mirror of
https://github.com/lscharen/iigs-game-engine.git
synced 2024-11-23 03:33:11 +00:00
460 lines
14 KiB
ArmAsm
460 lines
14 KiB
ArmAsm
; An overlay is a callback from the render to shadow in a range of lines. At a minimum, the overlay
|
|
; code needs to LDA/STA or TSB slam the data, but an overlay is typically used to draw some graphic
|
|
; on top of the rendered playfield, such as a status bar or in-game message
|
|
;
|
|
; This overlay implementation is for a status bar that is 8-lines height that will be used to display some
|
|
; status information. The interesting bit of this implementation is that it's split into two pieces,
|
|
; a left and right section in order to be able to use the same code for different screen widths, but
|
|
; still keep the content in the cornders while covering the full screen.
|
|
;
|
|
; There are two subroutines that need to be implemented -- one to update the overlay content and a
|
|
; second to actually render to the screen
|
|
|
|
STATE_REG equ $E0C068
|
|
|
|
_R0W0 mac ; Read Bank 0 / Write Bank 0
|
|
sep #$20
|
|
ldal STATE_REG
|
|
and #$CF
|
|
stal STATE_REG
|
|
rep #$20
|
|
<<<
|
|
|
|
_R0W1 mac ; Read Bank 0 / Write Bank 1
|
|
sep #$20
|
|
ldal STATE_REG
|
|
ora #$10
|
|
stal STATE_REG
|
|
rep #$20
|
|
<<<
|
|
|
|
_R1W1 mac ; Read Bank 1 / Write Bank 1
|
|
sep #$20
|
|
ldal STATE_REG
|
|
ora #$30
|
|
stal STATE_REG
|
|
rep #$20
|
|
<<<
|
|
|
|
; Initialize the overlay be drawing in static content that will not change over time
|
|
|
|
; Define the sizes of the left and right overlay buffers
|
|
R_CHAR_COUNT equ 8 ; "TICK:XXX"
|
|
L_CHAR_COUNT equ 7 ; "FPS:XXX"
|
|
|
|
; Allocate a single buffer for holding both the left and right overlay characters + masks
|
|
CHAR_WIDTH equ 4
|
|
OVRLY_SPAN equ {{L_CHAR_COUNT+R_CHAR_COUNT}*CHAR_WIDTH}
|
|
|
|
ovrly_buff ds OVRLY_SPAN*8
|
|
ovrly_mask ds OVRLY_SPAN*8
|
|
|
|
r_line equ ovrly_buff+{L_CHAR_COUNT*CHAR_WIDTH}
|
|
l_line equ ovrly_buff
|
|
r_mask equ ovrly_mask+{L_CHAR_COUNT*CHAR_WIDTH}
|
|
l_mask equ ovrly_mask
|
|
|
|
MASK_OFFSET equ {ovrly_mask-ovrly_buff}
|
|
|
|
TileDataPtr equ $FC
|
|
TileMaskPtr equ $F8
|
|
|
|
; set this to the real tile id that starts an ASCII run starting at '0' through 'Z'
|
|
CHAR_TILE_BASE equ $F6
|
|
|
|
InitOverlay
|
|
sta CHAR_TILE_BASE
|
|
pha
|
|
pha
|
|
_GTEGetTileDataAddr
|
|
pla
|
|
sta TileDataPtr
|
|
clc
|
|
adc #32
|
|
sta TileMaskPtr
|
|
pla
|
|
sta TileDataPtr+2
|
|
