RochesterX/nes
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Subpixels

Browse Source
This commit is contained in:
RochesterX
2026-02-18 15:04:42 -05:00
parent 0100b05291
commit 7a8fb73f84
2 changed files with 215 additions and 229 deletions
Download Patch File Download Diff File Expand all files Collapse all files

BIN
plat.nes
View File

Binary file not shown.

414
plat.s
View File

@@ -218,72 +218,6 @@ ppu_off:
rts
ppu_address_tile:
lda $2002
tya
lsr
lsr
lsr
ora #$20
sta $2006
tya
asl
asl
asl
asl
asl
sta temp
txa
ora temp
sta $2006
rts
ppu_update_tile:
pha
txa
pha
ldx nmt_update_len
tya
lsr
lsr
lsr
ora #$20
sta nmt_update, X
inx
tya
asl
asl
asl
asl
asl
sta temp
pla
ora temp
sta nmt_update, X
inx
pla
sta nmt_update, X
inx
stx nmt_update_len
rts
ppu_update_byte:
pha
tya
pha
ldy nmt_update_len
txa
sta nmt_update, Y
iny
pla
sta nmt_update, Y
iny
pla
sta nmt_update, Y
iny
sty nmt_update_len
rts
PAD_A = $01
PAD_B = $02
@@ -336,37 +270,32 @@ level:
.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 0,0,0,0,1,1,1,1,1,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,1,0,1,0,1,0
.byte 0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0
.byte 0,0,0,0,0,0,0,0,0,0,1,0,1,0,1,0
.byte 0,0,1,0,0,0,0,1,0,0,0,1,0,1,0,0
.byte 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
block_x: .res 1
block_y: .res 1
block_w: .res 1
block_h: .res 1
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,10,10,10,10,10
.byte 0,0,1,0,0,0,0,1,0,0,0,11,11,11,11,11
.byte 0,1,2,3,4,5,6,7,8,9,0,11,11,11,11,11
.byte 0,0,0,0,0,0,0,0,0,0,0,11,11,11,11,11
metatiles:
.byte 0,0,0,0,0
.byte $14,$15,$16,$17,1 ; Full block
.byte $14,$18,$1B,$0,1 ; up / left
.byte $18,$15,$0,$19,1 ; up / right
.byte $1B,$0,$16,$1A,1 ; down / left
.byte $0,$19,$1A,$17,1 ; down / right
.byte $1B,$0,$1B,$0,1 ; left
.byte $18,$18,$0,$0,1 ; up
.byte $0,$0,$1A,$1A,1 ; down
.byte $0,$19,$0,$19,1 ; right
.byte 3,3,3,3,0
.byte 3,4,5,6,0
.byte $14,$18,$1B,$00,0 ; up / left
.byte $18,$15,$00,$19,0 ; up / right
.byte $1B,$00,$16,$1A,0 ; down / left
.byte $00,$19,$1A,$17,0 ; down / right
.byte $1B,$00,$1B,$00,0 ; left
.byte $18,$18,$00,$00,0 ; up
.byte $00,$00,$1A,$1A,0 ; down
.byte $00,$19,$00,$19,0 ; right
.byte $10,$11,$12,$13,2
.byte $12,$12,$12,$12,2
example_palette:
.byte $0F,$00,$3D,$20 ; greyscale
.byte $0F,$3D,$30,$00 ; whitescale
.byte $0F,$09,$1A,$16 ; grass
.byte $0F,$15,$26,$37 ; bg0 purple/pink
.byte $0F,$09,$19,$29 ; bg1 green
.byte $0F,$2D,$10,$3D ; reboot bottom
.byte $0F,$2D,$10,$2C ; reboot eye
.byte $0F,$01,$11,$21 ; bg2 blue
@@ -381,11 +310,14 @@ buttons: .res 1
player_pos_x: .res 1
player_pos_y: .res 1
player_vel_x: .res 1
player_vel_y: .res 1
player_subpos_x: .res 1 ; XXXXYYYY | first 4 bits X subposition, last 4 bits Y
player_subpos_y: .res 1 ; XXXXYYYY | first 4 bits X subposition, last 4 bits Y
player_vel_x: .res 1 ; +PPPSSSS | first bit sign, next 3 pixels, last subpixels
player_vel_y: .res 1 ; in subpixels
player_status: .res 1 ; 76543210 | 0: facing (0 right, 1 left)
; | 7: talking
horizontal_speed: .res 1
cursor_x: .res 1
cursor_y: .res 1
@@ -424,17 +356,19 @@ main:
sta last_frame_jumped
jsr init_objects
@loop:
lda $2002
lda frame_counter
clc
adc #1
sta frame_counter
jsr controller
jsr movement
@draw:
jsr update_background
jsr draw_player
jsr ppu_update
@@ -543,13 +477,8 @@ init_objects:
sta player_vel_y
sta player_status
lda #64
sta block_x
sta block_y
lda #16
sta block_w
sta block_h
lda #32
sta horizontal_speed
rts
@@ -579,7 +508,7 @@ movement:
cmp #0
beq :+
