src/gen/mkillum4.c

#ifndef lint
static const char RCSid[] = "$Id: mkillum4.c,v 2.16 2009/05/28 18:38:52 greg Exp $";
#endif
/*
 * Routines for handling BSDF data within mkillum
 */

#include "mkillum.h"
#include "paths.h"
#include "ezxml.h"
#include <ctype.h>

#define MAXLATS         46              /* maximum number of latitudes */

/* BSDF angle specification */
typedef struct {
        char    name[64];               /* basis name */
        int     nangles;                /* total number of directions */
        struct {
                float   tmin;                   /* starting theta */
                short   nphis;                  /* number of phis (0 term) */
        }       lat[MAXLATS+1];         /* latitudes */
} ANGLE_BASIS;

#define MAXABASES       3               /* limit on defined bases */

static ANGLE_BASIS      abase_list[MAXABASES] = {
        {
                "LBNL/Klems Full", 145,
                { {-5., 1},
                {5., 8},
                {15., 16},
                {25., 20},
                {35., 24},
                {45., 24},
                {55., 24},
                {65., 16},
                {75., 12},
                {90., 0} }
        }, {
                "LBNL/Klems Half", 73,
                { {-6.5, 1},
                {6.5, 8},
                {19.5, 12},
                {32.5, 16},
                {46.5, 20},
                {61.5, 12},
                {76.5, 4},
                {90., 0} }
        }, {
                "LBNL/Klems Quarter", 41,
                { {-9., 1},
                {9., 8},
                {27., 12},
                {46., 12},
                {66., 8},
                {90., 0} }
        }
};

static int      nabases = 3;    /* current number of defined bases */


static int
ab_getvec(              /* get vector for this angle basis index */
        FVECT v,
        int ndx,
        void *p
)
{
        ANGLE_BASIS  *ab = (ANGLE_BASIS *)p;
        int     li;
        double  alt, azi, d;
        
        if ((ndx < 0) | (ndx >= ab->nangles))
                return(0);
        for (li = 0; ndx >= ab->lat[li].nphis; li++)
                ndx -= ab->lat[li].nphis;
        alt = PI/180.*0.5*(ab->lat[li].tmin + ab->lat[li+1].tmin);
        azi = 2.*PI*ndx/ab->lat[li].nphis;
        v[2] = d = cos(alt);
        d = sqrt(1. - d*d);     /* sin(alt) */
        v[0] = cos(azi)*d;
        v[1] = sin(azi)*d;
        return(1);
}


static int
ab_getndx(              /* get index corresponding to the given vector */
        FVECT v,
        void *p
)
{
        ANGLE_BASIS  *ab = (ANGLE_BASIS *)p;
        int     li, ndx;
        double  alt, azi, d;

        if ((v[2] < -1.0) | (v[2] > 1.0))
                return(-1);
        alt = 180.0/PI*acos(v[2]);
        azi = 180.0/PI*atan2(v[1], v[0]);
        if (azi < 0.0) azi += 360.0;
        for (li = 1; ab->lat[li].tmin <= alt; li++)
                if (!ab->lat[li].nphis)
                        return(-1);
        --li;
        ndx = (int)((1./360.)*azi*ab->lat[li].nphis + 0.5);
        if (ndx >= ab->lat[li].nphis) ndx = 0;
        while (li--)
                ndx += ab->lat[li].nphis;
        return(ndx);
}


static double
ab_getohm(              /* get solid angle for this angle basis index */
        int ndx,
        void *p
)
{
        ANGLE_BASIS  *ab = (ANGLE_BASIS *)p;
        int     li;
        double  theta, theta1;
        
        if ((ndx < 0) | (ndx >= ab->nangles))
                return(0);
        for (li = 0; ndx >= ab->lat[li].nphis; li++)
                ndx -= ab->lat[li].nphis;
        theta1 = PI/180. * ab->lat[li+1].tmin;
        if (ab->lat[li].nphis == 1) {           /* special case */
                if (ab->lat[li].tmin > FTINY)
                        error(USER, "unsupported BSDF coordinate system");
                return(2.*PI*(1. - cos(theta1)));
        }
        theta = PI/180. * ab->lat[li].tmin;
        return(2.*PI*(cos(theta) - cos(theta1))/(double)ab->lat[li].nphis);
}


static int
ab_getvecR(             /* get reverse vector for this angle basis index */
        FVECT v,
        int ndx,
        void *p
)
{
        if (!ab_getvec(v, ndx, p))
                return(0);

        v[0] = -v[0];
        v[1] = -v[1];
        v[2] = -v[2];

        return(1);
}


static int
ab_getndxR(             /* get index corresponding to the reverse vector */
        FVECT v,
        void *p
)
{
        FVECT  v2;
        
        v2[0] = -v[0];
        v2[1] = -v[1];
        v2[2] = -v[2];

        return ab_getndx(v2, p);
}


static void
load_bsdf_data(         /* load BSDF distribution for this wavelength */
        struct BSDF_data *dp,
        ezxml_t wdb
)
{
        char  *cbasis = ezxml_txt(ezxml_child(wdb,"ColumnAngleBasis"));
        char  *rbasis = ezxml_txt(ezxml_child(wdb,"RowAngleBasis"));
        char  *sdata;
        int  i;
        
