src/rt/m_mist.c

#ifndef lint
static const char RCSid[] = "$Id: m_mist.c,v 2.20 2019/02/13 02:38:26 greg Exp $";
#endif
/*
 * Mist volumetric material.
 */

#include "copyright.h"

#include <string.h>

#include  "ray.h"
#include  "source.h"
#include  "rtotypes.h"

/*
 *  A mist volume is used to specify a region in the scene where a certain
 *  light source (or sources) is going to contribute to scattering.  The
 *  material can add to the existing global medium, and override any ray
 *  settings for scattering albedo and eccentricity.  Overlapping mist
 *  regions should agree w.r.t. albedo and eccentricity, and
 *  should have disjoint source lists.
 *
 *  A pattern, if used, should compute the line integral of extinction,
 *  and will modify the first three arguments directly.  This will tend
 *  to invalidate results when there are other objects intersected within
 *  the mist region.
 *
 *  The string arguments for MAT_MIST are the identifiers for the important
 *  light sources, which will be looked up in the source array.  The last
 *  source found matching a name is the one used.  A relayed light source
 *  may be indicated by the relay surface name, followed by a '>' character,
 *  followed by the relayed source name (which may be another relay).
 *
 *  Up to five real arguments may be given for MAT_MIST:
 *
 *      [ext_r  ext_g  ext_b  [albedo_r albedo_g albedo_b [gecc]]]
 *
 *  The primaries indicate medium extinction per unit length (absorption
 *  plus scattering), which is added to the global extinction coefficient, set
 *  by the -me option.  The albedo is the ratio of scattering to extinction,
 *  and is set globally by the -ma option (salbedo) and overridden here.
 *  The Heyney-Greenstein eccentricity parameter (-mg seccg) indicates how much
 *  scattering favors the forward direction.  A value of 0 means isotropic
 *  scattering.  A value approaching 1 indicates strong forward scattering.
 */

#ifndef  MAXSLIST
#define  MAXSLIST       32      /* maximum sources to check */
#endif

#define RELAYDELIM      '>'             /* relay delimiter character */

static int inslist(int  *sl, int  n);
static int srcmatch(SRCREC  *sp, char  *id);
static void add2slist(RAY  *r, int  *sl);


static int
inslist(                /* return index of source n if it's in list sl */
        int  *sl,
        int  n
)
{
        int  i;

        for (i = sl[0]; i > 0; i--)
                if (sl[i] == n)
                        return(i);
        return(0);
}


static int
srcmatch(       /* check for an id match on a light source */
        SRCREC  *sp,
        char  *id
)
{
        char  *cp;
                                                /* check for relay sources */
        while ((cp = strchr(id, RELAYDELIM)) != NULL) {
                if (!(sp->sflags & SVIRTUAL) || sp->so == NULL)
                        return(0);
                if (strncmp(id, sp->so->oname, cp-id) || sp->so->oname[cp-id])
                        return(0);
                id = cp + 1;                            /* relay to next */
                sp = source + sp->sa.sv.sn;
        }
        if (sp->sflags & SVIRTUAL || sp->so == NULL)
                return(0);
        return(!strcmp(id, sp->so->oname));
}


static void
add2slist(      /* add source list to ray's */
        RAY  *r,
        int  *sl
)
{
        static int  slspare[MAXSLIST+1];        /* in case of emergence */
        int  i;

        if (sl == NULL || sl[0] == 0)           /* nothing to add */
                return;
        if (r->slights == NULL)
                (r->slights = slspare)[0] = 0;  /* just once per ray path */
        for (i = sl[0]; i > 0; i--)
                if (!inslist(r->slights, sl[i])) {
                        if (r->slights[0] >= MAXSLIST)
                                error(INTERNAL,
                                        "scattering source list overflow");
                        r->slights[++r->slights[0]] = sl[i];
                }
}


