes wide for overdraw space
|
|
; clc
|
|
; adc 1,s
|
|
; sta 1,s
|
|
; pla
|
|
; rts
|
|
|
|
; Version that uses temporary space (tmp15)
|
|
;_GetSpriteVBuffAddrTmp
|
|
; sta tmp15
|
|
; tya
|
|
; clc
|
|
; adc #NUM_BUFF_LINES ; The virtual buffer has 24 lines of off-screen space
|
|
; xba ; Each virtual scan line is 256 bytes wide for overdraw space
|
|
; clc
|
|
; adc tmp15
|
|
; rts
|
|
|
|
; Precalculate some cached values for a sprite. These are *only* to make other part of code,
|
|
; specifically the draw/erase routines more efficient.
|
|
;
|
|
; There are variations of this routine based on whether we are adding a new sprite, updating
|
|
; it's tile information, or changing its position.
|
|
;
|
|
; X = sprite index
|
|
_PrecalcAllSpriteInfo
|
|
lda _Sprites+SPRITE_ID,x
|
|
and #$3E00
|
|
xba
|
|
sta _Sprites+SPRITE_DISP,x ; use bits 9 through 13 for full dispatch
|
|
|
|
; Set the sprite's width and height
|
|
lda #4
|
|
sta _Sprites+SPRITE_WIDTH,x
|
|
lda #8
|
|
sta _Sprites+SPRITE_HEIGHT,x
|
|
|
|
lda _Sprites+SPRITE_ID,x
|
|
bit #$1000 ; width select
|
|
beq :width_4
|
|
lda #8
|
|
sta _Sprites+SPRITE_WIDTH,x
|
|
:width_4
|
|
|
|
lda _Sprites+SPRITE_ID,x
|
|
bit #$0800 ; width select
|
|
beq :height_8
|
|
lda #16
|
|
sta _Sprites+SPRITE_HEIGHT,x
|
|
:height_8
|
|
|
|
; Clip the sprite's bounding box to the play field size and also set a flag if the sprite
|
|
; is fully off-screen or not
|
|
|
|
lda _Sprites+SPRITE_X,x
|
|
bpl :pos_x
|
|
lda #0
|
|
:pos_x cmp ScreenWidth
|
|
bcs :offscreen ; sprite is off-screen, exit early
|
|
sta _Sprites+SPRITE_CLIP_LEFT,x
|
|
|
|
lda _Sprites+SPRITE_Y,x
|
|
bpl :pos_y
|
|
lda #0
|
|
:pos_y cmp ScreenHeight
|
|
bcs :offscreen ; sprite is off-screen, exit early
|
|
sta _Sprites+SPRITE_CLIP_TOP,x
|
|
|
|
lda _Sprites+SPRITE_X,x
|
|
clc
|
|
adc _Sprites+SPRITE_WIDTH,x
|
|
dec
|
|
bmi :offscreen
|
|
cmp ScreenWidth
|
|
bcc :ok_x
|
|
lda ScreenWidth
|
|
dec
|
|
:ok_x sta _Sprites+SPRITE_CLIP_RIGHT,x
|
|
|
|
lda _Sprites+SPRITE_Y,x
|
|
clc
|
|
adc _Sprites+SPRITE_HEIGHT,x
|
|
dec
|
|
bmi :offscreen
|
|
cmp ScreenHeight
|
|
bcc :ok_y
|
|
lda ScreenHeight
|
|
dec
|
|
:ok_y sta _Sprites+SPRITE_CLIP_BOTTOM,x
|
|
|
|
stz _Sprites+IS_OFF_SCREEN,x ; passed all of the off-screen tests
|
|
|
|
; Calculate the clipped width and height
|
|
lda _Sprites+SPRITE_CLIP_RIGHT,x
|
|
sec
|
|
sbc _Sprites+SPRITE_CLIP_LEFT,x
|
|
inc
|
|
sta _Sprites+SPRITE_CLIP_WIDTH,x
|
|
|
|
lda _Sprites+SPRITE_CLIP_BOTTOM,x
|
|
sec
|
|
sbc _Sprites+SPRITE_CLIP_TOP,x
|
|
inc
|
|
sta _Sprites+SPRITE_CLIP_HEIGHT,x
|
|
rts
|
|
|
|
:offscreen
|
|
lda #1
|
|
sta _Sprites+IS_OFF_SCREEN,x
|
|
rts
|
|
|
|
; Remove a sprite from the list. Just mark its STATUS as FREE and it will be
|
|
; picked up in the next AddSprite.