        if ((cbasis == NULL) | (rbasis == NULL)) {
                error(WARNING, "missing column/row basis for BSDF");
                return;
        }
        /* XXX need to add routines for loading in foreign bases */
        for (i = nabases; i--; )
                if (!strcmp(cbasis, abase_list[i].name)) {
                        dp->ninc = abase_list[i].nangles;
                        dp->ib_priv = (void *)&abase_list[i];
                        dp->ib_vec = ab_getvecR;
                        dp->ib_ndx = ab_getndxR;
                        dp->ib_ohm = ab_getohm;
                        break;
                }
        if (i < 0) {
                sprintf(errmsg, "unsupported ColumnAngleBasis '%s'", cbasis);
                error(WARNING, errmsg);
                return;
        }
        for (i = nabases; i--; )
                if (!strcmp(rbasis, abase_list[i].name)) {
                        dp->nout = abase_list[i].nangles;
                        dp->ob_priv = (void *)&abase_list[i];
                        dp->ob_vec = ab_getvec;
                        dp->ob_ndx = ab_getndx;
                        dp->ob_ohm = ab_getohm;
                        break;
                }
        if (i < 0) {
                sprintf(errmsg, "unsupported RowAngleBasis '%s'", cbasis);
                error(WARNING, errmsg);
                return;
        }
                                /* read BSDF data */
        sdata  = ezxml_txt(ezxml_child(wdb,"ScatteringData"));
        if (sdata == NULL) {
                error(WARNING, "missing BSDF ScatteringData");
                return;
        }
        dp->bsdf = (float *)malloc(sizeof(float)*dp->ninc*dp->nout);
        if (dp->bsdf == NULL)
                error(SYSTEM, "out of memory in load_bsdf_data");
        for (i = 0; i < dp->ninc*dp->nout; i++) {
                char  *sdnext = fskip(sdata);
                if (sdnext == NULL) {
                        error(WARNING, "bad/missing BSDF ScatteringData");
                        free(dp->bsdf); dp->bsdf = NULL;
                        return;
                }
                while (*sdnext && isspace(*sdnext))
                        sdnext++;
                if (*sdnext == ',') sdnext++;
                dp->bsdf[i] = atof(sdata);
                sdata = sdnext;
        }
        while (isspace(*sdata))
                sdata++;
        if (*sdata) {
                sprintf(errmsg, "%d extra characters after BSDF ScatteringData",
                                strlen(sdata));
                error(WARNING, errmsg);
        }
}


static int
check_bsdf_data(        /* check that BSDF data is sane */
        struct BSDF_data *dp
)
{
        double *        omega_arr;
        double          dom, hemi_total;
        int             nneg;
        int             i, o;

        if (dp == NULL || dp->bsdf == NULL)
                return(0);
        omega_arr = (double *)calloc(dp->nout, sizeof(double));
        if (omega_arr == NULL)
                error(SYSTEM, "out of memory in check_bsdf_data");
        hemi_total = .0;
        for (o = dp->nout; o--; ) {
                FVECT   v;
                dom = getBSDF_outohm(dp,o);
                if (dom <= .0) {
                        error(WARNING, "zero/negative solid angle");
                        continue;
                }
                if (!getBSDF_outvec(v,dp,o) || v[2] < -FTINY) {
                        error(WARNING, "illegal outgoing BSDF direction");
                        free(omega_arr);
                        return(0);
                }
                hemi_total += omega_arr[o] = dom*v[2];
        }
        if ((hemi_total > 1.02*PI) | (hemi_total < 0.98*PI)) {
                sprintf(errmsg, "outgoing BSDF hemisphere off by %.1f%%",
                                100.*(hemi_total/PI - 1.));
                error(WARNING, errmsg);
        }
        dom = PI / hemi_total;          /* normalize solid angles */
        for (o = dp->nout; o--; )
                omega_arr[o] *= dom;
        nneg = 0;
        for (i = dp->ninc; i--; ) {
                hemi_total = .0;
                for (o = dp->nout; o--; ) {
                        double  f = BSDF_value(dp,i,o);
                        if (f > .0)
                                hemi_total += f*omega_arr[o];
                        else if (f < -FTINY)
                                ++nneg;
                }
                if (hemi_total > 1.02) {
                        sprintf(errmsg, "BSDF direction passes %.1f%% of light",
                                        100.*hemi_total);
                        error(WARNING, errmsg);
                }
        }
        free(omega_arr);
        if (nneg > 0) {
                sprintf(errmsg, "%d negative BSDF values", nneg);
                error(WARNING, errmsg);
                return(0);
        }
        return(1);
}

struct BSDF_data *
load_BSDF(              /* load BSDF data from file */
        char *fname
)
{
        char                    *path;
        ezxml_t                 fl, wtl, wld, wdb;
        struct BSDF_data        *dp;
        
