src/px/pcond2.c

#ifndef lint
static const char       RCSid[] = "$Id: pcond2.c,v 3.18 2015/08/21 05:48:28 greg Exp $";
#endif
/*
 * Input and output conditioning routines for pcond.
 *  Added white-balance adjustment 10/01 (GW).
 */

#include "pcond.h"
#include "warp3d.h"


RGBPRIMP        inprims = stdprims;     /* input primaries */
COLORMAT        inrgb2xyz;              /* convert input RGB to XYZ */
RGBPRIMP        outprims = stdprims;    /* output primaries */

double  (*lumf)() = rgblum;             /* input luminance function */
double  inpexp = 1.0;                   /* input exposure value */

char    *mbcalfile = NULL;              /* macbethcal mapping file */
char    *cwarpfile = NULL;              /* color space warping file */

static struct mbc {
        COLORMAT        cmat;
        float   xa[3][6], ya[3][6];
        COLOR   cmin, cmax;
}       mbcond;                         /* macbethcal conditioning struct */

static WARP3D   *cwarp;                 /* color warping structure */

static COLOR    *scanbuf;               /* scanline processing buffer */
static int      nread;                  /* number of scanlines processed */

static void sfscan(COLOR *sl, int len, double sf);
static void matscan(COLOR *sl, int len, COLORMAT mat);
static void mbscan(COLOR *sl, int len, struct mbc *mb);
static void cwscan(COLOR *sl, int len, WARP3D *wp);
static void getmbcalfile(char *fn, struct mbc *mb);


double
rgblum(         /* compute (scotopic) luminance of RGB color */
        COLOR   clr,
        int     scotopic
)
{
        if (scotopic)           /* approximate */
                return( WHTSEFFICACY * (colval(clr,RED)*.062 +
                        colval(clr,GRN)*.608 + colval(clr,BLU)*.330) );
        return( WHTEFFICACY * (colval(clr,RED)*inrgb2xyz[1][0] +
                        colval(clr,GRN)*inrgb2xyz[1][1] +
                        colval(clr,BLU)*inrgb2xyz[1][2]) );
}


double
cielum(         /* compute (scotopic) luminance of CIE color */
        COLOR   xyz,
        int     scotopic
)
{
        if (scotopic)           /* approximate */
                return(colval(xyz,CIEY) *
                        (1.33*(1. + (colval(xyz,CIEY)+colval(xyz,CIEZ))/
                        colval(xyz,CIEX)) - 1.68));
        return(colval(xyz,CIEY));
}


COLOR *
nextscan(void)                          /* read and condition next scanline */
{
        if (nread >= numscans(&inpres)) {
                if (cwarpfile != NULL)
                        free3dw(cwarp);
                free((void *)scanbuf);
                return(scanbuf = NULL);
        }
        if (what2do&DO_ACUITY)
                acuscan(scanbuf, nread);
        else if (fread2scan(scanbuf, scanlen(&inpres), infp,
                                NCSAMP, WLPART) < 0) {
                fprintf(stderr, "%s: %s: scanline read error\n",
                                progname, infn);
                exit(1);
        }
        if (what2do&DO_VEIL)                    /* add veiling */
                addveil(scanbuf, nread);
        if (what2do&DO_COLOR)                   /* scotopic color loss */
                scotscan(scanbuf, scanlen(&inpres));
        if (what2do&DO_LINEAR)                  /* map luminances */
                sfscan(scanbuf, scanlen(&inpres), scalef);
        else
                mapscan(scanbuf, scanlen(&inpres));
        if (mbcalfile != NULL)                  /* device color correction */
                mbscan(scanbuf, scanlen(&inpres), &mbcond);
        else if (cwarpfile != NULL)             /* device color space warp */
                cwscan(scanbuf, scanlen(&inpres), cwarp);
        else if ((lumf == cielum) | (inprims != outprims))
                matscan(scanbuf, scanlen(&inpres), mbcond.cmat);
        nread++;
        return(scanbuf);
}


