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graphics: lines: look into recursive

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This commit is contained in:
Vince Weaver 2021-03-28 18:04:19 -04:00
parent d0775b32f1
commit 89d706cb0e
2 changed files with 149 additions and 2 deletions
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13
graphics/gr/lines/Makefile
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@ -7,7 +7,7 @@ EMPTYDISK = ../../../empty_disk/empty.dsk
all: lines.dsk
lines.dsk: HELLO LINES LINES_SMALL LINES_ROM LINES_WIKI LINES_BOT
lines.dsk: HELLO LINES LINES_SMALL LINES_ROM LINES_WIKI LINES_BOT LINES_RECURSE
cp $(EMPTYDISK) lines.dsk
$(DOS33) -y lines.dsk SAVE A HELLO
$(DOS33) -y lines.dsk BSAVE -a 0xC00 LINES
@ -15,6 +15,7 @@ lines.dsk: HELLO LINES LINES_SMALL LINES_ROM LINES_WIKI LINES_BOT
$(DOS33) -y lines.dsk BSAVE -a 0xC00 LINES_ROM
$(DOS33) -y lines.dsk BSAVE -a 0xC00 LINES_WIKI
$(DOS33) -y lines.dsk BSAVE -a 0x36B LINES_BOT
$(DOS33) -y lines.dsk BSAVE -a 0xC00 LINES_RECURSE
###
@ -55,6 +56,14 @@ lines_wiki.o: lines_wiki.s
###
LINES_RECURSE: lines_recurse.o
ld65 -o LINES_RECURSE lines_recurse.o -C $(LINKERSCRIPTS)/apple2_c00.inc
lines_recurse.o: lines_recurse.s
ca65 -o lines_recurse.o lines_recurse.s -l lines_recurse.lst
###
LINES_BOT: lines_bot.o
ld65 -o LINES_BOT lines_bot.o -C ./apple2_36b.inc
@ -64,4 +73,4 @@ lines_bot.o: lines_bot.s
###
clean:
rm -f *~ *.o *.lst HELLO LINES LINES_SMALL LINES_ROM LINES_WIKI LINES_BOT
rm -f *~ *.o *.lst HELLO LINES LINES_SMALL LINES_ROM LINES_WIKI LINES_BOT LINES_RECURSE

138
graphics/gr/lines/lines_recurse.s Normal file
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@ -0,0 +1,138 @@
; Bresenham Lines
; by Vince `deater` Weaver <vince@deater.net>
; http://www.retroprogramming.com/2016/05/divide-and-conquer-line-algorithm-for.html
.include "zp.inc"
.include "hardware.inc"
B_X1 = $F0
B_Y1 = $F1
B_X2 = $F2
B_Y2 = $F3
COUNT = $F9
X1 = $1000
Y1 = $1100
X2 = $1200
Y2 = $1300
MIDX = $1400
MIDY = $1500
lines:
jsr SETGR ; set lo-res 40x40 mode
; A=$D0 afterward
restart:
lda #0
sta COUNT
lines_loop:
jsr NEXTCOL
lda #0
sta X1
lda #36
sta Y2
lda COUNT
cmp #10
;end:
beq restart
asl
asl
sta Y1
sta X2
jsr draw_line
inc COUNT
jmp lines_loop
;============================
; draw line
; from x1,y1 to x2,y2
;============================
draw_line:
ldx #0
draw_recurse:
;int draw ( ax, ay, bx, by )
;{
; int midx, midy;
; midx = ( ax+bx ) / 2;
; midy = ( ay+by ) / 2;
; if ( midx != ax && midy != ay )
; {
; draw( midx, midy, ax, ay );
; draw( bx, by, midx, midy );
; plot( midx, midy );
; }
;}
clc
lda X1,X
adc X2,X
lsr
sta MIDX,X
tay
clc
lda Y1,X
adc Y2,X
lsr
sta MIDY,X
; plot midx,midy
jsr PLOT ;; PLOT AT Y,A (A colors output, Y preserved)
; check if done
lda X1,X
cmp MIDX,X
bne recurse
lda Y1,X
cmp MIDY,X
beq done_draw_line
recurse:
; draw( ax, ay, midx, midy);
lda MIDX,X
sta X1+1,X
lda MIDY,X
sta Y1+1,X
lda X1,X
sta X2+1,X
lda Y1,X
sta Y2+1,X
inx
jsr draw_recurse
; draw( bx, by, midx, midy );
lda X2,X
sta X1+1,X
lda Y2,X
sta Y1+1,X
lda MIDX,X
sta X2+1,X
lda MIDY,X
sta Y2+1,X
inx
jsr draw_recurse
done_draw_line:
dex
rts