2010-03-10, 07:08 PM
Okay, reduced the flicker quite a bit more.
Sadly, because it's erase all four sprites and then redraws all sprites, different sprites start to flicker at different points.
If using 4 sprites:
Sprite 0 starts to flicker at above (pixel) line 10
And every other sprite at about 8 lines further down, per sprite.
If using 3 sprites
Sprites 0 is stable
Sprite 1 flickers above row 6
Sprite 3 starts to flicker at above line 16.
If using 2 sprites
Everything is stable.
I assume this is why the mojon's demonstrations only use 2 sprites...
I can't see any more speed optimizations (and right now it probably completes a redraw cycle in less than half the time of the original). There are probably some left, and no doubt Boriel will spot them immediately because he's a genius. However, right now I'm looking at changing /how/ it works. Things like not redrawing a sprite if it hasn't moved, and rather than erase all sprites and then draw all sprites, perhaps go for an erase-buffer-draw routine that does it on a per-sprite basis; limiting the time in which flicker can hit to areas of the screen.
The only alternative to that is to use a back-buffer screen; and that's a LOT of memory.
So right now, it's perfectly useable, if you think about where your sprites are going to go on the screen. The more sprites you have, the more careful you have to be - and keep the later numbered sprites away from the top of the screen!
So, here's how it stands right now (with a tweaked version of Apenao's demo program):
Sadly, because it's erase all four sprites and then redraws all sprites, different sprites start to flicker at different points.
If using 4 sprites:
Sprite 0 starts to flicker at above (pixel) line 10
And every other sprite at about 8 lines further down, per sprite.
If using 3 sprites
Sprites 0 is stable
Sprite 1 flickers above row 6
Sprite 3 starts to flicker at above line 16.
If using 2 sprites
Everything is stable.
I assume this is why the mojon's demonstrations only use 2 sprites...
I can't see any more speed optimizations (and right now it probably completes a redraw cycle in less than half the time of the original). There are probably some left, and no doubt Boriel will spot them immediately because he's a genius. However, right now I'm looking at changing /how/ it works. Things like not redrawing a sprite if it hasn't moved, and rather than erase all sprites and then draw all sprites, perhaps go for an erase-buffer-draw routine that does it on a per-sprite basis; limiting the time in which flicker can hit to areas of the screen.
The only alternative to that is to use a back-buffer screen; and that's a LOT of memory.
So right now, it's perfectly useable, if you think about where your sprites are going to go on the screen. The more sprites you have, the more careful you have to be - and keep the later numbered sprites away from the top of the screen!
So, here's how it stands right now (with a tweaked version of Apenao's demo program):
Code:
#DEFINE BLACK 0
#DEFINE BLUE 1
#DEFINE RED 2
#DEFINE MAGENTA 3
#DEFINE GREEN 4
#DEFINE CYAN 5
#DEFINE YELLOW 6
#DEFINE WHITE 7
#DEFINE TRANSPARENT 8
#DEFINE CONTRAST 9
#DEFINE TRUE 1
#DEFINE FALSE 0
SUB fspInitialize (n as uByte, udgA as uByte, udgB as uByte, udgC as uByte, udgD as uByte,x as uByte,y as uByte) 'Initialize Sprite: n (sprite number 0-3);a,b,c,d (UDG number 0-20,99 means the sprite won't be printed)
#ifndef FINAL_CODE
IF n>3 OR (udgA>20 AND udgA<>99) or udgB>20 or udgC>20 or udgD>20 then Print "Out Of Bounds Call in ";"fspInitialize" : stop : END IF : REM Bounds checking - so a bad function call doesn't poke all over memory.
#endif
DIM targetAddr as uInteger
targetAddr=@fspDataStart+(48*n)
fspErase()
POKE targetAddr,udgA
targetAddr=targetAddr+1
POKE targetAddr,udgB
targetAddr=targetAddr+1
POKE targetAddr,udgC
targetAddr=targetAddr+1
POKE targetAddr,udgD
targetAddr=targetAddr+1
POKE targetAddr,x
targetAddr=targetAddr+1
POKE targetAddr,y
targetAddr=targetAddr+1
POKE targetAddr,x
targetAddr=targetAddr+1
POKE targetAddr,y
fspBufferAndDraw()
RETURN
fspDataStart:
REM This Section contains Fourspriter data and code that is called by other routines.