sta TileMaskPtr+2
|
|
|
|
lda #'F'
|
|
ldx #l_line+{CHAR_WIDTH*0}
|
|
jsr _DrawChar
|
|
lda #'P'
|
|
ldx #l_line+{CHAR_WIDTH*1}
|
|
jsr _DrawChar
|
|
lda #'S'
|
|
ldx #l_line+{CHAR_WIDTH*2}
|
|
jsr _DrawChar
|
|
lda #':'
|
|
ldx #l_line+{CHAR_WIDTH*3}
|
|
jsr _DrawChar
|
|
|
|
lda #'T'
|
|
ldx #r_line+{CHAR_WIDTH*0}
|
|
jsr _DrawChar
|
|
lda #'I'
|
|
ldx #r_line+{CHAR_WIDTH*1}
|
|
jsr _DrawChar
|
|
lda #'C'
|
|
ldx #r_line+{CHAR_WIDTH*2}
|
|
jsr _DrawChar
|
|
lda #'K'
|
|
ldx #r_line+{CHAR_WIDTH*3}
|
|
jsr _DrawChar
|
|
lda #':'
|
|
ldx #r_line+{CHAR_WIDTH*4}
|
|
jsr _DrawChar
|
|
|
|
pea $0000 ; logical lines for the overlay bar
|
|
pea $0008
|
|
pea #^StatusBar
|
|
pea #StatusBar
|
|
_GTESetOverlay
|
|
rts
|
|
|
|
; Update the dynamic content of the overlay
|
|
_num2ascii
|
|
and #$000F
|
|
cmp #$000A
|
|
bcc :out
|
|
clc
|
|
adc #'A'-'0'-10
|
|
|
|
:out clc
|
|
adc #'0'
|
|
rts
|
|
|
|
UdtOverlay
|
|
lda frameCount ; render the FPS value
|
|
xba
|
|
jsr _num2ascii
|
|
ldx #l_line+{CHAR_WIDTH*4}
|
|
jsr _DrawChar
|
|
|
|
lda frameCount
|
|
lsr
|
|
lsr
|
|
lsr
|
|
lsr
|
|
jsr _num2ascii
|
|
ldx #l_line+{CHAR_WIDTH*5}
|
|
jsr _DrawChar
|
|
|
|
lda frameCount
|
|
jsr _num2ascii
|
|
ldx #l_line+{CHAR_WIDTH*6}
|
|
jsr _DrawChar
|
|
|
|
pha
|
|
_GTEGetSeconds
|
|
pla
|
|
sta oneSecondCounter ; render the number of remaining seconds
|
|
xba
|
|
jsr _num2ascii
|
|
ldx #r_line+{CHAR_WIDTH*5}
|
|
jsr _DrawChar
|
|
|
|
lda oneSecondCounter
|
|
lsr
|
|
lsr
|
|
lsr
|
|
lsr
|
|
jsr _num2ascii
|
|
ldx #r_line+{CHAR_WIDTH*6}
|
|
jsr _DrawChar
|
|
|
|
lda oneSecondCounter
|
|
jsr _num2ascii
|
|
ldx #r_line+{CHAR_WIDTH*7}
|
|
jsr _DrawChar
|
|
|
|
rts
|
|
|
|
oneSecondCounter ds 2
|
|
|
|
; Draw the overlay
|
|
; A = address of the left edge of the screen
|
|
; X = top line to start drawing the overlay (typically 0)
|
|
; Y = bottom line to stop drawing the overlayer (typically the overlay height set during call to _SetOverlay)
|
|
StatusBar phb ; Called via JSL
|
|
phd ; save the direct page register
|
|
|
|
phk
|
|
plb
|
|
|
|
ldx MyDirectPage ; Preserve the accumulator
|
|
phx
|
|
pld
|
|
|
|
sta l_addr ; save this value (will go into D-reg later)
|
|
clc
|
|
adc #L_CHAR_COUNT*CHAR_WIDTH ; advance past the left characters
|
|
sta m_addr ; this is the DP for the TSB slam
|
|
|
|
lda l_addr
|
|
clc
|
|
adc ScreenWidth
|
|
sec
|
|
sbc #{R_CHAR_COUNT*CHAR_WIDTH}
|
|
sta r_addr ; this is the DP for the right side
|
|
|
|
