Sparse Invaders Source SpriteControllert.txt - simondotm/stardot-wiki GitHub Wiki
The Sprite Controller manages any active sprites. This was the first module I really implemented when first working on the Sparse Invaders. That's really trying to explain that it's a little overly complex for the Beeb. In Sparse Invaders, the only sprites under this controller are the player, bullets, mothership and explosions. If you are to use this sprite controller then please be aware that it has limitations. To keep the game running faster the Invaders are drawn using a much more simplier and faster technique. However that said, when initializing the sprite, it does pre-calculate and store certain parameters within the sprite structure to speed things along alittle when drawing the sprite. There are certainly pro's and con's when using this controller, however for simple games this more then does the job.
Please refer to constants.txt for details for the sprite structure.
;-------------------------------------------------------------------------------
; SpriteController
; Written by Neil Beresford.
;
; Copyright 2008,2009 Neil Beresford
;
; This file is part of Sparse Invaders.
; Sparse Invaders is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; Sparse Invaders is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with Sparse Invaders. If not, see <http://www.gnu.org/licenses/>.
;
;
; Notes:
;
; Sprite fix array, screen active list
;
; Functionality...
; Sprite core system:
; SpriteInit - pressetup for sprite system - holds test code at present.
; SpriteStart - Adds sprite into control system
; SpritesDrawActive - Draws all activate sprites - max limit of 6
; SpritesWipeActive - Wipes the area that the sprite was drawn to
; SpriteDraw - sprite drawer
; SpriteWipe - sprite wipe
;
; Support Functionality;
; SpriteClear - clears the sprite structure within the active array
; SpriteActivate - marks the active position within
; SpriteCalcScreenPos - calculates the screen position address from X,Y
; SpriteRetreiveDetails- gets the sprite data, width and height for the sprite from its data
;
;-------------------------------------------------------------------------------
.require "Constands"
.require "Macros"
;-------------------------------------------------------------------------------
; SpriteInit -
; inits the sprite system
;
;-------------------------------------------------------------------------------
SpriteInit:
; clear the sprite data ...
; [NOTE] this assumes at present, less then 255 bytes for the data ...
LDA #0
LDX #TOTAL_SPRITE_SPACE
SI_Clearlist:
DEX
STA SPRArray,X
BNE SI_Clearlist
; clear the active list ...
LDX #TOTAL_ACTIVE_SPRITES - 1
LDA #$ff
SI_ClearActives:
STA SPRActive,X
DEX
BPL SI_ClearActives
RTS
;-------------------------------------------------------------------------------
; SpriteStart:
; Starts the sprite, activating it...
; Regs - A sprite number for storage. (SprArray)
; X sprite X
; Y sprite Y
; SPRITE sprite frame <--- SPRITE is in Zero page
; CALLPARMA1 used for the callback for the control...
; CALLPARMA2 ... ( have blank if not needed )
;-------------------------------------------------------------------------------
SpriteStart:
CLC
ROL
ROL
ROL
ROL
STA SCRATCH1
STX XPOS
STY YPOS
JSR SpriteClear
LDA SCRATCH1
JSR SPriteActivate
STX CURRENT_SPRITE
CLC
LDA #<SPRArray
ADC SCRATCH1
STA TEMPPTR
LDA #>`SPRArray`
ADC #0
STA TEMPPTR+1
LDY #0
LDA XPOS ; 0 Xpos
STA (TEMPPTR), Y
INY
LDA YPOS ; 1 Ypos
STA (TEMPPTR), Y
INY
LDA SPRITE ; 2 frame
STA (TEMPPTR), Y
INY
LDA CALLPARAM1 ; 3 control
STA (TEMPPTR), Y
LDA CALLPARAM2
INY
STA (TEMPPTR), Y ; 4 ...
; PLEASE PLEASE do not move this away from the YPOS adjust as I did! Sigh!