        path = getpath(fname, getrlibpath(), R_OK);
        if (path == NULL) {
                sprintf(errmsg, "cannot find BSDF file \"%s\"", fname);
                error(WARNING, errmsg);
                return(NULL);
        }
        fl = ezxml_parse_file(path);
        if (fl == NULL) {
                sprintf(errmsg, "cannot open BSDF \"%s\"", path);
                error(WARNING, errmsg);
                return(NULL);
        }
        if (ezxml_error(fl)[0]) {
                sprintf(errmsg, "BSDF \"%s\" %s", path, ezxml_error(fl));
                error(WARNING, errmsg);
                ezxml_free(fl);
                return(NULL);
        }
        if (strcmp(ezxml_name(fl), "WindowElement")) {
                sprintf(errmsg,
                        "BSDF \"%s\": top level node not 'WindowElement'",
                                path);
                error(WARNING, errmsg);
                ezxml_free(fl);
                return(NULL);
        }
        wtl = ezxml_child(ezxml_child(fl, "Optical"), "Layer");
        dp = (struct BSDF_data *)calloc(1, sizeof(struct BSDF_data));
        for (wld = ezxml_child(wtl, "WavelengthData");
                                wld != NULL; wld = wld->next) {
                if (strcmp(ezxml_txt(ezxml_child(wld,"Wavelength")), "Visible"))
                        continue;
                wdb = ezxml_child(wld, "WavelengthDataBlock");
                if (wdb == NULL) continue;
                if (strcmp(ezxml_txt(ezxml_child(wdb,"WavelengthDataDirection")),
                                        "Transmission Front"))
                        continue;
                load_bsdf_data(dp, wdb);        /* load front BTDF */
                break;                          /* ignore the rest */
        }
        ezxml_free(fl);                         /* done with XML file */
        if (!check_bsdf_data(dp)) {
                sprintf(errmsg, "bad/missing BTDF data in \"%s\"", path);
                error(WARNING, errmsg);
                free_BSDF(dp);
                dp = NULL;
        }
        return(dp);
}


void
free_BSDF(              /* free BSDF data structure */
        struct BSDF_data *b
)
{
        if (b == NULL)
                return;
        if (b->bsdf != NULL)
                free(b->bsdf);
        free(b);
}


int
r_BSDF_incvec(          /* compute random input vector at given location */
        FVECT v,
        struct BSDF_data *b,
        int i,
        double rv,
        MAT4 xm
)
{
        FVECT   pert;
        double  rad;
        int     j;
        
        if (!getBSDF_incvec(v, b, i))
                return(0);
        rad = sqrt(getBSDF_incohm(b, i) / PI);
        multisamp(pert, 3, rv);
        for (j = 0; j < 3; j++)
                v[j] += rad*(2.*pert[j] - 1.);
        if (xm != NULL)
                multv3(v, v, xm);
        return(normalize(v) != 0.0);
}


int
r_BSDF_outvec(          /* compute random output vector at given location */
        FVECT v,
        struct BSDF_data *b,
        int o,
        double rv,
        MAT4 xm
)
{
        FVECT   pert;
        double  rad;
        int     j;
        
        if (!getBSDF_outvec(v, b, o))
                return(0);
        rad = sqrt(getBSDF_outohm(b, o) / PI);
        multisamp(pert, 3, rv);
        for (j = 0; j < 3; j++)
                v[j] += rad*(2.*pert[j] - 1.);
        if (xm != NULL)
                multv3(v, v, xm);
        return(normalize(v) != 0.0);
}


#define  FEQ(a,b)       ((a)-(b) <= 1e-7 && (b)-(a) <= 1e-7)

static int
addrot(                 /* compute rotation (x,y,z) => (xp,yp,zp) */
        char *xfarg[],
        FVECT xp,
        FVECT yp,
        FVECT zp
)
{
        static char     bufs[3][16];
        int     bn = 0;
        char    **xfp = xfarg;
        double  theta;

        if (yp[2]*yp[2] + zp[2]*zp[2] < 2.*FTINY*FTINY) {
                /* Special case for X' along Z-axis */
                theta = -atan2(yp[0], yp[1]);
                *xfp++ = "-ry";
                *xfp++ = xp[2] < 0.0 ? "90" : "-90";
                *xfp++ = "-rz";
                sprintf(bufs[bn], "%f", theta*(180./PI));
                *xfp++ = bufs[bn++];
                return(xfp - xfarg);
        }
        theta = atan2(yp[2], zp[2]);
        if (!FEQ(theta,0.0)) {
                *xfp++ = "-rx";
                sprintf(bufs[bn], "%f", theta*(180./PI));
                *xfp++ = bufs[bn++];
        }
        theta = asin(-xp[2]);
        if (!FEQ(theta,0.0)) {
                *xfp++ = "-ry";
                sprintf(bufs[bn], " %f", theta*(180./PI));
                *xfp++ = bufs[bn++];
        }
        theta = atan2(xp[1], xp[0]);
        if (!FEQ(theta,0.0)) {
                *xfp++ = "-rz";
                sprintf(bufs[bn], "%f", theta*(180./PI));
                *xfp++ = bufs[bn++];
        }
        *xfp = NULL;
        return(xfp - xfarg);
}


int
getBSDF_xfm(            /* compute BSDF orient. -> world orient. transform */
        MAT4 xm,
        FVECT nrm,
        UpDir ud
)
{
        char    *xfargs[7];
        XF      myxf;
        FVECT   updir, xdest, ydest;

        updir[0] = updir[1] = updir[2] = 0.;
        switch (ud) {
        case UDzneg:
                updir[2] = -1.;
                break;
        case UDyneg:
                updir[1] = -1.;
                break;
        case UDxneg:
                updir[0] = -1.;
                break;
        case UDxpos:
                updir[0] = 1.;
                break;
        case UDypos:
                updir[1] = 1.;
                break;
        case UDzpos:
                updir[2] = 1.;
                break;
        case UDunknown:
                return(0);
        }
        fcross(xdest, updir, nrm);
        if (normalize(xdest) == 0.0)
                return(0);
        fcross(ydest, nrm, xdest);
        xf(&myxf, addrot(xfargs, xdest, ydest, nrm), xfargs);
        copymat4(xm, myxf.xfm);
        return(1);
}