; Calculate the TSB slam entry point
|
|
|
|
sec
|
|
sbc m_addr ; calculate the number of words between the two ends
|
|
and #$FFFE
|
|
|
|
eor #$FFFF
|
|
inc
|
|
clc
|
|
adc #m_end
|
|
sta m_patch+1
|
|
|
|
sei
|
|
_R1W1
|
|
|
|
ldy #8 ; count the line we're on
|
|
ldx #0
|
|
ovrly_loop
|
|
lda r_addr
|
|
tcd ; set the direct page for the right side
|
|
jmp r_ovrly ; render that line
|
|
r_ovrly_rtn
|
|
|
|
lda m_addr
|
|
tcd ; set the direct page for the slam in the middle
|
|
lda #0 ; set to zero for TSB slam
|
|
m_patch jmp $0000 ; jump into the slam field
|
|
m_ovrly_rtn
|
|
|
|
lda l_addr ; set the direct page for the left side
|
|
tcd
|
|
jmp l_ovrly
|
|
l_ovrly_rtn
|
|
clc
|
|
tdc
|
|
adc #160 ; advance to the next screen line
|
|
sta l_addr
|
|
adc #{L_CHAR_COUNT*CHAR_WIDTH}
|
|
sta m_addr
|
|
lda r_addr
|
|
adc #160
|
|
sta r_addr
|
|
|
|
txa
|
|
adc #OVRLY_SPAN
|
|
tax
|
|
|
|
dey
|
|
bne ovrly_loop
|
|
|
|
_R0W0
|
|
cli
|
|
|
|
o_exit
|
|
pld ; restore the direct page and bank and return
|
|
plb
|
|
rtl
|
|
|
|
l_addr ds 2
|
|
m_addr ds 2
|
|
r_addr ds 2
|
|
|
|
r_ovrly
|
|
]idx equ 0
|
|
lup R_CHAR_COUNT
|
|
lda ]idx
|
|
and r_line+MASK_OFFSET+]idx,x
|
|
ora r_line+]idx,x
|
|
sta ]idx
|
|
lda ]idx+2
|
|
and r_line+MASK_OFFSET+]idx+2,x
|
|
ora r_line+]idx+2,x
|
|
sta ]idx+2
|
|
]idx equ ]idx+4
|
|
--^
|
|
jmp r_ovrly_rtn ; In R1W1, so can't use the stack
|
|
|
|
r_ovrly2
|
|
]idx equ 0
|
|
lup R_CHAR_COUNT
|
|
lda r_line+]idx,x
|
|
sta ]idx
|
|
lda r_line+]idx+2,x
|
|
sta ]idx+2
|
|
]idx equ ]idx+4
|
|
--^
|
|
jmp r_ovrly_rtn ; In R1W1, so can't use the stack
|
|
|
|
l_ovrly
|
|
]idx equ 0
|
|
lup L_CHAR_COUNT
|
|
lda ]idx
|
|
and l_line+MASK_OFFSET+]idx,x
|
|
ora l_line+]idx,x
|
|
sta ]idx
|
|
lda ]idx+2
|
|
and l_line+MASK_OFFSET+]idx+2,x
|
|
ora l_line+]idx+2,x
|
|
sta ]idx+2
|
|
]idx equ ]idx+4
|
|
--^
|
|
jmp l_ovrly_rtn
|
|
|
|
l_ovrly2
|
|
]idx equ 0
|
|
lup L_CHAR_COUNT
|
|
lda l_line+]idx,x
|
|
sta ]idx
|
|
lda l_line+]idx+2,x
|
|
sta ]idx+2
|
|
]idx equ ]idx+4
|
|
--^
|
|
jmp l_ovrly_rtn
|
|
|
|
; Single TSB slam
|
|
m_line
|
|
]idx equ $9E
|
|
lup 80 ; 80 words max for a full-width screen
|
|
; sta ]idx
|
|
tsb ]idx
|
|
]idx equ ]idx-2
|
|
--^
|
|
m_end
|
|
jmp m_ovrly_rtn
|
|
|
|
|
|
; Draw a character (tile) into a location of the overlay
|
|
;
|
|
; A = Tile ID
|
|
; Y = overlay address location
|
|
_DCOut rts
|
|
_DrawChar
|
|
cmp #'0'
|
|
bcc _DCOut
|
|
cmp #'Z'+1
|
|
bcs _DCOut
