src/rt/m_mirror.c

#ifndef lint
static const char       RCSid[] = "$Id: m_mirror.c,v 2.24 2025/05/29 16:42:28 greg Exp $";
#endif
/*
 * Routines for mirror material supporting virtual light sources
 */

#include "copyright.h"

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

/*
 * The real arguments for MAT_MIRROR are simply:
 *
 *      3 rrefl grefl brefl
 *
 * Additionally, the user may specify a single string argument
 * which is interpreted as the name of the material to use
 * instead of the mirror if the ray being considered is not
 * part of the direct calculation.
 */

static int mir_proj(MAT4  pm, OBJREC  *o, SRCREC  *s, int  n);
static void mirrorproj(MAT4  m, FVECT  nv, double  offs);

VSMATERIAL  mirror_vs = {mir_proj, 1};


int
m_mirror(                       /* shade mirrored ray */
        OBJREC  *m,
        RAY  *r
)
{
                                        /* check arguments */
        if (m->oargs.nfargs != 3 || m->oargs.nsargs > 1)
                objerror(m, USER, "bad number of arguments");
                                        /* check for substitute material */
                                        /* but avoid double-counting */
        if (m->oargs.nsargs > 0 &&
                        (r->rsrc < 0 || source[r->rsrc].so != r->ro)) {
                int     passOK = (r->rod < 0.) |
                                        !(r->crtype & (AMBIENT|SPECULAR));
                if (strcmp(m->oargs.sarg[0], VOIDID)) {
                        OBJECT  altmod = lastmod(objndx(m), m->oargs.sarg[0]);
                        OBJREC  *altmat;
                        if (passOK)             /* no double-count hazard? */
                                return(rayshade(r, altmod));
                        if (altmod == OVOID ||  /* else check alternate type */
                                        (altmat = findmaterial(objptr(altmod))) == NULL)
                                return(0);
                        if (istransp(altmat))   /* pass "transparent" materials */
                                return(rayshade(r, altmod));
                } else if (passOK) {
                        raytrans(r);            /* "safe" void passage */
                        return(1);
                }
        }
                                        /* check for bad source ray */
        if (r->rsrc >= 0 && source[r->rsrc].so != r->ro)
                return(1);

        if (r->rod < 0.) {              /* back is black */
                if (!backvis)
                        raytrans(r);    /* unless back visibility is off */
                return(1);
        }
        {                               /* new context for stack memory */
        SCOLOR  mcolor;
        RAY  nr;
        int  rpure = 1;
        int  i;
                                        /* get modifiers */
        raytexture(r, m->omod);
                                        /* assign material color */
        setscolor(mcolor, m->oargs.farg[0],
                        m->oargs.farg[1],
                        m->oargs.farg[2]);
        smultscolor(mcolor, r->pcol);
                                        /* compute reflected ray */
        if (r->rsrc >= 0) {                     /* relayed light source */
                rayorigin(&nr, REFLECTED, r, mcolor);
                                        /* ignore textures */
                for (i = 0; i < 3; i++)
                        nr.rdir[i] = r->rdir[i] + 2.*r->rod*r->ron[i];
                                        /* source we're aiming for next */
                nr.rsrc = source[r->rsrc].sa.sv.sn;
        } else {                                /* ordinary reflection */
                FVECT  pnorm;
                double  pdot;

                if (rayorigin(&nr, REFLECTED, r, mcolor) < 0)
                        return(1);
                if (!(r->crtype & AMBIENT) &&
                                DOT(r->pert,r->pert) > FTINY*FTINY) {
                        pdot = raynormal(pnorm, r);     /* use textures */
                        for (i = 0; i < 3; i++)
                                nr.rdir[i] = r->rdir[i] + 2.*pdot*pnorm[i];
                        rpure = 0;
                }
                                                /* check for penetration */
                if (rpure || DOT(nr.rdir, r->ron) <= FTINY)
                        for (i = 0; i < 3; i++)
                                nr.rdir[i] = r->rdir[i] + 2.*r->rod*r->ron[i];
        }
        checknorm(nr.rdir);
        rayvalue(&nr);
        smultscolor(nr.rcol, nr.rcoef);
        copyscolor(r->mcol, nr.rcol);
        saddscolor(r->rcol, nr.rcol);
        r->rmt = r->rot;
        if (rpure && r->ro != NULL && isflat(r->ro->otype))
                r->rmt += raydistance(&nr);
        }                               /* end stack context */
        return(1);
}