void
redistribute(           /* pass distarr ray sums through BSDF */
        struct BSDF_data *b,
        int nalt,
        int nazi,
        FVECT u,
        FVECT v,
        FVECT w,
        MAT4 xm
)
{
        int     nout = 0;
        MAT4    mymat, inmat;
        COLORV  *idist;
        COLORV  *cp;
        FVECT   dv;
        double  wt;
        int     i, j, k, o;
        COLOR   col, cinc;
                                        /* copy incoming distribution */
        if (b->ninc > distsiz)
                error(INTERNAL, "error 1 in redistribute");
        idist = (COLORV *)malloc(sizeof(COLOR)*b->ninc);
        if (idist == NULL)
                error(SYSTEM, "out of memory in redistribute");
        memcpy(idist, distarr, sizeof(COLOR)*b->ninc);
                                        /* compose direction transform */
        for (i = 3; i--; ) {
                mymat[i][0] = u[i];
                mymat[i][1] = v[i];
                mymat[i][2] = w[i];
                mymat[i][3] = 0.;
        }
        mymat[3][0] = mymat[3][1] = mymat[3][2] = 0.;
        mymat[3][3] = 1.;
        if (xm != NULL)
                multmat4(mymat, xm, mymat);
        for (i = 3; i--; ) {            /* make sure it's normalized */
                wt = 1./sqrt(   mymat[0][i]*mymat[0][i] +
                                mymat[1][i]*mymat[1][i] +
                                mymat[2][i]*mymat[2][i] );
                for (j = 3; j--; )
                        mymat[j][i] *= wt;
        }
        if (!invmat4(inmat, mymat))     /* need inverse as well */
                error(INTERNAL, "cannot invert BSDF transform");
        newdist(nalt*nazi);             /* resample distribution */
        for (i = b->ninc; i--; ) {
                int     direct_out = -1;
                COLOR   cdir;
                getBSDF_incvec(dv, b, i);       /* compute incident irrad. */
                multv3(dv, dv, mymat);
                if (dv[2] < 0.0) {
                        dv[0] = -dv[0]; dv[1] = -dv[1]; dv[2] = -dv[2];
                        direct_out += (direct_discount != NULL);
                }
                wt = getBSDF_incohm(b, i);
                wt *= dv[2];                    /* solid_angle*cosine(theta) */
                cp = &idist[3*i];
                copycolor(cinc, cp);
                scalecolor(cinc, wt);
                if (!direct_out) {              /* discount direct contr. */
                        cp = &direct_discount[3*i];
                        copycolor(cdir, cp);
                        scalecolor(cdir, -wt);
                        direct_out = flatindex(dv, nalt, nazi);
                }
                for (k = nalt; k--; )           /* loop over distribution */
                    for (j = nazi; j--; ) {
                        flatdir(dv, (k + .5)/nalt, (double)j/nazi);
                        multv3(dv, dv, inmat);
                                                /* evaluate BSDF @ outgoing */
                        o = getBSDF_outndx(b, dv);
                        if (o < 0) {
                                nout++;
                                continue;
                        }
                        wt = BSDF_value(b, i, o);
                        copycolor(col, cinc);
                        o = k*nazi + j;
                        if (o == direct_out)
                                addcolor(col, cdir);    /* minus direct */
                        scalecolor(col, wt);
                        cp = &distarr[3*o];
                        addcolor(cp, col);      /* sum into distribution */
                    }
        }
        free(idist);                    /* free temp space */
        if (nout) {
                sprintf(errmsg, "missing %.1f%% of BSDF directions",
                                100.*nout/(b->ninc*nalt*nazi));
                error(WARNING, errmsg);
        }
}
Revision:	2.17
Committed:	Sat May 30 22:19:08 2009 UTC (16 years, 5 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.16:	+70 -10 lines
Log Message:	Fixed bug in solid angle calculation and added BSDF checks
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.17	static const char RCSid[] = "$Id: mkillum4.c,v 2.16 2009/05/28 18:38:52 greg Exp $";
