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hgr: lines: minor changes

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This commit is contained in:
Vince Weaver 2021-07-28 08:44:22 -04:00
parent 068ed6a85b
commit 47336d1189
1 changed files with 13 additions and 17 deletions
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30
graphics/hgr/lines/lines.s
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@ -5,6 +5,8 @@
; based on pseudo-code from
; https://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm
; 361 bytes -- first working code
; D0+ used by HGR routines
HGR_COLOR = $E4
@ -75,6 +77,12 @@ reset:
left_lines_loop:
lda FRAME
and #$7
tax
; ldx #7
jsr HCOLOR1 ; set color
jsr draw_line
lda Y1
@ -82,7 +90,7 @@ left_lines_loop:
adc #8
sta Y1
lda X2_L ; 280/24 = 140/12 = 70/6 = 11
lda X2_L ; 280/24 = 140/12 = 70/6 = 11
clc
adc #11
sta X2_L
@ -140,20 +148,14 @@ noc2:
bne right_lines_loop
;============================
;=========================================
; draw line
; from x1,y1 to x2,y2
;============================
;=========================================
; note: x1,y1 points to x2,y2 at the end?
; x2,y2 unchanged
draw_line:
; lda FRAME
; and #$7
; tax
ldx #7
jsr HCOLOR1 ; set color
lda X1_L
sta B_X1_L
lda X1_H
@ -168,8 +170,6 @@ draw_line:
lda Y2
sta B_Y2
; from wikipedia
; dx = abs(x2 - x1)
@ -384,10 +384,6 @@ doit:
lda B_Y1
adc B_SY
sta B_Y1
; lda B_Y1_H
; adc #0
; sta B_Y1_H
skip_y: