M	EQU	Byte Ptr 0[BX]
	TITLE	'Draw Output Primitive Subroutines'
DGROUP	GROUP	DATA
; ****************************************************************************
; *                                                                          *
; *      DODRAWC : Generate Output Primitives                                *
; *                                                                          *
; ****************************************************************************
;                                                                            *
;  Revision : Nov. 02, 1983      File "DODRAWC.A86"   Version 1.0            *
;                                                                            ;
;***** MODE NOTES :  *********************************************************
;                                                                            *
;      1) LINE STYLE SUPPORT VARIABLES IN PUBLIC :                           *
;         LINE ENDPOINTS -  X0, Y0, XN, YN, SPECIL                           *
;         FILTER Y AND SET BIT FLAGS - ABOVE, INSIDE, ZONED                  *
;      2) Disk File Roll-Out on OBJLST Buffer OverFlow Supported by GETBYT   *
;         GETNXT routines                                                    *
;      3) Color Support
;  May-04-83    Set Writing Mode support                                     *
;***** MODE NOTES :  *********************************************************
;                                                                            ;
;  Calls    :                                                                *
;                                                                            *
;  GETXY  - Get the x,y coordinates of the next point in OBJLST (4 Bytes)    *
;  DRAWIT - Raster convert vector to pixel values, maps pixel                *
;                      to bitmap address and 'sets' the bit                  *
;                                                                            *
;  GETPT  : Get pt. coord. from PTSIN array (2 bytes)                        *
;  PUTPT  : Put pt. coord. into OBJLST buffer (2 bytes)                      *
;  PUTBYT : Put 1 byte into OBJLST buffer                                    *
;  GETBYT : Get 1 byte from OBJLST buffer                                    *
;  GETNXT : Get Next byte from OBJLST buffer                                 *
;  GETMIN : Returns in <hl> the smaller of <hl>, <de> values                 *
;  GETMAX : Retruns in <de> the larger of Values in <hl> and <de>            *
;                                                                            *
;*****************************************************************************
	PUBLIC	DOLINE, GETPT, PTADDR
	EXTRN	GETNXT:near, GETBYT:near, GETXY:near
	EXTRN	DRAWIT:near, ZSETCOR:near
	dseg
	EXTRN	BNEXT:word, RSTAT:byte
	extrn	bmaskl:byte, rflgl:byte, ritflg:byte, bitmask:byte
	EXTRN	NDLNCO:byte
	PUBLIC	NBIT, NBYT
	PUBLIC	X, X1, Y, Y1, X2, Y2, DX1, DY, XDIR, YDIR
	PUBLIC	FLG1, FLG2
	PUBLIC	X0, Y0, XN, YN, ABOVE, INSIDE, SPECIL
;----------------------------------------------------------------------------+
;        LINE DRAWING (RASTERIZE VECTOR TO PIXEL) VARIABLES                  +
;----------------------------------------------------------------------------+
X:
X1	RS	02	;line end points coordinates
Y:
Y1	RS	02
X0	RS	02	;Line start point coord.
Y0	RS	02
XN	RS	02	;Line end point coord.
YN	RS	02
X2	RS	02
Y2	RS	02
DX1	RS	02	;DX1 = x2 - x1
DY	RS	02	;dy = y2 - y1
XDIR	RS	01	;if DX1>0 then xdir = 1
			;if DX1=0 then xdir = 0
			;if DX1<0 then xdir = -1
YDIR	RS	01	;y direction indicator
FLG1	RS	01	;Position indicator of a point
FLG2	RS	01	;relative to the Current Plot Strip
			;        Line Style Support Variables
ABOVE	DB	0	;Which Line EndPoint ABOVE Strip Flag
INSIDE	DB	1	;Line EndPoints INSIDE Strip Flag
SPECIL	RS	02	;Line style bit pattern
;----------------------------------------------------------------------------+
NPT	RS	1	;No. of points
PTADDR	RS	2	;ADDRESS OF NEXT POINT IN PTSIN ARRAY
XPMIN	RS	2	;Polygon Min/Max Extents
YPMIN	RS	2
XPMAX	RS	2
YPMAX	RS	2
;----------------------------------------------------------------------------+
;        BITMAP BUFFER ADDRESSING VARIABLES                                  +
;----------------------------------------------------------------------------+
NBIT	RS	01	;bit location of a pixel = x mod 8 (0...7)
NBYT	RS	02	;byte location of a pixel in bitmap
        cseg
	EJECT
;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;        Polyline                                                            +
;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
DOLINE:
;	rflgl and bmaskl is set by the set color and set writing mode routines
	mov	al,rflgl	; setbit routine uses ritflg to decide
	mov	ritflg,al	; whether to OR, AND or to XOR the bit in
	mov	al,bmaskl	; the bitmap with the bitmask to produce
	mov	bitmask,al	; the new data bit 
	Mov	Bl, Byte Ptr NDLNCO
	Call	ZSETCOR		; Set up color for line

	CALL	GETNXT			;<a> = npt
;        Call polyline routine
	CALL	DRAWIT
	RET
;*****************************************************************************
;                                                                            *
;        GETPT : Get the next coordinate from PTSIN array                    *
;                                                                            *
;*****************************************************************************
;                                                                            *
;  Getpt(from, coord)                                                        *
;                                                                            *
;  CALL GETPT                                                                *
;        <DI> = Address of next coordinate in PTSIN                          *
;  RET                                                                       *
;        <DI> = Address of next Coordinate in PTSIN                          *
;        <DX> = The Coordinate                                               *
;                                                                            *
;*****************************************************************************
GETPT:
	MOV	DX,ES:DI
	ADD	DI,2
	RET
	END