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mode7: rasterbars, all colors

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This commit is contained in:
Vince Weaver 2018-01-22 23:41:43 -05:00
parent d8de617a06
commit a8422779fa
1 changed files with 66 additions and 19 deletions
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85
mode7/rasterbars.s
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@ -50,13 +50,43 @@ init_rows:
lda #COLOR_BOTH_AQUA ; aqua
sta COLOR
ldy SCREEN_Y
jsr set_row_color
; lda #6 ; medium blue
; iny
; jsr set_row_color
lda #COLOR_BOTH_MEDIUMBLUE ; medium blue
sta COLOR
iny
jsr set_row_color
lda #COLOR_BOTH_LIGHTGREEN ; light green
sta COLOR
iny
jsr set_row_color
lda #COLOR_BOTH_DARKGREEN ; green
sta COLOR
iny
jsr set_row_color
lda #COLOR_BOTH_YELLOW ; yellow
sta COLOR
iny
jsr set_row_color
lda #COLOR_BOTH_ORANGE ; orange
sta COLOR
iny
jsr set_row_color
lda #COLOR_BOTH_PINK ; pink
sta COLOR
iny
jsr set_row_color
lda #COLOR_BOTH_RED ; red
sta COLOR
iny
jsr set_row_color
;=================
; draw rows
@ -119,16 +149,16 @@ not_there:
; Y preserved?
set_row_color:
tya
tya ; wrap y offset
and #(ELEMENTS-1)
tax
lda fine_sine,X
cpx #33
bpl sin_negative
lda fine_sine,X ; lookup sign value
cpx #33 ; check if > pi and
bpl sin_negative ; need to make negative
sin_positive:
clc
clc ; shift right by 4, zero-extend
ror
clc
ror
@ -137,12 +167,8 @@ sin_positive:
clc
ror
clc
adc #18
lsr
tax
lda COLOR
sta row_color,X
adc #18 ; add in 18 to center on screen
lsr ; shift once more
jmp sin_no_more
@ -162,12 +188,33 @@ sin_negative:
adc #18
lsr
tax
lda COLOR
sta row_color,X
sin_no_more:
tax
and #$1 ; see if even or odd
beq even_line
lda COLOR
and #$f0
sta COLOR
lda row_color,X
and #$0f
jmp done_line
even_line:
lda COLOR
and #$0f
sta COLOR
lda row_color,X
and #$f0
done_line:
ora COLOR
sta row_color,X
rts
;===============================================