COLOR *
firstscan(void)                         /* return first processed scanline */
{
        if (mbcalfile != NULL)          /* load macbethcal file */
                getmbcalfile(mbcalfile, &mbcond);
        else if (cwarpfile != NULL) {
                if ((cwarp = load3dw(cwarpfile, NULL)) == NULL)
                        syserror(cwarpfile);
        } else
                if (lumf == rgblum)
                        comprgb2rgbWBmat(mbcond.cmat, inprims, outprims);
                else
                        compxyz2rgbWBmat(mbcond.cmat, outprims);
        if (what2do&DO_ACUITY)
                initacuity();
        scanbuf = (COLOR *)malloc(scanlen(&inpres)*sizeof(COLOR));
        if (scanbuf == NULL)
                syserror("malloc");
        nread = 0;
        return(nextscan());
}


static void
sfscan(                 /* apply scalefactor to scanline */
        COLOR   *sl,
        int     len,
        double  sf
)
{
        while (len--) {
                scalecolor(sl[0], sf);
                sl++;
        }
}


static double
greypoint(                      /* compute gamut mapping grey target */
        COLOR col
)
{
        COLOR   gryc;
        int     i;
                                /* improves saturated color rendering */
        copycolor(gryc, col);
        for (i = 3; i--; )
                if (gryc[i] > 1)
                        gryc[i] = 1;
                else if (gryc[i] < 0)
                        gryc[i] = 0;
        return(bright(gryc));
}


static void
matscan(                        /* apply color matrix to scaline */
        COLOR   *sl,
        int     len,
        COLORMAT        mat
)
{
        while (len--) {
                colortrans(sl[0], mat, sl[0]);
                clipgamut(sl[0], greypoint(sl[0]), CGAMUT, cblack, cwhite);
                sl++;
        }
}


static void
mbscan(                 /* apply macbethcal adj. to scaline */
        COLOR   *sl,
        int     len,
        struct mbc      *mb
)
{
        double  d;
        int     i, j;

        while (len--) {
                colortrans(sl[0], mb->cmat, sl[0]);
                clipgamut(sl[0], greypoint(sl[0]), CGAMUT, mb->cmin, mb->cmax);
                for (i = 0; i < 3; i++) {
                        d = colval(sl[0],i);
                        for (j = 0; j < 4 && mb->xa[i][j+1] <= d; j++)
                                ;
                        colval(sl[0],i) = ( (mb->xa[i][j+1] - d)*mb->ya[i][j] +
                                        (d - mb->xa[i][j])*mb->ya[i][j+1] ) /
                                        (mb->xa[i][j+1] - mb->xa[i][j]);
                }
                sl++;
        }
}


static void
cwscan(                 /* apply color space warp to scaline */
        COLOR   *sl,
        int     len,
        WARP3D  *wp
)
{
        int     rval;

        while (len--) {
                rval = warp3d(sl[0], sl[0], wp);
                if (rval & W3ERROR)
                        syserror("warp3d");
                if (rval & W3BADMAP) {
                        fprintf(stderr, "%s: %s: bad color space map\n",
                                        progname, cwarpfile);
                        exit(1);
                }
                clipgamut(sl[0], greypoint(sl[0]), CGAMUT, cblack, cwhite);
                sl++;
        }
}


static void
getmbcalfile(                   /* load macbethcal file */
        char    *fn,
        struct mbc      *mb
)
{
        char    buf[128];
        FILE    *fp;
        int     inpflags = 0;
        int     i;