ASM
;; 16x16 Sprites moving a character each frame
;; Copyleft 2009 The Mojon Twins.
;; Updated Copyleft 2010 Paul Fisher
;; Uses UDGs (it reads the address from the system variables).
;; It moves up to 4 sprites, preserving the backgrounds.
;; Sprite control is done writing a certain number
;; in the Sprite's first UDG
;; If the first UDG is 99, it won't be printed
; Note that the sprites are initialized to disabled.
fspDataStartAsm: ; each block is 48 bytes long. [This comment originally said 40 bytes, and it's clearly 48]
;; Sprite 1
udgs1: defb 99,0,0,0 ; Four UDGs of the first sprite.
x_pos1: defb 0 ; X position in chars.
y_pos1: defb 0 ; Y position in chars.
cx_pos1: defb 0 ; Previous X position in chars.
cy_pos1: defb 0 ; Previous Y position in chars.
buffer1: defb 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ; Background Gfx buffer.
attrs1: defb 6,7,7,7 ; Sprite ATTRs
buffatrs1: defb 0,0,0,0 ; Background Attr's buffer
;; Sprite 2
udgs2: defb 99,0,0,0
x_pos2: defb 0
y_pos2: defb 0
cx_pos2: defb 0
cy_pos2: defb 0
buffer2: defb 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
attrs2: defb 7,7,7,7
buffatrs2: defb 0,0,0,0
;; Sprite 3
udgs3: defb 99,0,0,0
x_pos3: defb 0
y_pos3: defb 0
cx_pos3: defb 0
cy_pos3: defb 0
buffer3: defb 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
attrs3: defb 7,7,7,7
buffatrs3: defb 0,0,0,0
;; Sprite 4
udgs4: defb 99,0,0,0
x_pos4: defb 0
y_pos4: defb 0
cx_pos4: defb 0
cy_pos4: defb 0
buffer4: defb 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
attrs4: defb 7,7,7,7
buffatrs4: defb 0,0,0,0
fspCollisionDetect: defb 0,0,0 ; Sprite 0 with 1,2,3
defb 0,0 ; Sprite 1 with 2,3
defb 0 ; sprite 2 with 3
fspCopyToScreen:
call get_scr_address ; Returns (xpos, ypos) in HL
ld a, (de)
ld (hl), a
inc h
inc de
ld a, (de)
ld (hl), a
inc h
inc de
ld a, (de)
ld (hl), a
inc h
inc de
ld a, (de)
ld (hl), a
inc h
inc de
ld a, (de)
ld (hl), a
inc h
inc de
ld a, (de)
ld (hl), a
inc h
inc de
ld a, (de)
ld (hl), a
inc h
inc de
ld a, (de)
ld (hl), a
inc h
inc de
ret
fspCopyFromScreen:
call get_scr_address
ld a, (hl)
ld (de), a
inc h
inc de
ld a, (hl)
ld (de), a
inc h
inc de
ld a, (hl)
ld (de), a
inc h
inc de
ld a, (hl)
ld (de), a
inc h
inc de
ld a, (hl)
ld (de), a
inc h
inc de
ld a, (hl)
ld (de), a
inc h
inc de
ld a, (hl)
ld (de), a
inc h
inc de
ld a, (hl)
ld (de), a
inc h
inc de
ret
; This function returns the address into HL of the screen address
; b,c in character grid notation.
; Original code was extracted by BloodBaz
get_scr_address:
push de
ld a,b ; b=x
and 31
ld l,a
ld a,c ; c=y
ld d,a
and 24
add a,64
ld h,a
ld a,d
and 7
rrca
rrca
rrca
or l
ld l,a
pop de
ret
;; This function returns the memory address of the Character Position
;; b,c in the attribute screen memory.