static int
mir_proj(               /* compute a mirror's projection */
        MAT4  pm,
        OBJREC  *o,
        SRCREC  *s,
        int  n
)
{
        double  corr = 1.;
        FVECT  nv, sc;
        double  od, offs;
        int  i;
                                /* get surface normal and offset */
        offs = od = getplaneq(nv, o);
        if (s->sflags & SDISTANT)
                offs = 0.;
                                /* check for extreme point behind */
        if (s->sflags & SCIR) {
                if (s->sflags & (SFLAT|SDISTANT))
                        corr = 1.12837917;      /* correct setflatss() */
                else
                        corr = 1.0/0.7236;      /* correct sphsetsrc() */
        }
        VCOPY(sc, s->sloc);
        for (i = s->sflags & SFLAT ? SV : SW; i >= 0; i--)
                if (DOT(nv, s->ss[i]) > offs)
                        VSUM(sc, sc, s->ss[i], corr);
                else
                        VSUM(sc, sc, s->ss[i], -corr);
        if (DOT(sc, nv) <= offs+FTINY)
                return(0);
                                /* everything OK -- compute projection */
        mirrorproj(pm, nv, od);
        return(1);
}


static void
mirrorproj(             /* get mirror projection for surface */
        MAT4  m,
        FVECT  nv,
        double  offs
)
{
        int  i, j;
                                        /* assign matrix */
        setident4(m);
        for (j = 0; j < 3; j++) {
                for (i = 0; i < 3; i++)
                        m[i][j] -= 2.*nv[i]*nv[j];
                m[3][j] = 2.*offs*nv[j];
        }
}
Revision:	2.25
Committed:	Sat May 31 00:52:54 2025 UTC (5 days, 6 hours ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	HEAD
Changes since 2.24:	+7 -5 lines
Log Message:	perf: Minor optimization to avoid putting unneeded RAY struct on stack
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.25	static const char RCSid[] = "$Id: m_mirror.c,v 2.24 2025/05/29 16:42:28 greg Exp $";
3	greg	1.1	#endif
4			/*
5			* Routines for mirror material supporting virtual light sources
6			*/
7
8	greg	2.9	#include "copyright.h"
9	greg	2.8
10	greg	1.1	#include "ray.h"
11			#include "otypes.h"
12	greg	2.24	#include "otspecial.h"
13	schorsch	2.10	#include "rtotypes.h"
14	greg	1.1	#include "source.h"
15
16			/*
17			* The real arguments for MAT_MIRROR are simply:
18			*
19			* 3 rrefl grefl brefl
20			*
21			* Additionally, the user may specify a single string argument
22			* which is interpreted as the name of the material to use
23			* instead of the mirror if the ray being considered is not
24			* part of the direct calculation.
25			*/
26
27	schorsch	2.10	static int mir_proj(MAT4 pm, OBJREC o, SRCREC s, int n);
28			static void mirrorproj(MAT4 m, FVECT nv, double offs);
29	greg	2.8
30	greg	1.1	VSMATERIAL mirror_vs = {mir_proj, 1};
31
32
33	greg	2.16	int
34	schorsch	2.10	m_mirror( /* shade mirrored ray */
35	greg	2.16	OBJREC *m,
36			RAY *r
37	schorsch	2.10	)
38	greg	1.1	{
39			/* check arguments */
40			if (m->oargs.nfargs != 3 \|\| m->oargs.nsargs > 1)
41			objerror(m, USER, "bad number of arguments");
42	greg	1.3	/* check for substitute material */
43	greg	2.14	/* but avoid double-counting */
44	greg	2.24	if (m->oargs.nsargs > 0 &&
45			(r->rsrc < 0 \|\| source[r->rsrc].so != r->ro)) {
46			int passOK = (r->rod < 0.) \|
47			!(r->crtype & (AMBIENT\|SPECULAR));
48			if (strcmp(m->oargs.sarg[0], VOIDID)) {
49			OBJECT altmod = lastmod(objndx(m), m->oargs.sarg[0]);
50			OBJREC *altmat;
51			if (passOK) /* no double-count hazard? */
52			return(rayshade(r, altmod));
53			if (altmod == OVOID \|\| /* else check alternate type */
54			(altmat = findmaterial(objptr(altmod))) == NULL)
55			return(0);