        if ((fp = fopen(fn, "r")) == NULL)
                syserror(fn);
        while (fgets(buf, sizeof(buf), fp) != NULL) {
                if (!(inpflags & 01) &&
                                sscanf(buf,
                                "rxa(i) : select(i,%f,%f,%f,%f,%f,%f)",
                                &mb->xa[0][0], &mb->xa[0][1],
                                &mb->xa[0][2], &mb->xa[0][3],
                                &mb->xa[0][4], &mb->xa[0][5]
                                ) == 6)
                        inpflags |= 01;
                else if (!(inpflags & 02) &&
                                sscanf(buf,
                                "rya(i) : select(i,%f,%f,%f,%f,%f,%f)",
                                &mb->ya[0][0], &mb->ya[0][1],
                                &mb->ya[0][2], &mb->ya[0][3],
                                &mb->ya[0][4], &mb->ya[0][5]
                                ) == 6)
                        inpflags |= 02;
                else if (!(inpflags & 04) &&
                                sscanf(buf,
                                "gxa(i) : select(i,%f,%f,%f,%f,%f,%f)",
                                &mb->xa[1][0], &mb->xa[1][1],
                                &mb->xa[1][2], &mb->xa[1][3],
                                &mb->xa[1][4], &mb->xa[1][5]
                                ) == 6)
                        inpflags |= 04;
                else if (!(inpflags & 010) &&
                                sscanf(buf,
                                "gya(i) : select(i,%f,%f,%f,%f,%f,%f)",
                                &mb->ya[1][0], &mb->ya[1][1],
                                &mb->ya[1][2], &mb->ya[1][3],
                                &mb->ya[1][4], &mb->ya[1][5]
                                ) == 6)
                        inpflags |= 010;
                else if (!(inpflags & 020) &&
                                sscanf(buf,
                                "bxa(i) : select(i,%f,%f,%f,%f,%f,%f)",
                                &mb->xa[2][0], &mb->xa[2][1],
                                &mb->xa[2][2], &mb->xa[2][3],
                                &mb->xa[2][4], &mb->xa[2][5]
                                ) == 6)
                        inpflags |= 020;
                else if (!(inpflags & 040) &&
                                sscanf(buf,
                                "bya(i) : select(i,%f,%f,%f,%f,%f,%f)",
                                &mb->ya[2][0], &mb->ya[2][1],
                                &mb->ya[2][2], &mb->ya[2][3],
                                &mb->ya[2][4], &mb->ya[2][5]
                                ) == 6)
                        inpflags |= 040;
                else if (!(inpflags & 0100) &&
                                sscanf(buf,
                                "ro = %f*rn + %f*gn + %f*bn",
                                &mb->cmat[0][0], &mb->cmat[0][1],
                                &mb->cmat[0][2]) == 3)
                        inpflags |= 0100;
                else if (!(inpflags & 0200) &&
                                sscanf(buf,
                                "go = %f*rn + %f*gn + %f*bn",
                                &mb->cmat[1][0], &mb->cmat[1][1],
                                &mb->cmat[1][2]) == 3)
                        inpflags |= 0200;
                else if (!(inpflags & 0400) &&
                                sscanf(buf,
                                "bo = %f*rn + %f*gn + %f*bn",
                                &mb->cmat[2][0], &mb->cmat[2][1],
                                &mb->cmat[2][2]) == 3)