3	greg	2.1	#endif
4			/*
5			* Routines for handling BSDF data within mkillum
6			*/
7
8			#include "mkillum.h"
9			#include "paths.h"
10	greg	2.2	#include "ezxml.h"
11	greg	2.12	#include <ctype.h>
12	greg	2.1
13	greg	2.6	#define MAXLATS 46 /* maximum number of latitudes */
14
15	greg	2.11	/* BSDF angle specification */
16	greg	2.6	typedef struct {
17	greg	2.7	char name[64]; /* basis name */
18	greg	2.6	int nangles; /* total number of directions */
19			struct {
20			float tmin; /* starting theta */
21			short nphis; /* number of phis (0 term) */
22			} lat[MAXLATS+1]; /* latitudes */
23			} ANGLE_BASIS;
24
25	greg	2.7	#define MAXABASES 3 /* limit on defined bases */
26	greg	2.6
27	greg	2.13	static ANGLE_BASIS abase_list[MAXABASES] = {
28	greg	2.6	{
29			"LBNL/Klems Full", 145,
30			{ {-5., 1},
31			{5., 8},
32			{15., 16},
33			{25., 20},
34			{35., 24},
35			{45., 24},
36			{55., 24},
37			{65., 16},
38			{75., 12},
39			{90., 0} }
40			}, {
41			"LBNL/Klems Half", 73,
42			{ {-6.5, 1},
43			{6.5, 8},
44			{19.5, 12},
45			{32.5, 16},
46			{46.5, 20},
47			{61.5, 12},
48			{76.5, 4},
49			{90., 0} }
50			}, {
51			"LBNL/Klems Quarter", 41,
52			{ {-9., 1},
53			{9., 8},
54			{27., 12},
55			{46., 12},
56			{66., 8},
57			{90., 0} }
58			}
59			};
60
61	greg	2.7	static int nabases = 3; /* current number of defined bases */
62
63	greg	2.6
64			static int
65			ab_getvec( /* get vector for this angle basis index */
66			FVECT v,
67			int ndx,
68			void *p
69			)
70			{
71			ANGLE_BASIS ab = (ANGLE_BASIS )p;
72			int li;
73			double alt, azi, d;
74
75			if ((ndx < 0) \| (ndx >= ab->nangles))
76			return(0);
77			for (li = 0; ndx >= ab->lat[li].nphis; li++)
78			ndx -= ab->lat[li].nphis;
79			alt = PI/180.0.5(ab->lat[li].tmin + ab->lat[li+1].tmin);
80			azi = 2.PIndx/ab->lat[li].nphis;
81	greg	2.11	v[2] = d = cos(alt);
82			d = sqrt(1. - dd); / sin(alt) */
83	greg	2.6	v[0] = cos(azi)*d;
84			v[1] = sin(azi)*d;
85			return(1);
86			}
87
88
89			static int
90			ab_getndx( /* get index corresponding to the given vector */
91			FVECT v,
92			void *p
93			)
94			{
95			ANGLE_BASIS ab = (ANGLE_BASIS )p;
96			int li, ndx;
97			double alt, azi, d;
98
99	greg	2.7	if ((v[2] < -1.0) \| (v[2] > 1.0))
100	greg	2.6	return(-1);
101			alt = 180.0/PI*acos(v[2]);
102			azi = 180.0/PI*atan2(v[1], v[0]);
103			if (azi < 0.0) azi += 360.0;
104			for (li = 1; ab->lat[li].tmin <= alt; li++)
105			if (!ab->lat[li].nphis)
106			return(-1);
107			--li;
108			ndx = (int)((1./360.)aziab->lat[li].nphis + 0.5);
109			if (ndx >= ab->lat[li].nphis) ndx = 0;
110			while (li--)
111			ndx += ab->lat[li].nphis;
112			return(ndx);
113			}
114
115
116			static double
117			ab_getohm( /* get solid angle for this angle basis index */
118			int ndx,
119			void *p
120			)
121			{
122			ANGLE_BASIS ab = (ANGLE_BASIS )p;
123			int li;
124	greg	2.17	double theta, theta1;
125	greg	2.6
126			if ((ndx < 0) \| (ndx >= ab->nangles))
127			return(0);
128			for (li = 0; ndx >= ab->lat[li].nphis; li++)
129			ndx -= ab->lat[li].nphis;
130	greg	2.17	theta1 = PI/180. * ab->lat[li+1].tmin;
131	greg	2.7	if (ab->lat[li].nphis == 1) { /* special case */
132			if (ab->lat[li].tmin > FTINY)
133			error(USER, "unsupported BSDF coordinate system");
134	greg	2.17	return(2.PI(1. - cos(theta1)));
135	greg	2.7	}
136	greg	2.17	theta = PI/180. * ab->lat[li].tmin;
137			return(2.PI(cos(theta) - cos(theta1))/(double)ab->lat[li].nphis);
138	greg	2.6	}
139
140
141			static int
142			ab_getvecR( /* get reverse vector for this angle basis index */
143			FVECT v,
144			int ndx,
145			void *p
146			)
147			{
148			if (!ab_getvec(v, ndx, p))
149			return(0);
150
151			v[0] = -v[0];
152			v[1] = -v[1];
153	greg	2.11	v[2] = -v[2];
154	greg	2.6
155			return(1);
156			}
157
158
159			static int
160			ab_getndxR( /* get index corresponding to the reverse vector */
161			FVECT v,
162			void *p
163			)
164			{
165			FVECT v2;
166
167			v2[0] = -v[0];
168			v2[1] = -v[1];
169	greg	2.11	v2[2] = -v[2];
170	greg	2.6
171			return ab_getndx(v2, p);
172			}
173
174	greg	2.7
175	greg	2.6	static void
176			load_bsdf_data( /* load BSDF distribution for this wavelength */
177			struct BSDF_data *dp,