|
|
;
|
|
; A = Sprite ID
|
|
RemoveSprite ENT
|
|
phb
|
|
phk
|
|
plb
|
|
jsr _RemoveSprite
|
|
plb
|
|
rtl
|
|
|
|
_RemoveSprite
|
|
tax
|
|
|
|
_RemoveSpriteX
|
|
lda _Sprites+SPRITE_STATUS,x
|
|
ora #SPRITE_STATUS_REMOVED
|
|
sta _Sprites+SPRITE_STATUS,x
|
|
rts
|
|
|
|
; Update the sprite's flags. We do not allow the size of a sprite to be changed. That requires
|
|
; the sprite to be removed and re-added.
|
|
;
|
|
; A = Sprite ID
|
|
; X = Sprite Tile ID and Flags
|
|
UpdateSprite ENT
|
|
phb
|
|
phk
|
|
plb
|
|
jsr _UpdateSprite
|
|
plb
|
|
rtl
|
|
|
|
_UpdateSprite
|
|
phx ; swap X/A to be more efficient
|
|
tax
|
|
pla
|
|
|
|
_UpdateSpriteX
|
|
cpx #MAX_SPRITES*2 ; Make sure we're in bounds
|
|
bcc :ok
|
|
rts
|
|
|
|
:ok
|
|
_UpdateSpriteXnc
|
|
cmp _Sprites+SPRITE_ID,x ; Don't do anything if there is no change
|
|
beq :no_sprite_change
|
|
|
|
sta _Sprites+SPRITE_ID,x ; Keep a copy of the full descriptor
|
|
jsr _GetBaseTileAddr ; This applies the TILE_ID_MASK
|
|
cmp _Sprites+TILE_DATA_OFFSET,x
|
|
beq :no_tile_change
|
|
sta _Sprites+TILE_DATA_OFFSET,x
|
|
|
|
jsr _PrecalcAllSpriteInfo ; Cache stuff
|
|
jsr _DrawSpriteSheet ; Render the sprite into internal space if the tile id has changed
|
|
|
|
:no_tile_change
|
|
lda _Sprites+SPRITE_STATUS,x
|
|
ora #SPRITE_STATUS_UPDATED
|
|
sta _Sprites+SPRITE_STATUS,x
|
|
|
|
:no_sprite_change
|
|
rts
|
|
|
|
; Move a sprite to a new location. If the tile ID of the sprite needs to be changed, then
|
|
; a full remove/add cycle needs to happen
|
|
;
|
|
; A = sprite ID
|
|
; X = x position
|
|
; Y = y position
|
|
MoveSprite ENT
|
|
phb
|
|
phk
|
|
plb
|
|
jsr _MoveSprite
|
|
plb
|
|
rtl
|
|
|
|
_MoveSprite
|
|
phx ; swap X/A to be more efficient
|
|
tax
|
|
pla
|
|
|
|
_MoveSpriteX
|
|
cpx #MAX_SPRITES*2 ; Make sure we're in bounds
|
|
bcc :ok
|
|
rts
|
|
|
|
:ok
|
|
_MoveSpriteXnc
|
|
cmp _Sprites+SPRITE_X,x
|
|
bne :changed1
|
|
sta _Sprites+SPRITE_X,x ; Update the X coordinate
|
|
tya
|
|
cmp _Sprites+SPRITE_Y,x
|
|
bne :changed2
|
|
rts
|
|
|
|
:changed1
|
|
sta _Sprites+SPRITE_X,x ; Update the X coordinate
|
|
tya
|
|
:changed2
|
|
sta _Sprites+SPRITE_Y,x ; Update the Y coordinate
|
|
|
|
jsr _PrecalcAllSpriteInfo ; Can be specialized to only update (x,y) values
|
|
|
|
lda _Sprites+SPRITE_STATUS,x
|
|
ora #SPRITE_STATUS_MOVED
|
|
sta _Sprites+SPRITE_STATUS,x
|
|
|
|
rts
|
|
|
|
; Sprite data structures. We cache quite a few pieces of information about the sprite
|
|
; to make calculations faster, so this is hidden from the caller.