56			if (istransp(altmat)) /* pass "transparent" materials */
57			return(rayshade(r, altmod));
58			} else if (passOK) {
59			raytrans(r); /* "safe" void passage */
60	greg	2.4	return(1);
61			}
62	greg	1.1	}
63	greg	1.3	/* check for bad source ray */
64			if (r->rsrc >= 0 && source[r->rsrc].so != r->ro)
65	greg	2.3	return(1);
66	greg	1.3
67	greg	2.15	if (r->rod < 0.) { /* back is black */
68			if (!backvis)
69			raytrans(r); /* unless back visibility is off */
70	greg	2.3	return(1);
71	greg	2.15	}
72	greg	2.25	{ /* new context for stack memory */
73			SCOLOR mcolor;
74			RAY nr;
75			int rpure = 1;
76			int i;
77	greg	1.1	/* get modifiers */
78			raytexture(r, m->omod);
79			/* assign material color */
80	greg	2.23	setscolor(mcolor, m->oargs.farg[0],
81	greg	1.1	m->oargs.farg[1],
82			m->oargs.farg[2]);
83	greg	2.23	smultscolor(mcolor, r->pcol);
84	greg	1.1	/* compute reflected ray */
85			if (r->rsrc >= 0) { /* relayed light source */
86	greg	2.11	rayorigin(&nr, REFLECTED, r, mcolor);
87	greg	1.1	/* ignore textures */
88			for (i = 0; i < 3; i++)
89			nr.rdir[i] = r->rdir[i] + 2.r->rodr->ron[i];
90			/* source we're aiming for next */
91	greg	1.2	nr.rsrc = source[r->rsrc].sa.sv.sn;
92	greg	1.1	} else { /* ordinary reflection */
93			FVECT pnorm;
94			double pdot;
95
96	greg	2.11	if (rayorigin(&nr, REFLECTED, r, mcolor) < 0)
97	greg	2.3	return(1);
98	greg	2.16	if (!(r->crtype & AMBIENT) &&
99			DOT(r->pert,r->pert) > FTINY*FTINY) {
100	greg	2.6	pdot = raynormal(pnorm, r); /* use textures */
101			for (i = 0; i < 3; i++)
102			nr.rdir[i] = r->rdir[i] + 2.pdotpnorm[i];
103			rpure = 0;
104			}
105	greg	2.2	/* check for penetration */
106	greg	2.6	if (rpure \|\| DOT(nr.rdir, r->ron) <= FTINY)
107	greg	2.2	for (i = 0; i < 3; i++)
108			nr.rdir[i] = r->rdir[i] + 2.r->rodr->ron[i];
109	greg	1.1	}
110	greg	2.13	checknorm(nr.rdir);
111	greg	1.1	rayvalue(&nr);
112	greg	2.23	smultscolor(nr.rcol, nr.rcoef);
113			copyscolor(r->mcol, nr.rcol);
114			saddscolor(r->rcol, nr.rcol);
115	greg	2.21	r->rmt = r->rot;
116	greg	2.6	if (rpure && r->ro != NULL && isflat(r->ro->otype))
117	greg	2.22	r->rmt += raydistance(&nr);
118	greg	2.25	} /* end stack context */
119	greg	2.3	return(1);
120	greg	1.1	}
121
122
123	greg	2.8	static int
124	schorsch	2.10	mir_proj( /* compute a mirror's projection */
125			MAT4 pm,
126	greg	2.16	OBJREC *o,
127	schorsch	2.10	SRCREC *s,
128			int n
129			)
130	greg	1.1	{
131	greg	2.12	double corr = 1.;
132	greg	2.5	FVECT nv, sc;
133	greg	2.12	double od, offs;
134			int i;
135	greg	1.1	/* get surface normal and offset */
136	greg	2.12	offs = od = getplaneq(nv, o);
137			if (s->sflags & SDISTANT)
138			offs = 0.;
139			/* check for extreme point behind */
140			if (s->sflags & SCIR) {
141			if (s->sflags & (SFLAT\|SDISTANT))
142			corr = 1.12837917; /* correct setflatss() */
143			else
144			corr = 1.0/0.7236; /* correct sphsetsrc() */
145			}
146	greg	2.5	VCOPY(sc, s->sloc);
147			for (i = s->sflags & SFLAT ? SV : SW; i >= 0; i--)
148	greg	2.12	if (DOT(nv, s->ss[i]) > offs)
149			VSUM(sc, sc, s->ss[i], corr);
150	greg	2.5	else
151	greg	2.12	VSUM(sc, sc, s->ss[i], -corr);
152			if (DOT(sc, nv) <= offs+FTINY)
153	greg	1.1	return(0);
154			/* everything OK -- compute projection */
155			mirrorproj(pm, nv, od);
156			return(1);
157			}
158
159
160	schorsch	2.10	static void
161			mirrorproj( /* get mirror projection for surface */
162	greg	2.16	MAT4 m,
163	schorsch	2.10	FVECT nv,
164			double offs
165			)
166	greg	1.1	{
167	greg	2.16	int i, j;
168	greg	1.1	/* assign matrix */
169			setident4(m);
170	greg	1.2	for (j = 0; j < 3; j++) {
171			for (i = 0; i < 3; i++)
172	greg	1.1	m[i][j] -= 2.nv[i]nv[j];
173			m[3][j] = 2.offsnv[j];
174	greg	1.2	}
175	greg	1.1	}