|
|
|
|
sec
|
|
sbc #'0'
|
|
clc
|
|
adc CHAR_TILE_BASE
|
|
jsr _GetTileAddr
|
|
tay
|
|
|
|
lda [TileMaskPtr],y
|
|
sta: {0*OVRLY_SPAN}+MASK_OFFSET,x
|
|
lda [TileDataPtr],y
|
|
sta: {0*OVRLY_SPAN},x
|
|
iny
|
|
iny
|
|
lda [TileMaskPtr],y
|
|
sta: {0*OVRLY_SPAN}+MASK_OFFSET+2,x
|
|
lda [TileDataPtr],y
|
|
sta: {0*OVRLY_SPAN}+2,x
|
|
iny
|
|
iny
|
|
|
|
lda [TileMaskPtr],y
|
|
sta: {1*OVRLY_SPAN}+MASK_OFFSET,x
|
|
lda [TileDataPtr],y
|
|
sta: {1*OVRLY_SPAN},x
|
|
iny
|
|
iny
|
|
lda [TileMaskPtr],y
|
|
sta: {1*OVRLY_SPAN}+MASK_OFFSET+2,x
|
|
lda [TileDataPtr],y
|
|
sta: {1*OVRLY_SPAN}+2,x
|
|
iny
|
|
iny
|
|
|
|
lda [TileMaskPtr],y
|
|
sta: {2*OVRLY_SPAN}+MASK_OFFSET,x
|
|
lda [TileDataPtr],y
|
|
sta: {2*OVRLY_SPAN},x
|
|
iny
|
|
iny
|
|
lda [TileMaskPtr],y
|
|
sta: {2*OVRLY_SPAN}+MASK_OFFSET+2,x
|
|
lda [TileDataPtr],y
|
|
sta: {2*OVRLY_SPAN}+2,x
|
|
iny
|
|
iny
|
|
|
|
lda [TileMaskPtr],y
|
|
sta: {3*OVRLY_SPAN}+MASK_OFFSET,x
|
|
lda [TileDataPtr],y
|
|
sta: {3*OVRLY_SPAN},x
|
|
iny
|
|
iny
|
|
lda [TileMaskPtr],y
|
|
sta: {3*OVRLY_SPAN}+MASK_OFFSET+2,x
|
|
lda [TileDataPtr],y
|
|
sta: {3*OVRLY_SPAN}+2,x
|
|
iny
|
|
iny
|
|
|
|
lda [TileMaskPtr],y
|
|
sta: {4*OVRLY_SPAN}+MASK_OFFSET,x
|
|
lda [TileDataPtr],y
|
|
sta: {4*OVRLY_SPAN},x
|
|
iny
|
|
iny
|
|
lda [TileMaskPtr],y
|
|
sta: {4*OVRLY_SPAN}+MASK_OFFSET+2,x
|
|
lda [TileDataPtr],y
|
|
sta: {4*OVRLY_SPAN}+2,x
|
|
iny
|
|
iny
|
|
|
|
lda [TileMaskPtr],y
|
|
sta: {5*OVRLY_SPAN}+MASK_OFFSET,x
|
|
lda [TileDataPtr],y
|
|
sta: {5*OVRLY_SPAN},x
|
|
iny
|
|
iny
|
|
lda [TileMaskPtr],y
|
|
sta: {5*OVRLY_SPAN}+MASK_OFFSET+2,x
|
|
lda [TileDataPtr],y
|
|
sta: {5*OVRLY_SPAN}+2,x
|
|
iny
|
|
iny
|
|
|
|
lda [TileMaskPtr],y
|
|
sta: {6*OVRLY_SPAN}+MASK_OFFSET,x
|
|
lda [TileDataPtr],y
|
|
sta: {6*OVRLY_SPAN},x
|
|
iny
|
|
iny
|
|
lda [TileMaskPtr],y
|
|
sta: {6*OVRLY_SPAN}+MASK_OFFSET+2,x
|
|
lda [TileDataPtr],y
|
|
sta: {6*OVRLY_SPAN}+2,x
|
|
iny
|
|
iny
|
|
|
|
lda [TileMaskPtr],y
|
|
sta: {7*OVRLY_SPAN}+MASK_OFFSET,x
|
|
lda [TileDataPtr],y
|
|
sta: {7*OVRLY_SPAN},x
|
|
iny
|
|
iny
|
|
lda [TileMaskPtr],y
|
|
sta: {7*OVRLY_SPAN}+MASK_OFFSET+2,x
|
|
lda [TileDataPtr],y
|
|
sta: {7*OVRLY_SPAN}+2,x
|
|
|
|
rts
|
|
|
|
_GetTileAddr
|
|
asl ; Multiply by 2
|
|
bit #2*TILE_HFLIP_BIT ; Check if the horizontal flip bit is set
|
|
beq :no_flip
|
|
inc ; Set the LSB
|
|
:no_flip asl ; x4
|
|
asl ; x8
|
|
asl ; x16
|
|
asl ; x32
|
|
asl ; x64
|
|
asl ; x128
|
|
rts |