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root/Development/ray/src/rt/glass.c

Comparing ray/src/rt/glass.c (file contents):
Revision 1.2 by greg, Wed Jun 7 08:38:33 1989 UTC vs.
Revision 2.4 by greg, Wed Oct 14 12:27:47 1992 UTC

#	Line 1 | Line 1
1	<	/* Copyright (c) 1986 Regents of the University of California */
1	>	/* Copyright (c) 1991 Regents of the University of California */
2
3		#ifndef lint
4		static char SCCSid[] = "$SunId$ LBL";
#	Line 32 | Line 32 | static char SCCSid[] = "$SunId$ LBL";
32		*      tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn
33		*
34		*  The transmission of standard 88% transmissivity glass is 0.96.
35	+	*  A refractive index other than the default can be used by giving
36	+	*  it as the fourth real argument.  The above formula no longer applies.
37	+	*
38		*  If we appear to hit the back side of the surface, then we
39		*  turn the normal around.
40		*/
#	Line 43 | Line 46 | m_glass(m, r)          /* color a ray which hit a thin glass s
46		OBJREC  *m;
47		register RAY  *r;
48		{
46	–	double  sqrt(), pow();
49		COLOR  mcolor;
50		double  pdot;
51		FVECT  pnorm;
52	<	double  cos2;
52	>	double  rindex, cos2;
53		COLOR  trans, refl;
54	<	double  d, r1;
54	>	double  d, r1e, r1m;
55	>	double  transtest, transdist;
56		RAY  p;
57		register int  i;
58	<
59	<	if (m->oargs.nfargs != 3)
58	>	/* check arguments */
59	>	if (m->oargs.nfargs == 3)
60	>	rindex = RINDEX;                /* default value of n */
61	>	else if (m->oargs.nfargs == 4)
62	>	rindex = m->oargs.farg[3];      /* use their value */
63	>	else
64		objerror(m, USER, "bad arguments");
65
66		setcolor(mcolor, m->oargs.farg[0], m->oargs.farg[1], m->oargs.farg[2]);
67
68		if (r->rod < 0.0)                       /* reorient if necessary */
69		flipsurface(r);
70	+	transtest = 0;
71		/* get modifiers */
72		raytexture(r, m->omod);
73		pdot = raynormal(pnorm, r);
74		/* angular transmission */
75	<	cos2 = sqrt( (1.0-1.0/RINDEX/RINDEX) +
76	<	pdot*pdot/(RINDEX*RINDEX) );
75	>	cos2 = sqrt( (1.0-1.0/(rindex*rindex)) +
76	>	pdot*pdot/(rindex*rindex) );
77		setcolor(mcolor, pow(colval(mcolor,RED), 1.0/cos2),
78		pow(colval(mcolor,GRN), 1.0/cos2),
79		pow(colval(mcolor,BLU), 1.0/cos2));
80
81		/* compute reflection */
82	<	r1 = (pdot - RINDEX*cos2) / (pdot + RINDEX*cos2);
83	<	d = (1.0/pdot - RINDEX/cos2) / (1.0/pdot + RINDEX/cos2);
84	<	r1 = (r1*r1 + d*d) / 2.0;
82	>	r1e = (pdot - rindex*cos2) / (pdot + rindex*cos2);
83	>	r1e *= r1e;
84	>	r1m = (1.0/pdot - rindex/cos2) / (1.0/pdot + rindex/cos2);
85	>	r1m *= r1m;
86		/* compute transmittance */
87		for (i = 0; i < 3; i++) {
88		d = colval(mcolor, i);
89	<	colval(trans,i) = (1.0-r1)*(1.0-r1)*d / (1.0 - r1*r1*d*d);
89	>	colval(trans,i) = .5*(1.0-r1e)*(1.0-r1e)*d/(1.0-r1e*r1e*d*d);
90	>	colval(trans,i) += .5*(1.0-r1m)*(1.0-r1m)*d/(1.0-r1m*r1m*d*d);
91		}
92		/* transmitted ray */
93		if (rayorigin(&p, r, TRANS, bright(trans)) == 0) {
94	<	VCOPY(p.rdir, r->rdir);
94	>	if (!(r->crtype & SHADOW) &&
95	>	DOT(r->pert,r->pert) > FTINY*FTINY) {
96	>	for (i = 0; i < 3; i++)         /* perturb direction */
97	>	p.rdir[i] = r->rdir[i] +
98	>	2.*(1.-rindex)*r->pert[i];
99	>	if (normalize(p.rdir) == 0.0) {
100	>	objerror(m, WARNING, "bad perturbation");
101	>	VCOPY(p.rdir, r->rdir);
102	>	}
103	>	} else {
104	>	VCOPY(p.rdir, r->rdir);
105	>	transtest = 2;
106	>	}
107		rayvalue(&p);
108		multcolor(p.rcol, r->pcol);     /* modify */
109		multcolor(p.rcol, trans);
110		addcolor(r->rcol, p.rcol);
111	+	transtest *= bright(p.rcol);
112	+	transdist = r->rot + p.rt;
113		}
114	+
115		if (r->crtype & SHADOW)                 /* skip reflected ray */
116		return;
117		/* compute reflectance */
118		for (i = 0; i < 3; i++) {
119		d = colval(mcolor, i);
120		d *= d;
121	<	colval(refl,i) = r1 * (1.0 + (1.0-2.0*r1)*d) / (1.0 - r1*r1*d);
121	>	colval(refl,i) = .5*r1e*(1.0+(1.0-2.0*r1e)*d)/(1.0-r1e*r1e*d);
122	>	colval(refl,i) += .5*r1m*(1.0+(1.0-2.0*r1m)*d)/(1.0-r1m*r1m*d);
123		}
124		/* reflected ray */
125		if (rayorigin(&p, r, REFLECTED, bright(refl)) == 0) {
#	Line 103 | Line 129 | register RAY  *r;
129		multcolor(p.rcol, refl);
130		addcolor(r->rcol, p.rcol);
131		}
132	+	if (transtest > bright(r->rcol))
133	+	r->rt = transdist;
134		}

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