int
m_mist(         /* process a ray entering or leaving some mist */
        OBJREC  *m,
        RAY  *r
)
{
        RAY  p;
        int  *myslist = NULL;
        int  newslist[MAXSLIST+1];
        COLOR  mext;
        double  re, ge, be;
        int  i, j;
                                        /* check arguments */
        if (m->oargs.nfargs > 7)
                objerror(m, USER, "bad arguments");
                                        /* get source indices */
        if (m->oargs.nsargs > 0 && (myslist = (int *)m->os) == NULL) {
                if (m->oargs.nsargs > MAXSLIST)
                        objerror(m, INTERNAL, "too many sources in list");
                myslist = (int *)malloc((m->oargs.nsargs+1)*sizeof(int));
                if (myslist == NULL)
                        goto memerr;
                myslist[0] = 0;                 /* size is first in list */
                for (j = 0; j < m->oargs.nsargs; j++) {
                        i = nsources;           /* look up each source id */
                        while (i--)
                                if (srcmatch(source+i, m->oargs.sarg[j]))
                                        break;
                        if (i < 0) {
                                sprintf(errmsg, "unknown source \"%s\"",
                                                m->oargs.sarg[j]);
                                objerror(m, WARNING, errmsg);
                        } else if (inslist(myslist, i)) {
                                sprintf(errmsg, "duplicate source \"%s\"",
                                                m->oargs.sarg[j]);
                                objerror(m, WARNING, errmsg);
                        } else
                                myslist[++myslist[0]] = i;
                }
                m->os = (char *)myslist;
        }
        if (m->oargs.nfargs > 2) {              /* compute extinction */
                setcolor(mext, m->oargs.farg[0], m->oargs.farg[1],
                                m->oargs.farg[2]);
                raytexture(r, m->omod);                 /* get modifiers */
                multscolor(mext, r->pcol);
        } else
                setcolor(mext, 0., 0., 0.);
                                                /* start transmitted ray */
        if (rayorigin(&p, TRANS, r, NULL) < 0)
                return(1);
        VCOPY(p.rdir, r->rdir);
        p.slights = newslist;
        if (r->slights != NULL)                 /* copy old list if one */
                for (j = r->slights[0]; j >= 0; j--)
                        p.slights[j] = r->slights[j];
        else
                p.slights[0] = 0;
        if (r->rod > 0.) {                      /* entering ray */
                addcolor(p.cext, mext);
                if (m->oargs.nfargs > 5)
                        setcolor(p.albedo, m->oargs.farg[3],
                                        m->oargs.farg[4], m->oargs.farg[5]);
                if (m->oargs.nfargs > 6)
                        p.gecc = m->oargs.farg[6];
                add2slist(&p, myslist);                 /* add to list */
        } else {                                /* leaving ray */
                if (myslist != NULL) {                  /* delete from list */
                        for (j = myslist[0]; j > 0; j--)
                                if ( (i = inslist(p.slights, myslist[j])) )
                                        p.slights[i] = -1;