;; Adapted from code by Jonathan Cauldwell.
get_attr_address:
ld a,c ;ypos
rrca
rrca
rrca ; Multiply by 32
ld l,a ; Pass to L
and 3 ; Mask with 00000011
add a,88 ; 88 * 256 = 22528 - start of attributes.
ld h,a ; Put it in the High Byte
ld a,l ; We get y value *32
and 224 ; Mask with 11100000
ld l,a ; Put it in L
ld a,b ; xpos
add a,l ; Add it to the Low byte
ld l,a ; Put it back in L, and we're done. HL=Address.
ret
;; Routine to save the background to the buffer
fspEraseAsm:
ld hl, fspDataStartAsm
EXX
ld b, 4
i4chars2:
EXX
;;
ld a, (hl)
cp 99
jr z, nxt2
;; A
LD BC,6
;EX DE,HL ; HL now points at the start sprite data instead
ADD HL,BC ; HL moved on to point to old x-y positions.
LD b,(HL) ; b=x
INC HL
LD c,(HL) ;c=y
INC HL
EX DE,HL ; Now it's DE that points into the data buffer.
; Draw first background character
call fspCopyToScreen
;; B
; xpos++
inc b
; Draw second background Character
call fspCopyToScreen
;; C
; xpos --
dec b
; ypos ++
inc c
; draw Third background Character
call fspCopyToScreen
;; D
; xpos++
inc b
; Draw Fourth background Character
call fspCopyToScreen
;; move to attr
inc de
inc de
inc de
inc de
;Set our position to top left corner again
; xpos --
dec b
; ypos --
dec c
call get_attr_address
EX DE,HL
;copyattrs
ld bc, 32
;First
LDI
;Second
LDI
; DE=DE+BC
EX DE,HL
add hl,bc
EX DE,HL
;Third
LDI
;Fourth
LDI
nxt2: EXX
djnz i4chars2
ret
fspBufferAndDrawAsm:
ld hl, fspDataStartAsm
EXX
ld b, 4
i4chars:
;push bc
EXX
;Active Sprite?
ld a, (hl)
cp 99
jr z, nxt1
;; A
LD BC,4
ADD HL,BC ; move past the udg part
;xpos
ld b,(hl)
inc hl
;ypos
ld c,(hl)
inc hl
inc hl ; move past the old co-ordinates
inc hl
EX de,hl
call fspCopyFromScreen
;; B
; xpos++
;ld hl, xpos
;inc (hl)
inc b
call fspCopyFromScreen
;; C
; xpos --
;ld hl, xpos
;dec (hl)
dec b
; ypos ++
;ld hl, ypos
;inc (hl)
inc c
call fspCopyFromScreen
;; D
; xpos++
;ld hl, xpos
;inc (hl)
inc b
call fspCopyFromScreen
;; Now we point to the ATTR buffer,adding 4:
inc de
inc de
inc de
inc de
;Put ourselves back at the top left corner.
; xpos --
dec b
; ypos --
dec c
call get_attr_address
ld bc, 32
;First Character
LDI ; bc was loaded with 32 instead of 31 to account for the BC-- this instruction has.
;Second Character
LDI
add hl, bc ; we can get away with this because BC++ as well as hl--
;Third Character
LDI
;Fourth Character
LDI
EX DE,HL ; back to an HL pointer.
nxt1: EXX
djnz i4chars
; Go straight into Painting new sprites for speed.
;; Print sprites routine
;; UDGs are labeled from 0 to 21. The addres of the UDG is:
;; *(23675) + 256 * *(23676) + 8 * N
fspDrawAsm:
ld hl, fspDataStartAsm ;
EXX
ld b, 4 ;
i4chars3:
;push bc
EXX
ld a, (hl)
cp 99
jr z, nxt3
;; Copy pointer "HL" to alt reg
push HL
exx
pop HL
exx
ld bc,4
add hl,bc
; Get xpos
LD b,(hl) ;x
inc hl
; Get ypos
ld c,(hl) ;y
inc hl
push HL ; de Save pointer.
