dos33fsprogs/demos/second/part18_3d/draw_boxes.s
2023-10-11 01:02:15 -04:00

642 lines
10 KiB
ArmAsm

;==========================
; draw box scene
;==========================
; data in INL/INH
SET_COLOR = $C0 ; special case, color 0..15 in bottom nybble
END = $80 ; 0 :
CLEAR = $81 ; 0 : clear screen to black (0)
BOX = $82 ; 4 : x1,y1 to x2,y2
HLIN = $83 ; 3 : x1,x2 at y1
VLIN = $84 ; 3 : at x1 from y1 to y2
PLOT = $85 ; 2 : x1,y1
HLIN_ADD= $86 ; 2 : x1,x2 at prev_y1+1
HLIN_ADD_LSAME= $87 ; 1 : prev_x1,x2 at prev_y1+1
HLIN_ADD_RSAME= $88 ; 1 : x1,prev_x2 at prev_y1+1
BOX_ADD= $89 ; 3 : x1,prev_y1+1, x2, y2
BOX_ADD_LSAME= $8A ; 2 : prev_x1,prev_y1+1, x2, y2
BOX_ADD_RSAME= $8B ; 2 : x1,prev_y1+1, prev_x2, y2
VLIN_ADD= $8C ; 2 : at prev_x1+1 from y1 to y2
BLACK = $00
RED = $01
DARK_BLUE = $02
MAGENTA = $03
GREEN = $04
GREY1 = $05
MEDIUM_BLUE = $06
LIGHT_BLUE = $07
BROWN = $08
ORANGE = $09
GREY2 = $0A
PINK = $0B
LIGHT_GREEN = $0C
YELLOW = $0D
AQUA = $0E
WHITE = $0f
; top bit not set, command
; top bit set, repeat last command
; ??xx xxxx
; 00 = co-ord
; 10 = new command
; 11 = new-color
draw_scene:
lda #0 ; always clear to black
sta COLOR
jsr clear_fullgr
draw_scene_loop:
ldy #0
lda (INL),Y ; load next byte
bpl repeat_last ; if top bit 0, repeat last
; command
asl ; clear top bit
bmi set_color ; if negative, color
lsr ; shift back down
sta LAST_TYPE ; store last type
jsr inc_inl ; 16 bit increment
repeat_last:
lda LAST_TYPE
beq done_scene ; if 0, END
; use jump table for rest
and #$3f
tax
dex ; types start at 1
lda draw_table_h,X
sta table_jsr_smc+2
; pha
lda draw_table_l,X
; pha
sta table_jsr_smc+1
table_jsr_smc:
jsr $FFFF
;========================================
; adds A to input pointer and continues
update_pointer:
ldx LAST_TYPE
lda bytes_used,X
update_pointer_already_in_a:
clc
adc INL
sta INL
lda #0
adc INH
sta INH
bcc draw_scene_loop ; bra (would only be set if wrap $FFFF)
;============================
; done scene
;============================
; return
done_scene:
rts
;============================
; set color
;============================
; color is A*2h
set_color:
; make top and bottom byte the same
lsr ; shift back down
and #$f
sta COLOR
asl
asl
asl
asl
adc COLOR
sta COLOR
; special case as we are encoded differently from
; the actions
lda #1 ; we were one byte long
bne update_pointer_already_in_a ; bra
bytes_used:
.byte 0,0,4,3 ; END, CLEAR, BOX, HLIN
.byte 3,2,2,1 ; VLIN, PLOT, HLIN_ADD, HLIN_ADD_LSAME
.byte 1,3,2,2 ; HLIN_ADD_RSAME, BOX_ADD, BOX_ADD_LSAME
.byte 2,2 ; BOX_ADD_RSAME, VLIN_ADD
draw_table_l:
.byte <(clear_screen),<(draw_box),<(draw_hlin),<(draw_vlin)
.byte <(draw_plot)
.byte <(draw_hlin_add),<(draw_hlin_add_lsame),<(draw_hlin_add_rsame)
.byte <(draw_box_add),<(draw_box_add_lsame),<(draw_box_add_rsame)
.byte <(draw_vlin_add)
draw_table_h:
.byte >(clear_screen),>(draw_box),>(draw_hlin),>(draw_vlin)
.byte >(draw_plot)
.byte >(draw_hlin_add),>(draw_hlin_add_lsame),>(draw_hlin_add_rsame)
.byte >(draw_box_add),>(draw_box_add_lsame),>(draw_box_add_rsame)
.byte >(draw_vlin_add)
;=================================
;=================================
; clear screen
;=================================
;=================================
clear_screen:
jmp clear_fullgr ; tail call
;=================================
;=================================
; draw box
;=================================
;=================================
; blurgh. Cases
; Y1=EVEN, Y2=ODD -> loop Y1/2 to Y2/2, inclusive
; Y1=ODD, Y2=ODD -> HLIN, loop (Y1/2)+1 to Y2/2 inclusive
; Y1=EVEN, Y2=EVEN-> loop Y1/2 to (Y2/2)-1, HLIN
; Y1=ODD, Y2=EVEN -> HLIN, loop (Y1/2)+1 to (Y2/2)-1, HLIN
; 2/3 case, 1 to 1
; 3/5 case, (>1) 2 to 2
; 2/4 case, 1 to 1 (<2)
; 3/4 case, 2 to 1 (!)