                        inpflags |= 0400;
        }
        if (inpflags != 0777) {
                fprintf(stderr,
                "%s: cannot grok macbethcal file \"%s\" (inpflags==0%o)\n",
                        progname, fn, inpflags);
                exit(1);
        }
        fclose(fp);
                                        /* compute gamut */
        for (i = 0; i < 3; i++) {
                colval(mb->cmin,i) = mb->xa[i][0] -
                                mb->ya[i][0] *
                                (mb->xa[i][1]-mb->xa[i][0]) /
                                (mb->ya[i][1]-mb->ya[i][0]);
                colval(mb->cmax,i) = mb->xa[i][4] +
                                (1.-mb->ya[i][4]) *
                                (mb->xa[i][5] - mb->xa[i][4]) /
                                (mb->ya[i][5] - mb->ya[i][4]);
        }
}
Revision:	3.19
Committed:	Wed Sep 11 18:56:11 2024 UTC (7 months, 3 weeks ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	HEAD
Changes since 3.18:	+3 -2 lines
Log Message:	feat(pcond,pvalue): Added hyperspectral input handling
#	User	Rev	Content
1	greg	3.1	#ifndef lint
2	greg	3.19	static const char RCSid[] = "$Id: pcond2.c,v 3.18 2015/08/21 05:48:28 greg Exp $";
3	greg	3.1	#endif
4			/*
5			* Input and output conditioning routines for pcond.
6	greg	3.10	* Added white-balance adjustment 10/01 (GW).
7	greg	3.1	*/
8
9			#include "pcond.h"
10	greg	3.8	#include "warp3d.h"
11	greg	3.1
12
13			RGBPRIMP inprims = stdprims; /* input primaries */
14			COLORMAT inrgb2xyz; /* convert input RGB to XYZ */
15			RGBPRIMP outprims = stdprims; /* output primaries */
16
17			double (lumf)() = rgblum; / input luminance function */
18			double inpexp = 1.0; /* input exposure value */
19
20			char mbcalfile = NULL; / macbethcal mapping file */
21	greg	3.8	char cwarpfile = NULL; / color space warping file */
22	greg	3.1
23	greg	3.3	static struct mbc {
24	greg	3.7	COLORMAT cmat;
25	greg	3.3	float xa[3][6], ya[3][6];
26	greg	3.7	COLOR cmin, cmax;
27	greg	3.3	} mbcond; /* macbethcal conditioning struct */
28	greg	3.1
29	greg	3.8	static WARP3D cwarp; / color warping structure */
30
31	greg	3.1	static COLOR scanbuf; / scanline processing buffer */
32			static int nread; /* number of scanlines processed */
33
34	schorsch	3.12	static void sfscan(COLOR *sl, int len, double sf);
35			static void matscan(COLOR *sl, int len, COLORMAT mat);
36			static void mbscan(COLOR sl, int len, struct mbc mb);
37			static void cwscan(COLOR sl, int len, WARP3D wp);
38			static void getmbcalfile(char fn, struct mbc mb);
39	greg	3.1
40	schorsch	3.12
41	greg	3.18	double
42	schorsch	3.12	rgblum( /* compute (scotopic) luminance of RGB color */
43			COLOR clr,
44			int scotopic
45			)
46	greg	3.1	{
47			if (scotopic) /* approximate */
48			return( WHTSEFFICACY * (colval(clr,RED)*.062 +
49			colval(clr,GRN).608 + colval(clr,BLU).330) );
50			return( WHTEFFICACY * (colval(clr,RED)*inrgb2xyz[1][0] +
51			colval(clr,GRN)*inrgb2xyz[1][1] +
52			colval(clr,BLU)*inrgb2xyz[1][2]) );
53			}
54
55
56	greg	3.18	double
57	schorsch	3.12	cielum( /* compute (scotopic) luminance of CIE color */
58			COLOR xyz,
59			int scotopic
60			)
61	greg	3.1	{
62			if (scotopic) /* approximate */
63			return(colval(xyz,CIEY) *
64			(1.33*(1. + (colval(xyz,CIEY)+colval(xyz,CIEZ))/
65			colval(xyz,CIEX)) - 1.68));
66			return(colval(xyz,CIEY));
67			}
68
69
70	greg	3.18	COLOR *
71	schorsch	3.12	nextscan(void) /* read and condition next scanline */
72	greg	3.1	{
73			if (nread >= numscans(&inpres)) {