|
|
;
|
|
;
|
|
; Number of "off-screen" lines above logical (0,0)
|
|
; NUM_BUFF_LINES equ 24
|
|
|
|
MAX_SPRITES equ 16
|
|
SPRITE_REC_SIZE equ 52
|
|
|
|
; Mark each sprite as ADDED, UPDATED, MOVED, REMOVED depending on the actions applied to it
|
|
; on this frame. Quick note, the same Sprite ID cannot be removed and added in the same frame.
|
|
; A REMOVED sprite if removed from the sprite list during the Render call, so it's ID is not
|
|
; available to the AddSprite function until the next frame.
|
|
|
|
SPRITE_STATUS_EMPTY equ $0000 ; If the status value is zero, this sprite slot is available
|
|
SPRITE_STATUS_OCCUPIED equ $8000 ; Set the MSB to flag it as occupied
|
|
SPRITE_STATUS_ADDED equ $0001 ; Sprite was just added (new sprite)
|
|
SPRITE_STATUS_MOVED equ $0002 ; Sprite's position was changed
|
|
SPRITE_STATUS_UPDATED equ $0004 ; Sprite's non-position attributes were changed
|
|
SPRITE_STATUS_REMOVED equ $0008 ; Sprite has been removed.
|
|
|
|
SPRITE_STATUS equ {MAX_SPRITES*0}
|
|
TILE_DATA_OFFSET equ {MAX_SPRITES*2}
|
|
VBUFF_ADDR equ {MAX_SPRITES*4} ; Fixed address in sprite/mask banks
|
|
SPRITE_ID equ {MAX_SPRITES*6}
|
|
SPRITE_X equ {MAX_SPRITES*8}
|
|
SPRITE_Y equ {MAX_SPRITES*10}
|
|
TILE_STORE_ADDR_1 equ {MAX_SPRITES*12}
|
|
TILE_STORE_ADDR_2 equ {MAX_SPRITES*14}
|
|
TILE_STORE_ADDR_3 equ {MAX_SPRITES*16}
|
|
TILE_STORE_ADDR_4 equ {MAX_SPRITES*18}
|
|
TILE_STORE_ADDR_5 equ {MAX_SPRITES*20}
|
|
TILE_STORE_ADDR_6 equ {MAX_SPRITES*22}
|
|
TILE_STORE_ADDR_7 equ {MAX_SPRITES*24}
|
|
TILE_STORE_ADDR_8 equ {MAX_SPRITES*26}
|
|
TILE_STORE_ADDR_9 equ {MAX_SPRITES*28}
|
|
TILE_STORE_ADDR_10 equ {MAX_SPRITES*30}
|
|
SPRITE_DISP equ {MAX_SPRITES*32} ; pre-calculated index for jmp (abs,x) based on sprite size
|
|
SPRITE_CLIP_LEFT equ {MAX_SPRITES*34}
|
|
SPRITE_CLIP_RIGHT equ {MAX_SPRITES*36}
|
|
SPRITE_CLIP_TOP equ {MAX_SPRITES*38}
|
|
SPRITE_CLIP_BOTTOM equ {MAX_SPRITES*40}
|
|
IS_OFF_SCREEN equ {MAX_SPRITES*42}
|
|
SPRITE_WIDTH equ {MAX_SPRITES*44}
|
|
SPRITE_HEIGHT equ {MAX_SPRITES*46}
|
|
SPRITE_CLIP_WIDTH equ {MAX_SPRITES*48}
|
|
SPRITE_CLIP_HEIGHT equ {MAX_SPRITES*50}
|
|
|
|
; Maintain the index of the next open sprite slot. This allows us to have amortized
|
|
; constant sprite add performance. A negative value means no slots are available.
|
|
_NextOpenSlot dw 0
|
|
_OpenListHead dw 0
|
|
_OpenList dw 0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,$FFFF ; List with sentinel at the end
|
|
|
|
_Sprites ds SPRITE_REC_SIZE*MAX_SPRITES
|