                        for (i = 0, j = 1; j <= p.slights[0]; j++)
                                if (p.slights[j] != -1)
                                        p.slights[++i] = p.slights[j];
                        if (p.slights[0] - i < myslist[0]) {    /* fix old */
                                addcolor(r->cext, mext);
                                if (m->oargs.nfargs > 5)
                                        setcolor(r->albedo, m->oargs.farg[3],
                                        m->oargs.farg[4], m->oargs.farg[5]);
                                if (m->oargs.nfargs > 6)
                                        r->gecc = m->oargs.farg[6];
                                add2slist(r, myslist);
                        }
                        p.slights[0] = i;
                }
                if ((re = colval(r->cext,RED) - colval(mext,RED)) <
                                colval(cextinction,RED))
                        re = colval(cextinction,RED);
                if ((ge = colval(r->cext,GRN) - colval(mext,GRN)) <
                                colval(cextinction,GRN))
                        ge = colval(cextinction,GRN);
                if ((be = colval(r->cext,BLU) - colval(mext,BLU)) <
                                colval(cextinction,BLU))
                        be = colval(cextinction,BLU);
                setcolor(p.cext, re, ge, be);
                if (m->oargs.nfargs > 5)
                        copycolor(p.albedo, salbedo);
                if (m->oargs.nfargs > 6)
                        p.gecc = seccg;
        }
        rayvalue(&p);                           /* calls rayparticipate() */
        copyscolor(r->rcol, p.rcol);            /* return value */
        copyscolor(r->mcol, p.mcol);
        r->rmt = r->rot + p.rmt;
        r->rxt = r->rot + p.rxt;
        return(1);
memerr:
        error(SYSTEM, "out of memory in m_mist");
        return 0; /* pro forma return */
}
Revision:	2.21
Committed:	Wed Nov 15 18:02:53 2023 UTC (23 months, 3 weeks ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad6R0, HEAD
Changes since 2.20:	+4 -4 lines
Log Message:	feat(rpict,rtrace,rcontrib,rtpict): Hyperspectral rendering (except photon map)
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.21	static const char RCSid[] = "$Id: m_mist.c,v 2.20 2019/02/13 02:38:26 greg Exp $";
3	greg	2.1	#endif
4			/*
5			* Mist volumetric material.
6			*/
7
8	greg	2.11	#include "copyright.h"
9	greg	2.10
10	schorsch	2.13	#include <string.h>
11
12	greg	2.1	#include "ray.h"
13			#include "source.h"
14	schorsch	2.15	#include "rtotypes.h"
15	greg	2.1
16			/*
17			* A mist volume is used to specify a region in the scene where a certain
18			* light source (or sources) is going to contribute to scattering. The
19			* material can add to the existing global medium, and override any ray
20			* settings for scattering albedo and eccentricity. Overlapping mist
21			* regions should agree w.r.t. albedo and eccentricity, and
22			* should have disjoint source lists.
23			*
24			* A pattern, if used, should compute the line integral of extinction,
25			* and will modify the first three arguments directly. This will tend
26			* to invalidate results when there are other objects intersected within
27			* the mist region.
28			*
29			* The string arguments for MAT_MIST are the identifiers for the important
30			* light sources, which will be looked up in the source array. The last
31			* source found matching a name is the one used. A relayed light source
