oval: add bot version

graphics/gr/plasma/oval_bot.s

@@ -0,0 +1,174 @@
+; Ovals
+
+; zero page
+GBASL	= $26
+GBASH	= $27
+MASK	= $2E
+COLOR	= $30
+;CTEMP	= $68
+YY	= $69
+
+FRAME	= $FC
+SUM	= $FD
+SAVEX	= $FE
+SAVEY	= $FF
+
+; soft-switches
+FULLGR	= $C052
+PAGE1	= $C054
+
+; ROM routines
+PLOT    = $F800                 ;; PLOT AT Y,A
+PLOT1	= $F80E		;; PLOT at (GBASL),Y (need MASK to be $0f or $f0)
+GBASCALC= $F847		;; take Y-coord/2 in A, put address in GBASL/H ( a trashed, C clear)
+SETCOL  = $F864		;; COLOR=A*17
+SETGR	= $FB40
+
+
+
+	;================================
+	; Clear screen and setup graphics
+	;================================
+oval:
+
+	jsr	SETGR		; set lo-res 40x40 mode
+	bit	FULLGR		; make it 40x48
+
+draw_oval:
+	inc	FRAME
+
+	ldx	#47		; YY
+create_yloop:
+
+	ldy	#39
+	txa
+	jsr	PLOT	; (Y,A) sets GBASL/GBASH, Y
+
+create_xloop:
+
+;	lda	#128
+	lda	FRAME
+	sta	SUM
+
+	tya			; XX
+	jsr	calcsine_div2
+
+	txa			; YY
+	jsr	calcsine
+
+	; X (YY) is in SAVEX
+
+	clc
+;	sty	SAVEY		; XX
+	tya
+	adc	SAVEX		; XX + YY
+	jsr	calcsine_div2
+
+;	clc
+;	adc	FRAME
+
+	lsr				; double colors
+	and	#$7			; mask
+	tax
+	lda	colorlookup,X
+
+	jsr	SETCOL
+
+	jsr	PLOT1		; PLOT (GBASL),Y
+
+	ldx	SAVEX
+
+	dey
+	bpl	create_xloop
+
+	dex
+	bpl	create_yloop
+
+	; X and Y both $FF
+
+	bmi	draw_oval
+
+
+
+calcsine_div2:
+	lsr
+calcsine:
+	stx	SAVEX
+
+	and	#$3f
+
+	tax
+	rol
+	rol
+	rol
+	bcc	sinadd
+
+sinsub:
+	lda	#0
+	lda	SUM
+;	sec
+	sbc	sinetable-32,X
+	jmp	sindone
+
+sinadd:
+	lda	SUM
+;	clc
+	adc	sinetable,X
+
+sindone:
+	sta	SUM
+
+	ldx	SAVEX
+	rts
+
+
+colorlookup:
+
+; blue
+;.byte $55,$77,$ff,$77,$66,$22,$55	; use 00 from sinetable
+;.byte $00
+
+; pink
+.byte $55,$11,$33,$bb,$ff,$bb,$55
+;.byte $00
+
+; green
+;.byte $55,$44,$cc,$ff,$cc,$44,$55	; use 00 from sinetable
+;.byte $00
+
+; orange
+;.byte $99,$88,$ff,$44,$cc,$ff,$55	; use 00 from sinetable
+;.byte $00
+
+;.byte $00,$00,$55,$55,$77,$77,$ff,$ff
+;.byte $77,$77,$66,$66,$22,$22,$55,$55
+
+
+sinetable:
+; this is actually (32*sin(x))
+
+.byte $00,$03,$06,$09,$0C,$0F,$11,$14
+.byte $16,$18,$1A,$1C,$1D,$1E,$1F,$1F
+.byte $20,$1F,$1F,$1E,$1D,$1C,$1A,$18
+.byte $16,$14,$11,$0F,$0C,$09,$06,$03
+;.byte $00,$FD,$FA,$F7,$F4,$F1,$EF,$EC
+;.byte $EA,$E8,$E6,$E4,$E3,$E2,$E1,$E1
+;.byte $E0,$E1,$E1,$E2,$E3,$E4,$E6,$E8
+;.byte $EA,$EC,$EF,$F1,$F4,$F7,$FA,$FD
+
+
+;.byte $00,$06,$0C,$11,$16,$1A,$1D,$1F
+;.byte $20,$1F,$1D,$1A,$16,$11,$0C,$06
+;.byte $00,$FA,$F4,$EF,$EA,$E6,$E3,$E1
+;.byte $E0,$E1,$E3,$E6,$EA,$EF,$F4,$FA
+
+;.byte $00,$0C,$16,$1D
+;.byte $20,$1D,$16,$0C
+;.byte $00,$F4,$EA,$E3
+;.byte $E0,$E3,$EA,$F4
+
+	jmp	oval
+
+
+	; 131 bytes
+	; 3f5 - 128 = 375