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road fix

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This commit is contained in:
mr.zero
2026-07-16 15:53:33 +02:00
parent df991b0e09
commit 850c461d32
6 changed files with 105 additions and 17 deletions
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common.asm
+72 -10
View File
@@ -60,6 +60,68 @@ row_ptr:
sta colhi
rts
; ---- charset_init: copy the ROM charset into RAM and patch
; in the custom road / tree glyphs (multicolor bit pairs, see
; defs.asm); runs once at boot ----
charset_init:
lda #$33 ; char ROM in at $d000 (IO banked out)
sta $01
lda #0
sta scrlo
sta collo
lda #$d0
sta scrhi
lda #>CHSET
sta colhi
ldx #8 ; the full 2K uppercase/graphics set
ldy #0
chs_copy:
lda (scrlo),y
sta (collo),y
iny
bne chs_copy
inc scrhi
inc colhi
dex
bne chs_copy
lda #$37 ; IO back in
sta $01
ldx #7 ; overlay the five custom glyphs
chs_patch:
lda gl_edgel,x
sta CHSET+CH_EDGEL*8,x
lda gl_edger,x
sta CHSET+CH_EDGER*8,x
lda gl_road,x
sta CHSET+CH_ROADF*8,x
lda gl_leaf,x
sta CHSET+CH_LEAF*8,x
lda gl_trunk,x
sta CHSET+CH_TRUNK*8,x
dex
bpl chs_patch
lda #$1e ; VIC: screen at $0400, charset at CHSET
sta VMEM
lda #COL_LEAF
sta CHAR_MC1
lda #COL_ROAD
sta CHAR_MC2
rts
; the custom glyphs: 4 double-wide pixels per row as 2-bit
; pairs (%00 background, %01 CHAR_MC1, %10 CHAR_MC2, %11 the
; cell's color RAM bits 0-2)
gl_edgel: ; grass | white line \ road grey
!byte $03, $03, $0e, $0e, $3a, $3a, $ea, $ea
gl_edger: ; road grey / white line | grass
!byte $c0, $c0, $b0, $b0, $ac, $ac, $ab, $ab
gl_road: ; solid road surface: all %10 pairs
!byte $aa, $aa, $aa, $aa, $aa, $aa, $aa, $aa
gl_leaf: ; foliage ball: %01 pairs
!byte $14, $55, $55, $55, $55, $55, $14, $00
gl_trunk: ; trunk: %11 pairs, red via color RAM
!byte $3c, $3c, $3c, $3c, $3c, $3c, $3c, $3c
; ---- the road: grey surface between two painted edge lines,
; from the horizon apex down to the screen corners, then the
; trees along both shoulders ----
@@ -88,25 +150,25 @@ road_row:
sbc road_off,x
tay
sty drleft
lda #$4e ; '/' diagonal
lda #CH_EDGEL ; grass, white line and road in one cell
sta (scrlo),y
lda #COL_EDGE
lda #MCOL_EDGE
sta (collo),y
lda #20
clc
adc road_off,x
tay
lda #$4d ; '\' diagonal
lda #CH_EDGER
sta (scrlo),y
lda #COL_EDGE
lda #MCOL_EDGE
sta (collo),y
dey ; fill the surface between the edges
rr_fill:
cpy drleft
beq rr_done
lda #$a0 ; inverse space: solid block
lda #CH_ROADF ; solid road surface
sta (scrlo),y
lda #COL_ROAD
lda #MCOL_ROAD
sta (collo),y
dey
jmp rr_fill
@@ -153,9 +215,9 @@ draw_tree:
jsr row_ptr
ldy tcol
iny
lda #$5d ; trunk
lda #CH_TRUNK
sta (scrlo),y
lda #BROWN
lda #MCOL_TRUNK
sta (collo),y
rts
@@ -187,9 +249,9 @@ erase_tree:
rts
tree_ball:
lda #$51 ; foliage ball
lda #CH_LEAF
sta (scrlo),y
lda #LGREEN
lda #MCOL_LEAF
sta (collo),y
rts
defs.asm
+21 -3
View File
@@ -5,9 +5,12 @@
; ---- hardware registers ----
RASTER = $d012 ; current raster line