EXX
LD A,(HL)
INC HL
EXX
call fspGetUdgAddr
;Draw the first character
call fspCopyToScreen
; xpos++
inc b
; Address of the graphics
EXX
LD A,(HL)
INC HL
EXX
call fspGetUdgAddr
; Draw the second Character
call fspCopyToScreen
; xpos--
dec b
; ypos ++
inc c
; Address of Graphics
EXX
LD A,(HL)
INC HL
EXX
call fspGetUdgAddr
; Draw the third character
call fspCopyToScreen
; xpos ++
inc b
; Address of next Graphic
EXX
LD A,(HL)
INC HL
EXX
call fspGetUdgAddr
; Draw the fourth Character
call fspCopyToScreen
pop hl ; Recover hl to point at the start of the pixel buffer
; hl = hl + 32
ld a,l
add a,34
ld l,a
jp nc, fspNoIncH
inc h ; hl now points to the attr data.
fspNoIncH:
EX DE,HL
;Reset position to top left.
; xpos --
dec b
; ypos --
dec c
;; attr
call get_attr_address
EX DE,HL
;copyattrs
ld bc, 32
;First
LDI
;Second
LDI
; DE=DE+BC
EX DE,HL
add hl,bc
EX DE,HL
;Third
LDI
;Fourth
LDI
LD BC,4
ADD HL,BC ; Move pointer to start of next block
nxt3: EXX
djnz i4chars3
ret
fspGetUdgAddr:
; finds the address of the UDG # in A
ld HL,(23675) ;HL points to the UDG space
rlca
rlca
rlca ; a = N * 8
ld d, 0
ld e, a
add hl, de
EX DE,HL
ret
fspUpdateAsm: ; This name will be used from ASM
; For each Sprite:
;; *(data + 6) = *(data + 4)
;; *(data + 7) = *(data + 5)
ld hl, fspDataStartAsm+4 ; Points to sprite 1
ld de, fspDataStartAsm+6
ldi
ldi
ld hl, fspDataStartAsm+4+48 ; Points to sprite 2
ld de, fspDataStartAsm+6+48
ldi
ldi
ld hl, fspDataStartAsm+4+48+48 ; Points to sprite 3
ld de, fspDataStartAsm+6+48+48
ldi
ldi
ld hl, fspDataStartAsm+4+48+48+48 ; Points to sprite 4
ld de, fspDataStartAsm+6+48+48+48
ldi
ldi
ret
END ASM
END SUB
SUB fspDisable (n as UByte)
#ifndef FINAL_CODE
IF n>3 then Print "Out Of Bounds Call in ";"fspDisable" : stop: END IF
#endif
fspErase()
POKE @fspDataStart+48*n,99
end SUB
SUB fspCoord (n as uByte, x as uByte, y as uByte) 'Set sprite coords: n (sprite number);x,y (vertical,horizontal coords)
#ifndef FINAL_CODE
IF n>3 then Print "Out Of Bounds Call in ";"fspCoord" : stop: END IF
#endif
DIM targetAddr as uInteger
targetAddr=@fspDataStart+4+48*n
POKE targetAddr,x
targetAddr=targetAddr+1
POKE targetAddr,y
rem targetAddr=targetAddr+1
rem POKE targetAddr,x
rem targetAddr=targetAddr+1
rem POKE targetAddr,y
END SUB
SUB fspAttrs (n as uByte, attra as uByte, attrb as uByte, attrc as uByte, attrd as uByte) 'Set sprite attrs: n (sprite number);a,b,c,d (UDG attrs)
#ifndef FINAL_CODE
IF n>3 then Print "Out Of Bounds Call in ";"fspAttrs" : stop: END IF
#endif
DIM targetAddr as uInteger
targetAddr=@fspDataStart+40+48*n
POKE targetAddr,attra
targetAddr=targetAddr+1
POKE targetAddr,attrb
targetAddr=targetAddr+1
POKE targetAddr,attrc
targetAddr=targetAddr+1
POKE targetAddr,attrd
END SUB