74	greg	3.8	if (cwarpfile != NULL)
75			free3dw(cwarp);
76	greg	3.10	free((void *)scanbuf);
77	greg	3.4	return(scanbuf = NULL);
78	greg	3.1	}
79	greg	3.2	if (what2do&DO_ACUITY)
80			acuscan(scanbuf, nread);
81	greg	3.19	else if (fread2scan(scanbuf, scanlen(&inpres), infp,
82			NCSAMP, WLPART) < 0) {
83	greg	3.1	fprintf(stderr, "%s: %s: scanline read error\n",
84			progname, infn);
85			exit(1);
86			}
87			if (what2do&DO_VEIL) /* add veiling */
88	greg	3.2	addveil(scanbuf, nread);
89	greg	3.1	if (what2do&DO_COLOR) /* scotopic color loss */
90			scotscan(scanbuf, scanlen(&inpres));
91			if (what2do&DO_LINEAR) /* map luminances */
92			sfscan(scanbuf, scanlen(&inpres), scalef);
93			else
94			mapscan(scanbuf, scanlen(&inpres));
95			if (mbcalfile != NULL) /* device color correction */
96			mbscan(scanbuf, scanlen(&inpres), &mbcond);
97	greg	3.8	else if (cwarpfile != NULL) /* device color space warp */
98			cwscan(scanbuf, scanlen(&inpres), cwarp);
99	schorsch	3.11	else if ((lumf == cielum) \| (inprims != outprims))
100	greg	3.1	matscan(scanbuf, scanlen(&inpres), mbcond.cmat);
101	greg	3.2	nread++;
102	greg	3.1	return(scanbuf);
103			}
104
105
106	greg	3.18	COLOR *
107	schorsch	3.12	firstscan(void) /* return first processed scanline */
108	greg	3.1	{
109			if (mbcalfile != NULL) /* load macbethcal file */
110			getmbcalfile(mbcalfile, &mbcond);
111	greg	3.8	else if (cwarpfile != NULL) {
112			if ((cwarp = load3dw(cwarpfile, NULL)) == NULL)
113			syserror(cwarpfile);
114			} else
115	greg	3.1	if (lumf == rgblum)
116	greg	3.10	comprgb2rgbWBmat(mbcond.cmat, inprims, outprims);
117	greg	3.1	else
118	greg	3.10	compxyz2rgbWBmat(mbcond.cmat, outprims);
119	greg	3.14	if (what2do&DO_ACUITY)
120			initacuity();
121	greg	3.1	scanbuf = (COLOR )malloc(scanlen(&inpres)sizeof(COLOR));
122			if (scanbuf == NULL)
123			syserror("malloc");
124			nread = 0;
125			return(nextscan());
126			}
127
128
129	schorsch	3.12	static void
130			sfscan( /* apply scalefactor to scanline */
131	greg	3.18	COLOR *sl,
132	schorsch	3.12	int len,
133			double sf
134			)
135	greg	3.1	{
136			while (len--) {
137			scalecolor(sl[0], sf);
138			sl++;
139			}
140			}
141
142
143	greg	3.15	static double
144			greypoint( /* compute gamut mapping grey target */
145			COLOR col
146			)
147			{
148			COLOR gryc;
149			int i;
150			/* improves saturated color rendering */
151			copycolor(gryc, col);
152			for (i = 3; i--; )
153	greg	3.17	if (gryc[i] > 1)
154			gryc[i] = 1;
155			else if (gryc[i] < 0)
156			gryc[i] = 0;
157			return(bright(gryc));
158	greg	3.15	}
159
160
161	schorsch	3.12	static void
162			matscan( /* apply color matrix to scaline */
163	greg	3.18	COLOR *sl,
164	schorsch	3.12	int len,
165			COLORMAT mat
166			)
167	greg	3.1	{
168			while (len--) {
169			colortrans(sl[0], mat, sl[0]);
170	greg	3.17	clipgamut(sl[0], greypoint(sl[0]), CGAMUT, cblack, cwhite);
171	greg	3.1	sl++;
172			}
173			}
174
175
176	schorsch	3.12	static void
177			mbscan( /* apply macbethcal adj. to scaline */
178			COLOR *sl,
179			int len,
180	greg	3.18	struct mbc *mb
181	schorsch	3.12	)
182	greg	3.1	{
183			double d;
184	greg	3.18	int i, j;
185	greg	3.1
186			while (len--) {
187	greg	3.6	colortrans(sl[0], mb->cmat, sl[0]);
188	greg	3.17	clipgamut(sl[0], greypoint(sl[0]), CGAMUT, mb->cmin, mb->cmax);
189	greg	3.1	for (i = 0; i < 3; i++) {
190			d = colval(sl[0],i);
191			for (j = 0; j < 4 && mb->xa[i][j+1] <= d; j++)
192			;
193			colval(sl[0],i) = ( (mb->xa[i][j+1] - d)*mb->ya[i][j] +
194			(d - mb->xa[i][j])*mb->ya[i][j+1] ) /
195			(mb->xa[i][j+1] - mb->xa[i][j]);
196			}