LDA SPRITE
JSR SpriteRetreiveDetails
LDY #SPRBLK_WIDTH
STA (TEMPPTR), Y ; store width
TXA
INY
STA (TEMPPTR), Y ; store height
; adjust Y pos to bottom of sprite,
CLC
ADC YPOS
SEC
SBC #1
STA YPOS
; adjust the YPOS to character based and store the offset in x for indexing
AND #$07
STA XOFFSET
LDA YPOS
AND #$f8
STA YPOS
jsr SpriteCalcScreenPos
LDA #SPRFLAG_REDRAW
LDY #SPRBLK_FLAG
STA (TEMPPTR), Y ; Mark the sprite for redraw
LDY #SPRBLK_SPRDATA
LDA CURRENTSPRITEDATA
STA (TEMPPTR),Y ; store sprite data
INY
LDA CURRENTSPRITEDATA+1
STA (TEMPPTR),Y
LDY #SPRBLK_XOFFSET ; Xoffset
LDA XOFFSET
STA (TEMPPTR),Y
LDY #SPRBLK_XOFFBACK
STA (TEMPPTR),Y
LDA SCREENADD ; 6 SCREEN ADD
LDY #SPRBLK_SCREENADD
STA (TEMPPTR),Y
INY
LDA SCREENADD+1 ; 7 /\ /\
STA (TEMPPTR),Y
LDY #SPRBLK_SCRBACK ; screen position used for wiping spr
LDA SCREENADD
STA (TEMPPTR),Y
INY
LDA SCREENADD+1
STA (TEMPPTR),Y
SI_Debug:
RTS
;-------------------------------------------------------------------------------
; SpriteMoveSprite -
; Moves the sprite to the adsolute pos passed in
; A - sprite slot index ( sprite * 8 )
; X - x pos
; y - y pos
;-------------------------------------------------------------------------------
SpriteMoveSprite:
CLC
ROL
ROL
ROL
ROL
STA SCRATCH1
STX XPOS
STY YPOS
CLC
LDA #<SPRArray
ADC SCRATCH1
STA TEMPPTR
LDA #>`SPRArray`
ADC #0
STA TEMPPTR+1
SpriteMoveSpr:
; store the x and y position
LDA XPOS
LDY #SPRBLK_X
STA (TEMPPTR), Y
LDA YPOS
INY
STA (TEMPPTR), Y
; get the width and height for drawing the sprite
LDY #SPRBLK_WIDTH
LDA (TEMPPTR), Y
STA WIDTH
INY
LDA (TEMPPTR), Y
STA HEIGHT
; adjust Y pos to bottom of sprite,
CLC
ADC YPOS
SEC
SBC #1
STA YPOS
; adjust the YPOS to character based and store the offset in x for indexing
AND #$07
STA XOFFSET
LDA YPOS
AND #$f8
STA YPOS
jsr SpriteCalcScreenPos
LDA XOFFSET
LDY #SPRBLK_XOFFSET ; 5 Xoffset
STA (TEMPPTR),Y
LDA SCREENADD ; 6 SCREEN ADD
INY
STA (TEMPPTR),Y
LDA SCREENADD+1 ; 7 /\ /\
INY
STA (TEMPPTR),Y
LDY #SPRBLK_FLAG
LDA (TEMPPTR), Y
ORA #SPRFLAG_REDRAW
STA (TEMPPTR), Y ; Mark the sprite for redraw
RTS
;-------------------------------------------------------------------------------
; SpriteActivate -
; Activates the sprite slot
; A - sprite slot index ( sprite * 8 )
;-------------------------------------------------------------------------------
SpriteActivate:
TAY
LDX #TOTAL_ACTIVE_SPRITES-1
LDA #$ff
SA_Loop:
CMP SPRActive,X
BEQ SA_found
DEX
BPL SA_loop
RTS
SA_found:
TYA
STA SPRActive,X
RTS
;-------------------------------------------------------------------------------
; SpriteClear -
; clears sprite data and removes from active list if present..
; A - sprite slot indexed ( sprite * 16 )
;
;-------------------------------------------------------------------------------
SpriteClear:
PHA
; firstly check and remove if found in active list
LDX #TOTAL_ACTIVE_SPRITES-1
SC_checkActive:
CMP SPRActive,X
BNE SC_decIndex
SC_foundActive:
LDA #$ff
STA SPRActive,X
; now clear the sprite slot ...
PLA
SC_ClearData:
STA SCRATCH1
LDA #<SPRArray
CLC
ADC SCRATCH1
STA TEMPPTR
LDA #>`SPRArray`
ADC #0
STA TEMPPTR+1
LDY #SIZEOF_SPRITE_BLOCK -1
SC_clear:
STA (TEMPPTR),Y
DEY
BPL SC_clear
RTS
SC_decIndex:
DEX
BPL SC_checkActive
PLA ; pop stack...
RTS
;-------------------------------------------------------------------------------
; SpriteDrawActive
; worth through the active sprites, drawing any that are needed.