32			* may be indicated by the relay surface name, followed by a '>' character,
33			* followed by the relayed source name (which may be another relay).
34			*
35			* Up to five real arguments may be given for MAT_MIST:
36			*
37	greg	2.6	* [ext_r ext_g ext_b [albedo_r albedo_g albedo_b [gecc]]]
38	greg	2.1	*
39			* The primaries indicate medium extinction per unit length (absorption
40	greg	2.5	* plus scattering), which is added to the global extinction coefficient, set
41			* by the -me option. The albedo is the ratio of scattering to extinction,
42	greg	2.1	* and is set globally by the -ma option (salbedo) and overridden here.
43			* The Heyney-Greenstein eccentricity parameter (-mg seccg) indicates how much
44			* scattering favors the forward direction. A value of 0 means isotropic
45			* scattering. A value approaching 1 indicates strong forward scattering.
46			*/
47
48	greg	2.7	#ifndef MAXSLIST
49			#define MAXSLIST 32 /* maximum sources to check */
50			#endif
51
52	greg	2.1	#define RELAYDELIM '>' /* relay delimiter character */
53
54	schorsch	2.15	static int inslist(int *sl, int n);
55			static int srcmatch(SRCREC sp, char id);
56			static void add2slist(RAY r, int sl);
57
58	greg	2.1
59			static int
60	schorsch	2.15	inslist( /* return index of source n if it's in list sl */
61	greg	2.18	int *sl,
62			int n
63	schorsch	2.15	)
64	greg	2.1	{
65	greg	2.18	int i;
66	greg	2.1
67			for (i = sl[0]; i > 0; i--)
68			if (sl[i] == n)
69			return(i);
70			return(0);
71			}
72
73
74			static int
75	schorsch	2.15	srcmatch( /* check for an id match on a light source */
76	greg	2.18	SRCREC *sp,
77			char *id
78	schorsch	2.15	)
79	greg	2.1	{
80	greg	2.18	char *cp;
81	greg	2.2	/* check for relay sources */
82	schorsch	2.13	while ((cp = strchr(id, RELAYDELIM)) != NULL) {
83	greg	2.2	if (!(sp->sflags & SVIRTUAL) \|\| sp->so == NULL)
84	greg	2.1	return(0);
85	greg	2.2	if (strncmp(id, sp->so->oname, cp-id) \|\| sp->so->oname[cp-id])
86	greg	2.1	return(0);
87	greg	2.2	id = cp + 1; /* relay to next */
88			sp = source + sp->sa.sv.sn;
89	greg	2.1	}
90	greg	2.2	if (sp->sflags & SVIRTUAL \|\| sp->so == NULL)
91	greg	2.1	return(0);
92	greg	2.2	return(!strcmp(id, sp->so->oname));
93	greg	2.1	}
94
95
96	greg	2.10	static void
97	schorsch	2.15	add2slist( /* add source list to ray's */
98	greg	2.18	RAY *r,
99			int *sl
100	schorsch	2.15	)
101	greg	2.2	{
102			static int slspare[MAXSLIST+1]; /* in case of emergence */
103	greg	2.18	int i;
104	greg	2.2
105			if (sl == NULL \|\| sl[0] == 0) /* nothing to add */
106			return;
107			if (r->slights == NULL)
108			(r->slights = slspare)[0] = 0; /* just once per ray path */
109			for (i = sl[0]; i > 0; i--)
110			if (!inslist(r->slights, sl[i])) {
111			if (r->slights[0] >= MAXSLIST)
112	gregl	2.9	error(INTERNAL,
113			"scattering source list overflow");
114	greg	2.2	r->slights[++r->slights[0]] = sl[i];
115			}
116			}
117
118
119	greg	2.18	int
120	schorsch	2.15	m_mist( /* process a ray entering or leaving some mist */
121			OBJREC *m,
122	greg	2.18	RAY *r
123	schorsch	2.15	)
124	greg	2.1	{
125			RAY p;
126			int *myslist = NULL;
127			int newslist[MAXSLIST+1];
128			COLOR mext;
129			double re, ge, be;
130	greg	2.18	int i, j;
131	greg	2.1	/* check arguments */
132	greg	2.8	if (m->oargs.nfargs > 7)
133	greg	2.1	objerror(m, USER, "bad arguments");
134			/* get source indices */
135	greg	2.4	if (m->oargs.nsargs > 0 && (myslist = (int *)m->os) == NULL) {