178			ezxml_t wdb
179			)
180			{
181	greg	2.7	char *cbasis = ezxml_txt(ezxml_child(wdb,"ColumnAngleBasis"));
182			char *rbasis = ezxml_txt(ezxml_child(wdb,"RowAngleBasis"));
183			char *sdata;
184	greg	2.6	int i;
185
186	greg	2.7	if ((cbasis == NULL) \| (rbasis == NULL)) {
187			error(WARNING, "missing column/row basis for BSDF");
188			return;
189			}
190			/* XXX need to add routines for loading in foreign bases */
191			for (i = nabases; i--; )
192	greg	2.6	if (!strcmp(cbasis, abase_list[i].name)) {
193			dp->ninc = abase_list[i].nangles;
194			dp->ib_priv = (void *)&abase_list[i];
195	greg	2.11	dp->ib_vec = ab_getvecR;
196			dp->ib_ndx = ab_getndxR;
197	greg	2.6	dp->ib_ohm = ab_getohm;
198			break;
199			}
200			if (i < 0) {
201	greg	2.7	sprintf(errmsg, "unsupported ColumnAngleBasis '%s'", cbasis);
202			error(WARNING, errmsg);
203			return;
204	greg	2.6	}
205	greg	2.7	for (i = nabases; i--; )
206	greg	2.6	if (!strcmp(rbasis, abase_list[i].name)) {
207			dp->nout = abase_list[i].nangles;
208			dp->ob_priv = (void *)&abase_list[i];
209	greg	2.11	dp->ob_vec = ab_getvec;
210			dp->ob_ndx = ab_getndx;
211	greg	2.6	dp->ob_ohm = ab_getohm;
212			break;
213			}
214			if (i < 0) {
215	greg	2.7	sprintf(errmsg, "unsupported RowAngleBasis '%s'", cbasis);
216			error(WARNING, errmsg);
217			return;
218			}
219			/* read BSDF data */
220			sdata = ezxml_txt(ezxml_child(wdb,"ScatteringData"));
221			if (sdata == NULL) {
222			error(WARNING, "missing BSDF ScatteringData");
223			return;
224			}
225			dp->bsdf = (float )malloc(sizeof(float)dp->ninc*dp->nout);
226			if (dp->bsdf == NULL)
227			error(SYSTEM, "out of memory in load_bsdf_data");
228			for (i = 0; i < dp->ninc*dp->nout; i++) {
229			char *sdnext = fskip(sdata);
230			if (sdnext == NULL) {
231			error(WARNING, "bad/missing BSDF ScatteringData");
232			free(dp->bsdf); dp->bsdf = NULL;
233			return;
234			}
235			while (sdnext && isspace(sdnext))
236			sdnext++;
237			if (*sdnext == ',') sdnext++;
238			dp->bsdf[i] = atof(sdata);
239			sdata = sdnext;
240			}
241			while (isspace(*sdata))
242			sdata++;
243			if (*sdata) {
244			sprintf(errmsg, "%d extra characters after BSDF ScatteringData",
245			strlen(sdata));
246			error(WARNING, errmsg);
247	greg	2.6	}
248			}
249
250	greg	2.1
251	greg	2.17	static int
252			check_bsdf_data( /* check that BSDF data is sane */
253			struct BSDF_data *dp
254			)
255			{
256			double * omega_arr;
257			double dom, hemi_total;
258			int nneg;
259			int i, o;
260
261			if (dp == NULL \|\| dp->bsdf == NULL)
262			return(0);
263			omega_arr = (double *)calloc(dp->nout, sizeof(double));
264			if (omega_arr == NULL)
265			error(SYSTEM, "out of memory in check_bsdf_data");
266			hemi_total = .0;
267			for (o = dp->nout; o--; ) {
268			FVECT v;
269			dom = getBSDF_outohm(dp,o);
270			if (dom <= .0) {
271			error(WARNING, "zero/negative solid angle");
272			continue;
273			}
274			if (!getBSDF_outvec(v,dp,o) \|\| v[2] < -FTINY) {
275			error(WARNING, "illegal outgoing BSDF direction");
276			free(omega_arr);
277			return(0);
278			}
279			hemi_total += omega_arr[o] = dom*v[2];
280			}
281			if ((hemi_total > 1.02PI) \| (hemi_total < 0.98PI)) {
282			sprintf(errmsg, "outgoing BSDF hemisphere off by %.1f%%",
283			100.*(hemi_total/PI - 1.));
284			error(WARNING, errmsg);
285			}
286			dom = PI / hemi_total; /* normalize solid angles */
287			for (o = dp->nout; o--; )
288			omega_arr[o] *= dom;
289			nneg = 0;
290			for (i = dp->ninc; i--; ) {
291			hemi_total = .0;
292			for (o = dp->nout; o--; ) {
293			double f = BSDF_value(dp,i,o);
294			if (f > .0)
295			hemi_total += f*omega_arr[o];
296			else if (f < -FTINY)
297			++nneg;
298			}
299			if (hemi_total > 1.02) {
300			sprintf(errmsg, "BSDF direction passes %.1f%% of light",
301			100.*hemi_total);
302			error(WARNING, errmsg);
303			}
304			}
305			free(omega_arr);
306			if (nneg > 0) {
307			sprintf(errmsg, "%d negative BSDF values", nneg);
308			error(WARNING, errmsg);
309			return(0);
310			}
311			return(1);
312			}
313
314	greg	2.1	struct BSDF_data *
315			load_BSDF( /* load BSDF data from file */
316			char *fname
317			)
318			{
319			char *path;
320	greg	2.10	ezxml_t fl, wtl, wld, wdb;