FUNCTION fspAttrByte(fspInk as uByte,fspPaper as uByte,fspBright as uByte, fspFlash as uByte) as uByte
#ifndef FINAL_CODE
if fspInk > 7 OR fspPaper > 7 OR fspBright > 1 or fspFlash >1 then Print "Out Of Bounds Call in ";"fspAttrByte" : stop: END IF
#endif
return (fspFlash shl 7) + (fspBright shl 6) + (fspPaper shl 3) + fspInk
END FUNCTION
SUB fspAttr(n as uByte,fspInk as uByte,fspPaper as uByte,fspBright as uByte, fspFlash as uByte)
#ifndef FINAL_CODE
if fspInk > 7 OR fspPaper > 7 OR fspBright > 1 or fspFlash >1 then Print "Out Of Bounds Call in ";"fspAttr" : stop: END IF
#endif
DIM attrByte as uByte
attrByte=fspAttrByte(fspInk,fspPaper,fspBright,fspFlash)
fspAttrs(n,attrByte,attrByte,attrByte,attrByte)
END SUB
SUB FASTCALL fspErase()
asm
call fspEraseAsm
end asm
END SUB
SUB FASTCALL fspBufferAndDraw()
asm
call fspBufferAndDrawAsm
end asm
END SUB
SUB FASTCALL fspUpdate()
asm
call fspUpdateAsm
END ASM
END SUB
SUB fspRedraw()
asm
halt
;REM Erase the sprites
call fspEraseAsm
;REM Save background and
;REM print sprites
call fspBufferAndDrawAsm
;REM update coordinates
call fspUpdateAsm
end asm
END SUB
REM below this is Apenao's Demo Program:
#include <sinclair.bas>
#include <memcopy.bas>
#include <keys.bas>
100 DIM gentle (0 to 3,0 to 7) AS uByte => { { 15, 15, 15, 15, 15, 15, 13, 15} , _
{ 240, 144, 208, 208, 240, 240, 176, 240} , _
{ 15, 14, 63, 0, 0, 12, 26, 30} , _
{ 176, 112, 252, 0, 0, 48, 104, 120}}
110 POKE Uinteger 23675, @gentle(0,0)
CLS
for n = 0 to 15
print paper (n mod 7); ink ((n+3) mod 8); "ABCDEFGHIJKLMNOPQRSTUVWXYZ123456"
next n
let cx=1:let cy=1: let cmx=1:let cmy=1
let dx=7:let dy=5: let dmx=1:let dmy=-1
let tx=10:let ty=7: let tmx=-1:let tmy=1
LET gx=15:LET gy=11
fspInitialize (0,0,1,2,3,gx,gy) : REM (sprite number, udgA, udgB,udgC,udgD, initial X co-ordinate, initial y-coordinate)
fspInitialize (1,0,1,2,3,dx,dy)
fspInitialize (2,0,1,2,3,tx,ty)
fspInitialize (3,0,1,2,3,cx,cy)
fspAttr(0,WHITE,MAGENTA,FALSE,FALSE) : REM (sprite number, ink, paper, bright, flash)
fspAttr(1,YELLOW,BLACK,FALSE,FALSE)
fspAttr(2,GREEN,BLUE,TRUE,FALSE)
fspAttr(3,RED,WHITE,FALSE,FALSE)
DO
pause 2
IF MULTIKEYS(KEYO) and gx>0 THEN LET gx=gx-1: END IF
IF MULTIKEYS(KEYP) and gx<30 THEN LET gx=gx+1:END IF
IF MULTIKEYS(KEYQ) and gy>0 THEN LET gy=gy-1 :END IF
IF MULTIKEYS(KEYA) and gy<22 THEN LET gy=gy+1: END IF
let dx=dx+dmx:if dx=1 or dx=30 then let dmx=-dmx : END IF
let dy=dy+dmy:if dy=0 or dy=22 then let dmy=-dmy: END IF
let tx=tx+tmx:if tx=0 or tx=30 then let tmx=-tmx: END IF
let ty=ty+tmy:if ty=0 or ty=22 then let tmy=-tmy: END IF
let cx=cx+cmx:if cx=0 or cx=30 then let cmx=-cmx: END IF
let cy=cy+cmy:if cy=0 or cy=22 then let cmy=-cmy: END IF
fspCoord (0,gx,gy)
fspCoord (1,dx,dy)
fspCoord (2,tx,ty)
fspCoord (3,cx,cy)
fspRedraw()
loop