;-------------------------------------------------------------------------------
SpritesDrawActive:
; firstly check and remove if found in active list
LDX #TOTAL_ACTIVE_SPRITES-1
SDA_Loop:
STX ACTIVEINDEX
LDA SPRActive,X
CMP #$ff
BEQ SDA_Next
SDA_Found:
; calculate the offset to the start of active sprite data
STA SPRITE
CLC
LDA #<SPRArray
ADC SPRITE
STA TEMPPTR
LDA #>`SPRArray`
ADC #0
STA TEMPPTR+1
LDY #SPRBLK_FLAG
LDA (TEMPPTR),Y
AND #SPRFLAG_REDRAW
BEQ SDA_Next
STX SCRATCH1
jsr SDA_SetupSprite
LDX STOREX
LDY STOREY
; draw the sprite to screen...
JSR SpriteDraw
; clear the redraw flag...
LDY #SPRBLK_FLAG
LDA (TEMPPTR),Y
AND #SPRFLAG_NOT_REDRAW
STA (TEMPPTR),Y
LDY #SPRBLK_CTRL
LDA (TEMPPTR),Y
BEQ SDA_Next
STA USERPTR
INY
LDA (TEMPPTR),Y
STA USERPTR+1
; NOTE - RTS pops the low then high byte, adds one
; then sets the PC to that address. The example in
; 6502.org shows the high byte od SDA_Return with -1
; on it as well. I can only assume it's parsed left
; to right - I'm concerned if this address falls on a 256
; boundary.
; might be a bug in p65 - investigate later, as address calculated
; correctly as of writting.
LDA #>SDA_Return
PHA
LDA #<SDA_Return-1
PHA
JMP (USERPTR)
SDA_Return:
SDA_Next:
LDX ACTIVEINDEX
DEX
BPL SDA_Loop
RTS
SDA_SetupSprite:
; get the x and y and frame for drawing the sprite
LDY #0
LDA (TEMPPTR), Y
STA STOREX
INY
LDA (TEMPPTR), Y
STA STOREY
INY
LDA (TEMPPTR), Y
TAX ; frame saved
; retrieve the screen position for drawing the sprite ...
LDY #SPRBLK_XOFFSET ; sprite screen drawing
LDA (TEMPPTR), Y
STA XOFFSET
INY
LDA (TEMPPTR), Y
STA SCREENADD
STA SCREENADD_BACK
INY
LDA (TEMPPTR), Y
STA SCREENADD+1
STA SCREENADD_BACK+1
LDY #SPRBLK_WIDTH ; sprite width and height
LDA (TEMPPTR), Y
STA WIDTH
STA CURRENT_SPR_W
INY
LDA (TEMPPTR), Y
STA HEIGHT
STA CURRENT_SPR_H
LDY #SPRBLK_SPRDATA ; sprite data
LDA (TEMPPTR),Y
STA CURRENTSPRITEDATA
INY
LDA (TEMPPTR),Y
STA CURRENTSPRITEDATA+1
TXA
RTS
;-------------------------------------------------------------------------------
; SpriteWipeActive
; worth through the active sprites, clearing any that are needed.
;-------------------------------------------------------------------------------
SpritesWipeActive:
; firstly check and remove if found in active list
LDX #TOTAL_ACTIVE_SPRITES-1
SWA_Loop:
STX ACTIVEINDEX
LDA #$ff
CMP SPRActive,X
BEQ SWA_Next
SWA_Found:
LDA SPRActive,X
STA SPRITE
; check the redraw flag ...
CLC
ADC #SPRBLK_FLAG
TAX
LDA SPRArray,X
AND #SPRFLAG_REDRAW
BEQ SWA_Next
; clear the sprite to screen...
LDA SPRITE
JSR SpriteWipe
;
; tempptr has been set within the spritewipe function
; Set the new screen position to be the old one ...
LDY #SPRBLK_FLAG
LDA (TEMPPTR),Y
AND #SPRFLAG_KILL
BEQ SWA_SetScreen
; kill sprite ... remove from list
LDX ACTIVEINDEX
LDA #$ff
STA SprActive,X
JMP SWA_Next
SWA_SetScreen:
LDY #SPRBLK_SCREENADD
LDA (TEMPPTR),Y
LDY #SPRBLK_SCRBACK
STA (TEMPPTR),Y
LDY #SPRBLK_SCREENADD2
LDA (TEMPPTR),Y
LDY #SPRBLK_SCRBACK2
STA (TEMPPTR),Y
LDY #SPRBLK_XOFFSET
LDA (TEMPPTR),Y
LDY #SPRBLK_XOFFBACK
STA (TEMPPTR),Y
SWA_Next:
LDX ACTIVEINDEX
DEX
BPL SWA_Loop
RTS
;-------------------------------------------------------------------------------
; SpriteRetreiveDetails - a Sprite number
; returns A - width, X - heighht
;
;-------------------------------------------------------------------------------
SpriteRetreiveDetails:
; calculate the index...
