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gfx2.text() per-pixel positioning implemented for screen modes 1 and 5
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@irmen
irmen committed Jul 24, 2023
1 parent 2f756f1 commit 3b90be2
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138 changes: 101 additions & 37 deletions compiler/res/prog8lib/cx16/gfx2.p8
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
; mode 6 = bitmap 640 x 480 x 4c
; higher color dephts in highres are not supported due to lack of VRAM

; TODO remove the phx/plx pairs in non-stack compiler version

gfx2 {

Expand Down Expand Up @@ -986,48 +987,96 @@ skip:
sub text(uword @zp x, uword y, ubyte color, uword sctextptr) {
; -- Write some text at the given pixel position. The text string must be in screencode encoding (not petscii!).
; You must also have called text_charset() first to select and prepare the character set to use.
; NOTE: in monochrome (1bpp) screen modes, x position is currently constrained to multiples of 8 ! TODO allow per-pixel horizontal positioning
; TODO draw whole horizontal spans using vera auto increment if possible, instead of per-character columns
uword chardataptr
ubyte[8] @shared char_bitmap_bytes_left
ubyte[8] @shared char_bitmap_bytes_right

when active_mode {
1, 5 -> {
; monochrome mode, either resolution
cx16.r2 = 40
if active_mode==5
cx16.r2 = 80
while @(sctextptr) {
chardataptr = charset_addr + (@(sctextptr) as uword)*8
cx16.vaddr(charset_bank, chardataptr, 1, 1)
position(x,y)
cx16.r3 = sctextptr
while @(cx16.r3) {
chardataptr = charset_addr + @(cx16.r3) * $0008
; copy the character bitmap into RAM
cx16.vaddr_autoincr(charset_bank, chardataptr, 0, 1)
%asm {{
lda cx16.VERA_ADDR_H
and #%111 ; don't auto-increment, we have to do that manually because of the ora
sta cx16.VERA_ADDR_H
lda color
; pre-shift the bits
phx ; TODO remove in non-stack version
lda text.x
and #7
sta P8ZP_SCRATCH_B1
ldy #8
- lda P8ZP_SCRATCH_B1
bne + ; white color, plot normally
lda cx16.VERA_DATA1
eor #255 ; black color, keep only the other pixels
and cx16.VERA_DATA0
bra ++
+ lda cx16.VERA_DATA0
ora cx16.VERA_DATA1
+ sta cx16.VERA_DATA0
lda cx16.VERA_ADDR_L
clc
adc cx16.r2
sta cx16.VERA_ADDR_L
bcc +
inc cx16.VERA_ADDR_M
+ inc x
bne +
inc x+1
+ dey
ldy #0
- lda cx16.VERA_DATA0
stz P8ZP_SCRATCH_REG
ldx P8ZP_SCRATCH_B1
cpx #0
beq +
- lsr a
ror P8ZP_SCRATCH_REG
dex
bne -
+ sta char_bitmap_bytes_left,y
lda P8ZP_SCRATCH_REG
sta char_bitmap_bytes_right,y
iny
cpy #8
bne --
plx ; TODO remove in non-stack version
}}
sctextptr++
; left part of shifted char
position2(x, y, true)
set_autoincrs_mode1_or_5()
if color {
%asm {{
ldy #0
- lda char_bitmap_bytes_left,y
ora cx16.VERA_DATA1
sta cx16.VERA_DATA0
iny
cpy #8
bne -
}}
} else {
%asm {{
ldy #0
- lda char_bitmap_bytes_left,y
eor #255
and cx16.VERA_DATA1
sta cx16.VERA_DATA0
iny
cpy #8
bne -
}}
}
; right part of shifted char
if lsb(x) & 7 {
position2(x+8, y, true)
set_autoincrs_mode1_or_5()
if color {
%asm {{
ldy #0
- lda char_bitmap_bytes_right,y
ora cx16.VERA_DATA1
sta cx16.VERA_DATA0
iny
cpy #8
bne -
}}
} else {
%asm {{
ldy #0
- lda char_bitmap_bytes_right,y
eor #255
and cx16.VERA_DATA1
sta cx16.VERA_DATA0
iny
cpy #8
bne -
}}
}
}
cx16.r3++
x += 8
}
}
4 -> {
Expand All @@ -1039,7 +1088,7 @@ skip:
position(x,y)
y++
%asm {{
phx
phx ; TODO remove in non-stack version
ldx color
lda cx16.VERA_DATA1
sta P8ZP_SCRATCH_B1
Expand All @@ -1051,7 +1100,7 @@ skip:
+ lda cx16.VERA_DATA0 ; don't write a pixel, but do advance to the next address
+ dey
bne -
plx
plx ; TODO remove in non-stack version
}}
}
x+=8
Expand All @@ -1068,7 +1117,7 @@ skip:
chardataptr = charset_addr + (@(sctextptr) as uword)*8
cx16.vaddr(charset_bank, chardataptr, 1, true) ; for reading the chardata from Vera data channel 1
repeat 8 {
; TODO rewrite this inner loop partly in assembly:
; TODO rewrite this in assembly, don't call plot for every pixel
; requires expanding the charbits to 2-bits per pixel (based on color)
; also it's way more efficient to draw whole horizontal spans instead of per-character
cx16.r9L = cx16.VERA_DATA1 ; get the next 8 horizontal character bits
Expand All @@ -1087,6 +1136,21 @@ skip:
}
}
}

sub set_autoincrs_mode1_or_5() {
; set autoincrements to go to next pixel row (40 or 80 increment)
if active_mode==1 {
cx16.VERA_CTRL = 0
cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & $0f | (11<<4)
cx16.VERA_CTRL = 1
cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & $0f | (11<<4)
} else {
cx16.VERA_CTRL = 0
cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & $0f | (12<<4)
cx16.VERA_CTRL = 1
cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & $0f | (12<<4)
}
}
}

asmsub cs_innerloop640() clobbers(Y) {
Expand Down
30 changes: 15 additions & 15 deletions examples/test.p8
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Original file line number Diff line number Diff line change
@@ -1,20 +1,20 @@
%import gfx2

main
{
sub start()
{
cx16.set_screen_mode(128)

cx16.vaddr_autoincr(0,320*100+100,1,2)
repeat 16 {
cx16.VERA_DATA1 = 0
}
cx16.vaddr_autodecr(0,320*110+100,1,1)
repeat 16 {
cx16.VERA_DATA1 = 0
}
main {
sub start() {
gfx2.screen_mode(1) ; 1 and 5 are lo-res and hi-res monochrome

repeat {
uword xx
gfx2.rect(10, 10, 180, 140, 3)
gfx2.rect(12, 12, 180, 140, 3)
for xx in 5 to 100 {
gfx2.text(xx, xx, 1, sc:"hello world! should be pixel-aligned.")
sys.waitvsync()
sys.waitvsync()
gfx2.text(xx, xx, 0, sc:"hello world! should be pixel-aligned.")
}
}

repeat { }
}
}

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