197	greg	3.8	sl++;
198			}
199			}
200
201
202	schorsch	3.12	static void
203			cwscan( /* apply color space warp to scaline */
204			COLOR *sl,
205			int len,
206			WARP3D *wp
207			)
208	greg	3.8	{
209			int rval;
210
211			while (len--) {
212			rval = warp3d(sl[0], sl[0], wp);
213			if (rval & W3ERROR)
214			syserror("warp3d");
215			if (rval & W3BADMAP) {
216			fprintf(stderr, "%s: %s: bad color space map\n",
217			progname, cwarpfile);
218			exit(1);
219			}
220	greg	3.17	clipgamut(sl[0], greypoint(sl[0]), CGAMUT, cblack, cwhite);
221	greg	3.1	sl++;
222			}
223			}
224
225
226	schorsch	3.12	static void
227			getmbcalfile( /* load macbethcal file */
228			char *fn,
229	greg	3.18	struct mbc *mb
230	schorsch	3.12	)
231	greg	3.1	{
232			char buf[128];
233			FILE *fp;
234			int inpflags = 0;
235	greg	3.18	int i;
236	greg	3.1
237			if ((fp = fopen(fn, "r")) == NULL)
238			syserror(fn);
239			while (fgets(buf, sizeof(buf), fp) != NULL) {
240			if (!(inpflags & 01) &&
241			sscanf(buf,
242			"rxa(i) : select(i,%f,%f,%f,%f,%f,%f)",
243			&mb->xa[0][0], &mb->xa[0][1],
244			&mb->xa[0][2], &mb->xa[0][3],
245			&mb->xa[0][4], &mb->xa[0][5]
246			) == 6)
247			inpflags \|= 01;
248			else if (!(inpflags & 02) &&
249			sscanf(buf,
250			"rya(i) : select(i,%f,%f,%f,%f,%f,%f)",
251			&mb->ya[0][0], &mb->ya[0][1],
252			&mb->ya[0][2], &mb->ya[0][3],
253			&mb->ya[0][4], &mb->ya[0][5]
254			) == 6)
255			inpflags \|= 02;
256			else if (!(inpflags & 04) &&
257			sscanf(buf,
258			"gxa(i) : select(i,%f,%f,%f,%f,%f,%f)",
259			&mb->xa[1][0], &mb->xa[1][1],
260			&mb->xa[1][2], &mb->xa[1][3],
261			&mb->xa[1][4], &mb->xa[1][5]
262			) == 6)
263			inpflags \|= 04;
264			else if (!(inpflags & 010) &&
265			sscanf(buf,
266			"gya(i) : select(i,%f,%f,%f,%f,%f,%f)",
267			&mb->ya[1][0], &mb->ya[1][1],
268			&mb->ya[1][2], &mb->ya[1][3],
269			&mb->ya[1][4], &mb->ya[1][5]
270			) == 6)
271			inpflags \|= 010;
272			else if (!(inpflags & 020) &&
273			sscanf(buf,
274			"bxa(i) : select(i,%f,%f,%f,%f,%f,%f)",
275			&mb->xa[2][0], &mb->xa[2][1],
276			&mb->xa[2][2], &mb->xa[2][3],
277			&mb->xa[2][4], &mb->xa[2][5]
278			) == 6)
279			inpflags \|= 020;
280			else if (!(inpflags & 040) &&
281			sscanf(buf,
282			"bya(i) : select(i,%f,%f,%f,%f,%f,%f)",
283			&mb->ya[2][0], &mb->ya[2][1],
284			&mb->ya[2][2], &mb->ya[2][3],
285			&mb->ya[2][4], &mb->ya[2][5]
286			) == 6)
287			inpflags \|= 040;
288			else if (!(inpflags & 0100) &&
289			sscanf(buf,
290	gwlarson	3.9	"ro = %frn + %fgn + %f*bn",
291	greg	3.1	&mb->cmat[0][0], &mb->cmat[0][1],
292			&mb->cmat[0][2]) == 3)
293			inpflags \|= 0100;
294			else if (!(inpflags & 0200) &&
295			sscanf(buf,
296	gwlarson	3.9	"go = %frn + %fgn + %f*bn",
297	greg	3.1	&mb->cmat[1][0], &mb->cmat[1][1],
298			&mb->cmat[1][2]) == 3)
299			inpflags \|= 0200;
300			else if (!(inpflags & 0400) &&
301			sscanf(buf,
302	gwlarson	3.9	"bo = %frn + %fgn + %f*bn",
303	greg	3.1	&mb->cmat[2][0], &mb->cmat[2][1],
304			&mb->cmat[2][2]) == 3)
305			inpflags \|= 0400;
306			}
307			if (inpflags != 0777) {
308			fprintf(stderr,
309			"%s: cannot grok macbethcal file \"%s\" (inpflags==0%o)\n",
310			progname, fn, inpflags);
311			exit(1);
312			}
313			fclose(fp);
314	greg	3.7	/* compute gamut */
315			for (i = 0; i < 3; i++) {
316			colval(mb->cmin,i) = mb->xa[i][0] -
317			mb->ya[i][0] *
318			(mb->xa[i][1]-mb->xa[i][0]) /
319			(mb->ya[i][1]-mb->ya[i][0]);
320			colval(mb->cmax,i) = mb->xa[i][4] +
321			(1.-mb->ya[i][4]) *
322			(mb->xa[i][5] - mb->xa[i][4]) /
323			(mb->ya[i][5] - mb->ya[i][4]);
324			}
325	greg	3.1	}