; 3/6 case, 2 to 2
draw_box:
lda (INL),Y
sta X1
iny
lda (INL),Y
sta Y1
iny
draw_box_common_x2:
lda (INL),Y
sta X2
;==================================
; draw box common
;==================================
draw_box_common:
iny
lda (INL),Y
sta Y2 ; keep even though not necessary
lsr
; if even, go to one less
; else, fine
bcs odd_bottom_draw_box
even_bottom_draw_box:
sec
sbc #1
odd_bottom_draw_box:
sta draw_box_yend_smc+1
; see if we start at multiple of two
lda Y1
lsr
tay
bcc even_draw_box_start
; we're odd, need to call HLIN
jsr hlin_mask_odd
iny
even_draw_box_start:
draw_box_yloop:
draw_box_yend_smc:
cpy #0
bcc bbbb
beq bbbb
jmp done_draw_box_yloop ; bge
bbbb:
lda gr_offsets_l,Y
sta draw_box_xloop_smc+1
lda gr_offsets_h,Y
clc
adc DRAW_PAGE
sta draw_box_xloop_smc+2
lda COLOR
ldx X2
draw_box_xloop:
draw_box_xloop_smc:
sta $400,X
dex
cpx X1
bcs draw_box_xloop ; bge
iny
jmp draw_box_yloop
done_draw_box_yloop:
; done
; if Y2 was even we need to fixup and draw one more line
lda Y2
lsr
bcs definitely_odd_bottom
jsr hlin_mask_even
definitely_odd_bottom:
; done
rts
;=================================
;=================================
; draw hlin
;=================================
;=================================
draw_hlin:
lda (INL),Y
sta X1
iny
lda (INL),Y
sta X2
iny
lda (INL),Y
sta Y1 ; needed for HLIN_ADD
;===================================
;===================================
; hlin common code
;===================================
;===================================
; X1, X2 set up
; Y-coord is in A
; Y is A/2
hlin_common:
lsr
tay
bcc hlin_mask_even
hlin_mask_odd:
lda #$0F
.byte $2C ; bit trick
hlin_mask_even:
lda #$F0
sta MASK
eor #$FF
and COLOR
sta COLOR2
lda gr_offsets_l,Y
sta draw_hlin_l_xloop_smc+1
sta draw_hlin_s_xloop_smc+1
lda gr_offsets_h,Y
clc
adc DRAW_PAGE
sta draw_hlin_l_xloop_smc+2
sta draw_hlin_s_xloop_smc+2
ldx X2
draw_hlin_xloop:
draw_hlin_l_xloop_smc:
lda $400,X
and MASK
ora COLOR2
draw_hlin_s_xloop_smc:
sta $400,X
dex
cpx X1
bpl draw_hlin_xloop ; bge
rts
;=================================
;=================================
; draw hlin add
;=================================
;=================================
; increment Y1
draw_hlin_add:
lda (INL),Y
sta X1
iny
draw_hlin_add_lsame:
lda (INL),Y
sta X2
hlin_inc_y1:
inc Y1
lda Y1
jmp hlin_common
;=================================
;=================================
; draw hlin add_lsame
;=================================
;=================================
; increment Y1
; use old left value
;draw_hlin_add_lsame:
; lda (INL),Y
; sta X2
; jmp hlin_inc_y1
;=================================
;=================================
; draw hlin add_rsame
;=================================
;=================================
; increment Y1
; use old right value
draw_hlin_add_rsame:
lda (INL),Y
sta X1
jmp hlin_inc_y1
;=================================
;=================================
; draw box add
;=================================
;=================================
; increment Y2, put into Y1
draw_box_add:
lda Y2
sta Y1
inc Y1
lda (INL),Y
sta X1
iny
jmp draw_box_common_x2
;=================================
;=================================
; draw box add_lsame