136	greg	2.2	if (m->oargs.nsargs > MAXSLIST)
137	gregl	2.9	objerror(m, INTERNAL, "too many sources in list");
138	greg	2.1	myslist = (int )malloc((m->oargs.nsargs+1)sizeof(int));
139			if (myslist == NULL)
140			goto memerr;
141	greg	2.2	myslist[0] = 0; /* size is first in list */
142			for (j = 0; j < m->oargs.nsargs; j++) {
143	greg	2.1	i = nsources; /* look up each source id */
144			while (i--)
145	greg	2.2	if (srcmatch(source+i, m->oargs.sarg[j]))
146	greg	2.1	break;
147			if (i < 0) {
148			sprintf(errmsg, "unknown source \"%s\"",
149	greg	2.2	m->oargs.sarg[j]);
150	greg	2.1	objerror(m, WARNING, errmsg);
151	greg	2.2	} else if (inslist(myslist, i)) {
152			sprintf(errmsg, "duplicate source \"%s\"",
153			m->oargs.sarg[j]);
154			objerror(m, WARNING, errmsg);
155	greg	2.1	} else
156	greg	2.2	myslist[++myslist[0]] = i;
157	greg	2.1	}
158			m->os = (char *)myslist;
159			}
160			if (m->oargs.nfargs > 2) { /* compute extinction */
161			setcolor(mext, m->oargs.farg[0], m->oargs.farg[1],
162			m->oargs.farg[2]);
163			raytexture(r, m->omod); /* get modifiers */
164	greg	2.21	multscolor(mext, r->pcol);
165	greg	2.1	} else
166			setcolor(mext, 0., 0., 0.);
167			/* start transmitted ray */
168	greg	2.17	if (rayorigin(&p, TRANS, r, NULL) < 0)
169	greg	2.1	return(1);
170			VCOPY(p.rdir, r->rdir);
171			p.slights = newslist;
172	greg	2.2	if (r->slights != NULL) /* copy old list if one */
173	greg	2.1	for (j = r->slights[0]; j >= 0; j--)
174			p.slights[j] = r->slights[j];
175			else
176			p.slights[0] = 0;
177			if (r->rod > 0.) { /* entering ray */
178			addcolor(p.cext, mext);
179	greg	2.6	if (m->oargs.nfargs > 5)
180			setcolor(p.albedo, m->oargs.farg[3],
181			m->oargs.farg[4], m->oargs.farg[5]);
182			if (m->oargs.nfargs > 6)
183			p.gecc = m->oargs.farg[6];
184	greg	2.2	add2slist(&p, myslist); /* add to list */
185			} else { /* leaving ray */
186			if (myslist != NULL) { /* delete from list */
187	greg	2.1	for (j = myslist[0]; j > 0; j--)
188	schorsch	2.14	if ( (i = inslist(p.slights, myslist[j])) )
189	greg	2.2	p.slights[i] = -1;
190			for (i = 0, j = 1; j <= p.slights[0]; j++)
191			if (p.slights[j] != -1)
192			p.slights[++i] = p.slights[j];
193			if (p.slights[0] - i < myslist[0]) { /* fix old */
194			addcolor(r->cext, mext);
195	greg	2.6	if (m->oargs.nfargs > 5)
196			setcolor(r->albedo, m->oargs.farg[3],
197			m->oargs.farg[4], m->oargs.farg[5]);
198			if (m->oargs.nfargs > 6)
199			r->gecc = m->oargs.farg[6];
200	greg	2.2	add2slist(r, myslist);
201			}
202			p.slights[0] = i;
203			}
204	greg	2.5	if ((re = colval(r->cext,RED) - colval(mext,RED)) <
205			colval(cextinction,RED))
206			re = colval(cextinction,RED);
207			if ((ge = colval(r->cext,GRN) - colval(mext,GRN)) <
208			colval(cextinction,GRN))
209			ge = colval(cextinction,GRN);
210			if ((be = colval(r->cext,BLU) - colval(mext,BLU)) <
211			colval(cextinction,BLU))
212			be = colval(cextinction,BLU);
213			setcolor(p.cext, re, ge, be);
214	greg	2.6	if (m->oargs.nfargs > 5)
215			copycolor(p.albedo, salbedo);
216			if (m->oargs.nfargs > 6)
217	greg	2.1	p.gecc = seccg;
218			}
219			rayvalue(&p); /* calls rayparticipate() */
220	greg	2.21	copyscolor(r->rcol, p.rcol); /* return value */
221			copyscolor(r->mcol, p.mcol);
222	greg	2.19	r->rmt = r->rot + p.rmt;
223			r->rxt = r->rot + p.rxt;
224	greg	2.1	return(1);
225			memerr:
226			error(SYSTEM, "out of memory in m_mist");
227	schorsch	2.15	return 0; /* pro forma return */
228	greg	2.1	}