ldx #1
lda #2
lda horizontal_speed
sta player_vel_x
lda player_status
@@ -591,7 +520,8 @@ movement:
cmp #0
beq :+
ldx #1
lda #254
lda horizontal_speed
ora #%10000000
sta player_vel_x
lda player_status
@@ -612,15 +542,17 @@ movement:
; If player_vel_x > 0, decrement
bpl :+
ldx player_vel_x
dex
lda player_vel_x
sec
sbc #16
stx player_vel_x
jmp @end
:
; Else if player_vel_x < 0, increment
ldx player_vel_x
inx
stx player_vel_x
lda player_vel_x
clc
adc #16
sta player_vel_x
@end:
; Jump
@@ -664,11 +596,84 @@ movement:
sta player_pos_y
; Apply X velocity
; Position
lda player_vel_x
and #%10000000
cmp #0
bne :+
; 0: right
lda player_vel_x
and #%01110000
clc
ror
clc
ror
clc
ror
clc
ror
sta var_n ; pixels
lda player_vel_x
and #%00001111
sta var_m ; subpixels
; A contains signed subpixels
clc
adc player_subpos_x ; add subposition and velocity subpixels
and #%00001111
cmp player_subpos_x ; if A (result) is less than current subpos, overflow occurred
bpl @end_add_subpos ; so skip if subpos is smaller than result
ldx player_pos_x
inx
stx player_pos_x
@end_add_subpos:
jmp :++
:
; 1: left
lda player_vel_x
and #%01110000
clc
ror
clc
ror
clc
ror
clc
ror
eor #%11111111
clc
adc #1
sta var_n ; pixels
lda player_vel_x
and #%00001111
eor #%00001111
clc
adc #1
and #%00001111
; A contains signed subpixels
clc
adc player_subpos_x ; add subposition and velocity subpixels
and #%00001111
cmp player_subpos_x ; if A (result) is greater than current subpos, underflow occurred
bmi @end_sub_subpos ; so skip if subpos is bigger than result
ldx player_pos_x
dex
stx player_pos_x
@end_sub_subpos:
:
lda player_pos_x
clc
adc player_vel_x
adc var_n ; add pixels
sta player_pos_x
; load x pos, filter blocks, check up and down
lda player_vel_y
@@ -708,23 +713,6 @@ movement:
rts
update_background:
rts
;lda $2002
;lda #$20
;sta $2006
;lda #$00
;sta $2006
ldx #1
ldy #1
jsr ppu_update_tile
lda #1
sta $2007
rts
setup_background:
lda $2002 ; reset latch
lda #$20
@@ -814,113 +802,111 @@ setup_background:
; clear attributes
;lda #0
;ldx #64 ; 64 bytes
;:
; lda #%11100100
;
; sta $2007
; dex
; bne :-
lda #0
ldx #64 ; 64 bytes
sta $50
ldy #0
:
lda #%11100100
tya
pha
sta $2007
dex
bne :-
rts
lda $2002 ; reset latch
lda #$20
sta $2006
lda #$00
sta $2006
; empty nametable
lda #0
ldy #30 ; 30 rows
:
ldx #32 ; 32 columns
:
sta $2007
dex
bne :-
dey
bne :--
; set all attributes to 0
lda #0
ldx #64 ; 64 bytes
ldx #0
:
tya
pha
txa
and #%00000011
pha
tya
asl
asl
asl
asl
sta temp
asl
sta temp_y
txa
and #%00000011
ora temp
lda #0
asl
clc
adc temp_y
tax
lda level, X
tay
lda #5
jsr mul_y
tay
lda metatiles+4, Y
sta temp_x
lda level+1, X
tay
lda #5
jsr mul_y
tay
lda metatiles+4, Y
asl
asl
adc temp_x
sta temp_x
lda level+16, X
tay
lda #5
jsr mul_y
tay
lda metatiles+4, Y
asl
asl
asl
asl
adc temp_x
sta temp_x
lda level+17, X
tay
lda #5
jsr mul_y
tay
lda metatiles+4, Y
asl
asl
asl
asl
asl
asl
adc temp_x
sta $2007
dex
bne :-
; fill in an area in the middle with 1/2 checkerboard
lda #1
ldy #0 ; start at row 8
:
pha ; temporarily store A, it will be clobbered by ppu_address_tile routine
ldx #8 ; start at column 8
jsr ppu_address_tile
pla ; recover A
ldx #8
:
sta $2007
eor #$3
ldx $50
inx
cpx #(32-8)
bcc :-
eor #$3
stx $50
sta $60, X
pla
tax
pla
tay
inx
cpx #8
bne :-
pla
tay
iny
cpy #(30-8)
bcc :--
lda #$24
sta $2006
lda #$00
sta $2006
lda #$00
ldy #30
:
ldx #32
:
sta $2007
clc
adc #1
and #3
dex
bne :-
clc
adc #1
and #3
dey
bne :--
lda #0
ldy #4
:
ldx #16
:
sta $2007
dex
bne :-
clc
adc #%01010101
dey
cpy #8
bne :--
rts