;=================================
;=================================
; increment Y2, store in Y1
; use old X1 value
draw_box_add_lsame:
lda Y2
sta Y1
inc Y1
jmp draw_box_common_x2
;=================================
;=================================
; draw box add_rsame
;=================================
;=================================
; increment Y2, put in Y1
; use old right value X2
draw_box_add_rsame:
lda Y2
sta Y1
inc Y1
lda (INL),Y
sta X1
jmp draw_box_common
;=================================
;=================================
; draw vlin add
;=================================
;=================================
draw_vlin_add:
inc X1 ; X1 is prev_X1+1
bne draw_vlin_skip_x1 ; bra
;=================================
;=================================
; draw vlin
;=================================
;=================================
draw_vlin:
lda (INL),Y
sta X1
iny
draw_vlin_skip_x1:
lda (INL),Y
sta Y1
iny
lda (INL),Y
sta Y2
;================================
draw_vlin_common:
lda Y2
lsr
; if even, go to one less
; else, fine
bcs odd_bottom_vlin
even_bottom_vlin:
sec
sbc #1
odd_bottom_vlin:
sta vlin_yend_smc+1
; handle top
; see if we start at multiple of two
lda Y1
lsr
tay ; needed! Sets Y for vlin_yloop
bcc even_vlin_start
odd_vlin_start:
; we're odd, need to call PLOT
lda Y1
jsr plot_common
iny ; update Y for vlin_yloop
even_vlin_start:
vlin_yloop:
vlin_yend_smc:
cpy #0
bcc cccc
beq cccc
jmp done_vlin_yloop ;
cccc:
lda gr_offsets_l,Y
sta vlin_xloop_smc+1
lda gr_offsets_h,Y
clc
adc DRAW_PAGE
sta vlin_xloop_smc+2
lda COLOR
ldx X1
vlin_xloop_smc:
sta $400,X
iny
jmp vlin_yloop
; done
done_vlin_yloop:
; if Y2 was even we need to fixup and draw one more line
lda Y2
lsr
bcs definitely_odd_vlin
lda Y2
jmp plot_common ; plot_mask_even (tail call)
definitely_odd_vlin:
; done
rts
;=================================
;=================================
; draw plot
;=================================
;=================================
draw_plot:
lda (INL),Y
sta X1
iny
lda (INL),Y
sta Y1 ; needed for HLIN_ADD
; fallthrough
;===================================
;===================================
; plot common code
;===================================
;===================================
; X-coord in X1
; Y-coord in A
; Y is Y-coord/2 at end
plot_common:
lsr ; need Y-coord/2 because 2 rows per byte
tay
bcc plot_mask_even
plot_mask_odd:
lda #$0F
.byte $2C ; bit trick
plot_mask_even:
lda #$F0
sta MASK
eor #$FF
and COLOR
sta COLOR2
lda gr_offsets_l,Y
sta plot_l_smc+1
sta plot_s_smc+1
lda gr_offsets_h,Y
clc
adc DRAW_PAGE
sta plot_l_smc+2
sta plot_s_smc+2
ldx X1
plot_l_smc:
lda $400,X
and MASK
ora COLOR2
plot_s_smc:
sta $400,X
rts
;===========================
; 16-bit increment of INL
; inline this?
inc_inl:
inc INL
bne done_inc_inl
inc INH
done_inc_inl:
rts
.include "gr_fast_clear.s"
gr_offsets_l:
.byte <$400,<$480,<$500,<$580,<$600,<$680,<$700,<$780
.byte <$428,<$4a8,<$528,<$5a8,<$628,<$6a8,<$728,<$7a8
.byte <$450,<$4d0,<$550,<$5d0,<$650,<$6d0,<$750,<$7d0
gr_offsets_h:
.byte >$400,>$480,>$500,>$580,>$600,>$680,>$700,>$780
.byte >$428,>$4a8,>$528,>$5a8,>$628,>$6a8,>$728,>$7a8
.byte >$450,>$4d0,>$550,>$5d0,>$650,>$6d0,>$750,>$7d0