ASL
TAX
CLC
; get and store the pointer to the sprtie data ...
LDA spriteData,X
ADC #<spriteData
STA CURRENTSPRITEDATA
INX
LDA spriteData,X
ADC #>`spriteData`
STA CURRENTSPRITEDATA+1
; grab the sprite info ...
LDY #SPRDATA_HEIGHT
LDA (CURRENTSPRITEDATA),Y
TAX
DEY
LDA (CURRENTSPRITEDATA),Y
RTS
;-------------------------------------------------------------------------------
; SpriteDraw - a Sprite number = referenced from SPRArray
; The following need to be setup prior to calling this...
; SPRITEADD, WIDTH, HEIGHT, XOFFSET, CURRENTSPRITEDATA
;-------------------------------------------------------------------------------
SpriteDraw:
; store the sprite number, x and y position
STA SPRITE
STX XPOS
STY YPOS
; now store sprite data and screen address in code
LDA SCREENADD
STA ScreenAddPtr+1
LDA SCREENADD+1
STA ScreenAddPtr+2
CLC
LDA CURRENTSPRITEDATA
ADC #2
STA SpriteDataPtr+1
LDA CURRENTSPRITEDATA+1
ADC #0
STA SpriteDataPtr+2
LDX XOFFSET
SW_Width:
LDY HEIGHT
DEY
SW_Height:
SpriteDataPtr: ; please note - self modifying code
LDA $FFFF,Y
BEQ SW_SkipWrite
ScreenAddPtr: ; please note - self modifying code
STA $FFFF,X ; is -> STA ScreenAddPtr+1,X
SW_SkipWrite:
DEX
BPL SW_CheckHeight
SW_AtCharPos:
SEC
LDA ScreenAddPtr+1
SBC #$80
STA ScreenAddPtr+1
LDA ScreenAddPtr+2
SBC #2
STA SCreenAddPtr+2
LDX #7
SW_CheckHeight:
DEY
BPL SW_Height
DEC WIDTH
BEQ SW_End
; move to the next column
CLC
LDA SpriteDataPtr+1
ADC HEIGHT
STA SpriteDataPtr+1
LDA SpriteDataPtr+2
ADC #0
STA SpriteDataPtr+2
LDA SCREENADD
CLC
ADC #8
STA SCREENADD
STA ScreenAddPtr+1
LDA SCREENADD+1
ADC #0
STA SCREENADD+1
STA ScreenAddPtr+2
LDX XOFFSET
JMP SW_Width
SW_End:
RTS
;-------------------------------------------------------------------------------
; SpriteNoMaskDraw - a Sprite number = referenced from SPRArray
; The following need to be setup prior to calling this...
; SPRITEADD, WIDTH, HEIGHT, XOFFSET, CURRENTSPRITEDATA
;-------------------------------------------------------------------------------
SpriteNoMaskDraw:
; store the sprite number, x and y position
STA SPRITE
STX XPOS
STY YPOS
; now store sprite data and screen address in code
LDA SCREENADD
STA SScreenAddPtr+1
LDA SCREENADD+1
STA SScreenAddPtr+2
CLC
LDA CURRENTSPRITEDATA
ADC #2
STA SSpriteDataPtr+1
LDA CURRENTSPRITEDATA+1
ADC #0
STA SSpriteDataPtr+2
LDX XOFFSET
SNMW_Width:
LDY HEIGHT
DEY
SNMW_Height:
SSpriteDataPtr: ; please note - self modifying code
LDA $FFFF,Y
SScreenAddPtr: ; please note - self modifying code
STA $FFFF,X ; is -> STA ScreenAddPtr+1,X
DEX
BPL SNMW_CheckHeight
SNMW_AtCharPos:
SEC
LDA SScreenAddPtr+1
SBC #$80
STA SScreenAddPtr+1
LDA SScreenAddPtr+2
SBC #2
STA SSCreenAddPtr+2
LDX #7
SNMW_CheckHeight:
DEY
BPL SNMW_Height
DEC WIDTH
BEQ SNMW_End
; move to the next column
CLC
LDA SSpriteDataPtr+1
ADC HEIGHT
STA SSpriteDataPtr+1
LDA SSpriteDataPtr+2
ADC #0
STA SSpriteDataPtr+2
LDA SCREENADD
CLC
ADC #8
STA SCREENADD
STA SScreenAddPtr+1
LDA SCREENADD+1
ADC #0
STA SCREENADD+1
STA SScreenAddPtr+2
LDX XOFFSET
JMP SNMW_Width