321	greg	2.1	struct BSDF_data *dp;
322
323			path = getpath(fname, getrlibpath(), R_OK);
324			if (path == NULL) {
325			sprintf(errmsg, "cannot find BSDF file \"%s\"", fname);
326			error(WARNING, errmsg);
327			return(NULL);
328			}
329	greg	2.2	fl = ezxml_parse_file(path);
330			if (fl == NULL) {
331	greg	2.1	sprintf(errmsg, "cannot open BSDF \"%s\"", path);
332			error(WARNING, errmsg);
333			return(NULL);
334			}
335	greg	2.6	if (ezxml_error(fl)[0]) {
336	greg	2.10	sprintf(errmsg, "BSDF \"%s\" %s", path, ezxml_error(fl));
337	greg	2.6	error(WARNING, errmsg);
338			ezxml_free(fl);
339			return(NULL);
340			}
341	greg	2.10	if (strcmp(ezxml_name(fl), "WindowElement")) {
342			sprintf(errmsg,
343			"BSDF \"%s\": top level node not 'WindowElement'",
344			path);
345			error(WARNING, errmsg);
346			ezxml_free(fl);
347			return(NULL);
348			}
349			wtl = ezxml_child(ezxml_child(fl, "Optical"), "Layer");
350	greg	2.5	dp = (struct BSDF_data *)calloc(1, sizeof(struct BSDF_data));
351	greg	2.10	for (wld = ezxml_child(wtl, "WavelengthData");
352	greg	2.8	wld != NULL; wld = wld->next) {
353	greg	2.6	if (strcmp(ezxml_txt(ezxml_child(wld,"Wavelength")), "Visible"))
354	greg	2.2	continue;
355			wdb = ezxml_child(wld, "WavelengthDataBlock");
356			if (wdb == NULL) continue;
357	greg	2.6	if (strcmp(ezxml_txt(ezxml_child(wdb,"WavelengthDataDirection")),
358	greg	2.2	"Transmission Front"))
359			continue;
360	greg	2.6	load_bsdf_data(dp, wdb); /* load front BTDF */
361			break; /* ignore the rest */
362			}
363			ezxml_free(fl); /* done with XML file */
364	greg	2.17	if (!check_bsdf_data(dp)) {
365	greg	2.6	sprintf(errmsg, "bad/missing BTDF data in \"%s\"", path);
366			error(WARNING, errmsg);
367			free_BSDF(dp);
368			dp = NULL;
369	greg	2.2	}
370	greg	2.1	return(dp);
371			}
372
373
374			void
375			free_BSDF( /* free BSDF data structure */
376			struct BSDF_data *b
377			)
378			{
379			if (b == NULL)
380			return;
381	greg	2.6	if (b->bsdf != NULL)
382			free(b->bsdf);
383	greg	2.1	free(b);
384			}
385
386
387	greg	2.6	int
388	greg	2.1	r_BSDF_incvec( /* compute random input vector at given location */
389			FVECT v,
390			struct BSDF_data *b,
391			int i,
392			double rv,
393			MAT4 xm
394			)
395			{
396			FVECT pert;
397			double rad;
398			int j;
399
400	greg	2.6	if (!getBSDF_incvec(v, b, i))
401			return(0);
402			rad = sqrt(getBSDF_incohm(b, i) / PI);
403	greg	2.1	multisamp(pert, 3, rv);
404			for (j = 0; j < 3; j++)
405			v[j] += rad(2.pert[j] - 1.);
406			if (xm != NULL)
407			multv3(v, v, xm);
408	greg	2.7	return(normalize(v) != 0.0);
409	greg	2.1	}
410
411
412	greg	2.6	int
413	greg	2.1	r_BSDF_outvec( /* compute random output vector at given location */
414			FVECT v,
415			struct BSDF_data *b,
416			int o,
417			double rv,
418			MAT4 xm
419			)
420			{
421			FVECT pert;
422			double rad;
423			int j;
424
425	greg	2.6	if (!getBSDF_outvec(v, b, o))
426			return(0);
427			rad = sqrt(getBSDF_outohm(b, o) / PI);
428	greg	2.1	multisamp(pert, 3, rv);
429			for (j = 0; j < 3; j++)
430			v[j] += rad(2.pert[j] - 1.);
431			if (xm != NULL)
432			multv3(v, v, xm);
433	greg	2.7	return(normalize(v) != 0.0);
434	greg	2.1	}
435	greg	2.2
436
437			#define FEQ(a,b) ((a)-(b) <= 1e-7 && (b)-(a) <= 1e-7)
438
439			static int
440			addrot( /* compute rotation (x,y,z) => (xp,yp,zp) */
441			char *xfarg[],
442			FVECT xp,
443			FVECT yp,
444			FVECT zp
445			)
446			{
447			static char bufs[3][16];
448			int bn = 0;
449			char **xfp = xfarg;
450			double theta;
451
452	greg	2.9	if (yp[2]yp[2] + zp[2]zp[2] < 2.FTINYFTINY) {
453			/* Special case for X' along Z-axis */
454			theta = -atan2(yp[0], yp[1]);
455			*xfp++ = "-ry";
456			*xfp++ = xp[2] < 0.0 ? "90" : "-90";
457			*xfp++ = "-rz";
458			sprintf(bufs[bn], "%f", theta*(180./PI));
459			*xfp++ = bufs[bn++];
460			return(xfp - xfarg);
461			}
462	greg	2.2	theta = atan2(yp[2], zp[2]);
463			if (!FEQ(theta,0.0)) {
464			*xfp++ = "-rx";
465			sprintf(bufs[bn], "%f", theta*(180./PI));
466			*xfp++ = bufs[bn++];
467			}
468			theta = asin(-xp[2]);
469			if (!FEQ(theta,0.0)) {
470			*xfp++ = "-ry";
471			sprintf(bufs[bn], " %f", theta*(180./PI));
472			*xfp++ = bufs[bn++];
473			}
474			theta = atan2(xp[1], xp[0]);