XCTRL = $d016 ; horizontal fine scroll + 38/40 column mode
XCTRL = $d016 ; fine scroll + 38/40 cols + text multicolor
VMEM = $d018 ; VIC memory pointers: screen + charset
BORDER = $d020 ; border color register
BG = $d021 ; background color register
CHAR_MC1 = $d022 ; text multicolor 1 (bit pair %01)
CHAR_MC2 = $d023 ; text multicolor 2 (bit pair %10)
SCREEN = $0400 ; screen RAM (40x25 chars)
COLRAM = $d800 ; color RAM
SPRPTR = $07f8 ; sprite pointers (screen RAM + $3f8)
@@ -80,8 +83,23 @@ LGREY = 15
; ---- scene palette ----
COL_SKY = LBLUE ; background above the horizon
COL_GRASS = GREEN ; background below it
COL_ROAD = MGREY ; road surface (inverse-space fill)
COL_EDGE = WHITE ; painted road edge lines
COL_ROAD = MGREY ; road surface (via CHAR_MC2)
COL_LEAF = LGREEN ; tree foliage (via CHAR_MC1)
; ---- RAM charset: ROM copy + custom multicolor glyphs ----
; the road and the trees render as multicolor text cells
; (color RAM bit 3 set): pair %01 = CHAR_MC1 (foliage green),
; %10 = CHAR_MC2 (road grey), %11 = color RAM bits 0-2
CHSET = $3800 ; RAM charset location (VIC bank 0)
CH_EDGEL = $4e ; left road edge: grass|white line|road
CH_EDGER = $4d ; right road edge, mirrored
CH_ROADF = $6d ; solid road surface fill
CH_LEAF = $6e ; tree foliage ball
CH_TRUNK = $6f ; tree trunk
MCOL_EDGE = 8 + WHITE ; bit 3 turns the cell multicolor
MCOL_ROAD = 8
MCOL_LEAF = 8
MCOL_TRUNK = 8 + RED
; ---- joystick port 2 bits (after read_joy, active high) ----
JOY_LEFT = 4
main.asm
+4
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@@ -68,6 +68,7 @@ sprcol:
sta SPR_YEX
sta framectr
sta fheld
jsr charset_init ; RAM charset with the road/tree glyphs
jsr sfx_init
!ifdef AUTOPLAY { ; test builds boot straight into the game
@@ -133,3 +134,6 @@ wf_hit:
!src "sound.asm"
!src "music.asm"
!src "tables.asm"
!if * > CHSET {
!error "program ran into the RAM charset at $3800"
}
over.asm
+2
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@@ -7,6 +7,8 @@ over_init:
lda #BLACK ; clean card, the playfield is gone
sta bg_top
sta bg_bot
lda #$c8 ; plain text mode again
sta XCTRL
lda #0
sta SPR_EN
jsr clear_screen
play.asm
+2
View File
@@ -10,6 +10,8 @@ play_init:
sta bg_top
lda #COL_GRASS
sta bg_bot
lda #$d8 ; text multicolor on: road + tree cells
sta XCTRL
jsr clear_screen
jsr draw_road
tables.asm
+4 -4
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@@ -47,8 +47,8 @@ sprxreg:
sprbit:
!byte 2, 4, 8, 16, 32, 64, 128
; road edge offset per row (0-18): perspective curve
; wider at the horizon (offset 2) so it looks like a real road,
; not a sharp pyramid; only delta 0/1 steps, no visible jumps
; road edge offset per row (0-18): exactly one column per row,
; so the 45-degree edge glyphs join into one unbroken line on
; both sides, from the apex down to the screen corners
road_off:
!byte 2, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 17, 18
!byte 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18