SNMW_End:
RTS
;-------------------------------------------------------------------------------
; SpriteWipe - a Sprite number
;-------------------------------------------------------------------------------
SpriteWipe:
STA SCRATCH1
CLC
LDA #<SPRArray
ADC SCRATCH1
STA TEMPPTR
LDA #>`SPRArray`
ADC #0
STA TEMPPTR+1
LDY #SPRBLK_XOFFBACK
LDA (TEMPPTR),Y
STA XOFFSET
LDY #SPRBLK_SCRBACK
LDA (TEMPPTR),Y
STA SCREENADD
INY
LDA (TEMPPTR),Y
STA SCREENADD+1
LDY #SPRBLK_WIDTH
LDA (TEMPPTR),Y
STA WIDTH
INY
LDA (TEMPPTR),Y
STA HEIGHT
Sprite_Blank:
; now store screen address in code
LDA SCREENADD
STA ScreenAddPtr2+1
LDA SCREENADD+1
STA ScreenAddPtr2+2
LDX XOFFSET
SWipe_Width:
LDY HEIGHT
DEY
SWipe_Height:
LDA #$00
ScreenAddPtr2: ; please note - self modifying code
STA $FFFF,X ; is -> STA ScreenAddPtr+1,X
SWipe_SkipWrite:
DEX
BPL SWipe_CheckHeight
SWipe_AtCharPos:
SEC
LDA ScreenAddPtr2+1
SBC #$80
STA ScreenAddPtr2+1
LDA ScreenAddPtr2+2
SBC #2
STA SCreenAddPtr2+2
LDX #7
SWipe_CheckHeight:
DEY
BPL SWipe_Height
DEC WIDTH
BEQ SWipe_End
; move to the next column
LDA SCREENADD
CLC
ADC #8
STA SCREENADD
STA ScreenAddPtr2+1
LDA SCREENADD+1
ADC #0
STA SCREENADD+1
STA ScreenAddPtr2+2
LDX XOFFSET
JMP SWipe_Width
SWipe_End:
RTS
;-------------------------------------------------------------------------------
; SpriteCalcScreenPos:
; calculates the screen address - please note that
; xpos($75) and ypos($76) need to be set up before.
; This also uses $70+$71 for the screen address ( screenAdd )
;
;-------------------------------------------------------------------------------
SpriteCalcScreenPos:
; reset the screen address ...
LDA #SCREENLOW
STA SCREENADD
LDA #SCREENHIGH
STA SCREENADD+1
; now calculate the Y position in chars ( *640 ) and add
; to the screen Address
LDA YPOS
AND #$f8
LSR
LSR
TAY
CLC
LDA LookUp640, Y
ADC SCREENADD
STA SCREENADD
INY
LDA LookUp640,Y
ADC SCREENADD+1
STA SCREENADD+1
; now the X multiply then addition to screen address
`MUL8ADDTOADDRESS XPOS, SCREENADD
; finally the first 3 bits of the YPos
LDA YPOS
AND #$07
CLC
ADC SCREENADD
STA SCREENADD
LDA SCREENADD
STA SCREENADD_BACK
LDA SCREENADD+1
STA SCREENADD_BACK+1
RTS
;-------------------------------------------------------------------------------
;
; Sprite_SetFlag
; A - SPrite slot * 16
; X - bits to set...
;
;-------------------------------------------------------------------------------
Sprite_SetFlag:
STX SCRATCH1
CLC
ADC #SPRBLK_FLAG
TAX
LDA SprArray,X
ORA SCRATCH1
STA SPrArray,X
RTS
;-------------------------------------------------------------------------------
; TOTAL_SPRITE_SPACE = 8 * 15 sprites = 240 bytes
SPRArray: .byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
SPRActive:
.byte $ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff ; the eight active sprites ...
;-------------------------------------------------------------------------------
LookUp640:
.incbin "LookUpTable640"
SpriteData:
.incbin "Sprites"
;-------------------------------------------------------------------------------