475			if (!FEQ(theta,0.0)) {
476			*xfp++ = "-rz";
477			sprintf(bufs[bn], "%f", theta*(180./PI));
478			*xfp++ = bufs[bn++];
479			}
480			*xfp = NULL;
481			return(xfp - xfarg);
482			}
483
484
485			int
486	greg	2.6	getBSDF_xfm( /* compute BSDF orient. -> world orient. transform */
487	greg	2.2	MAT4 xm,
488			FVECT nrm,
489			UpDir ud
490			)
491			{
492			char *xfargs[7];
493			XF myxf;
494			FVECT updir, xdest, ydest;
495
496			updir[0] = updir[1] = updir[2] = 0.;
497			switch (ud) {
498			case UDzneg:
499			updir[2] = -1.;
500			break;
501			case UDyneg:
502			updir[1] = -1.;
503			break;
504			case UDxneg:
505			updir[0] = -1.;
506			break;
507			case UDxpos:
508			updir[0] = 1.;
509			break;
510			case UDypos:
511			updir[1] = 1.;
512			break;
513			case UDzpos:
514			updir[2] = 1.;
515			break;
516			case UDunknown:
517			return(0);
518			}
519			fcross(xdest, updir, nrm);
520			if (normalize(xdest) == 0.0)
521			return(0);
522			fcross(ydest, nrm, xdest);
523			xf(&myxf, addrot(xfargs, xdest, ydest, nrm), xfargs);
524			copymat4(xm, myxf.xfm);
525			return(1);
526			}
527
528
529			void
530			redistribute( /* pass distarr ray sums through BSDF */
531			struct BSDF_data *b,
532			int nalt,
533			int nazi,
534			FVECT u,
535			FVECT v,
536			FVECT w,
537			MAT4 xm
538			)
539			{
540	greg	2.6	int nout = 0;
541	greg	2.5	MAT4 mymat, inmat;
542			COLORV *idist;
543	greg	2.15	COLORV *cp;
544	greg	2.2	FVECT dv;
545	greg	2.5	double wt;
546	greg	2.6	int i, j, k, o;
547	greg	2.5	COLOR col, cinc;
548			/* copy incoming distribution */
549	greg	2.14	if (b->ninc > distsiz)
550	greg	2.5	error(INTERNAL, "error 1 in redistribute");
551	greg	2.14	idist = (COLORV )malloc(sizeof(COLOR)b->ninc);
552	greg	2.5	if (idist == NULL)
553	greg	2.2	error(SYSTEM, "out of memory in redistribute");
554	greg	2.14	memcpy(idist, distarr, sizeof(COLOR)*b->ninc);
555	greg	2.5	/* compose direction transform */
556	greg	2.2	for (i = 3; i--; ) {
557			mymat[i][0] = u[i];
558			mymat[i][1] = v[i];
559			mymat[i][2] = w[i];
560			mymat[i][3] = 0.;
561			}
562			mymat[3][0] = mymat[3][1] = mymat[3][2] = 0.;
563			mymat[3][3] = 1.;
564			if (xm != NULL)
565			multmat4(mymat, xm, mymat);
566			for (i = 3; i--; ) { /* make sure it's normalized */
567	greg	2.5	wt = 1./sqrt( mymat[0][i]*mymat[0][i] +
568	greg	2.2	mymat[1][i]*mymat[1][i] +
569			mymat[2][i]*mymat[2][i] );
570			for (j = 3; j--; )
571	greg	2.5	mymat[j][i] *= wt;
572	greg	2.2	}
573	greg	2.5	if (!invmat4(inmat, mymat)) /* need inverse as well */
574			error(INTERNAL, "cannot invert BSDF transform");
575			newdist(naltnazi); / resample distribution */
576	greg	2.4	for (i = b->ninc; i--; ) {
577	greg	2.15	int direct_out = -1;
578			COLOR cdir;
579	greg	2.5	getBSDF_incvec(dv, b, i); /* compute incident irrad. */
580	greg	2.2	multv3(dv, dv, mymat);
581	greg	2.15	if (dv[2] < 0.0) {
582			dv[0] = -dv[0]; dv[1] = -dv[1]; dv[2] = -dv[2];
583			direct_out += (direct_discount != NULL);
584			}
585	greg	2.6	wt = getBSDF_incohm(b, i);
586			wt = dv[2]; / solid_anglecosine(theta) /
587	greg	2.5	cp = &idist[3*i];
588			copycolor(cinc, cp);
589			scalecolor(cinc, wt);
590	greg	2.15	if (!direct_out) { /* discount direct contr. */
591			cp = &direct_discount[3*i];
592			copycolor(cdir, cp);
593			scalecolor(cdir, -wt);
594			direct_out = flatindex(dv, nalt, nazi);
595			}
596	greg	2.5	for (k = nalt; k--; ) /* loop over distribution */
597			for (j = nazi; j--; ) {
598			flatdir(dv, (k + .5)/nalt, (double)j/nazi);
599			multv3(dv, dv, inmat);
600			/* evaluate BSDF @ outgoing */
601	greg	2.6	o = getBSDF_outndx(b, dv);
602			if (o < 0) {
603			nout++;
604			continue;
605			}
606	greg	2.7	wt = BSDF_value(b, i, o);
607	greg	2.5	copycolor(col, cinc);
608	greg	2.15	o = k*nazi + j;
609			if (o == direct_out)
610			addcolor(col, cdir); /* minus direct */
611	greg	2.5	scalecolor(col, wt);
612	greg	2.15	cp = &distarr[3*o];
613			addcolor(cp, col); /* sum into distribution */
614	greg	2.5	}
615	greg	2.2	}
616	greg	2.5	free(idist); /* free temp space */
617	greg	2.6	if (nout) {
618			sprintf(errmsg, "missing %.1f%% of BSDF directions",
619			100.nout/(b->nincnalt*nazi));
620			error(WARNING, errmsg);
621			}
622	greg	2.2	}