--- ray/src/rt/m_mirror.c	2005/04/19 01:15:06	2.11
+++ ray/src/rt/m_mirror.c	2023/11/15 18:02:53	2.23
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: m_mirror.c,v 2.11 2005/04/19 01:15:06 greg Exp $";
+static const char	RCSid[] = "$Id: m_mirror.c,v 2.23 2023/11/15 18:02:53 greg Exp $";
 #endif
 /*
  * Routines for mirror material supporting virtual light sources
@@ -29,22 +29,24 @@ static void mirrorproj(MAT4  m, FVECT  nv, double  off
 VSMATERIAL  mirror_vs = {mir_proj, 1};
 
 
-extern int
+int
 m_mirror(			/* shade mirrored ray */
-	register OBJREC  *m,
-	register RAY  *r
+	OBJREC  *m,
+	RAY  *r
 )
 {
-	COLOR  mcolor;
+	SCOLOR  mcolor;
 	RAY  nr;
 	int  rpure = 1;
-	register int  i;
+	int  i;
 					/* check arguments */
 	if (m->oargs.nfargs != 3 || m->oargs.nsargs > 1)
 		objerror(m, USER, "bad number of arguments");
 					/* check for substitute material */
-	if (m->oargs.nsargs > 0 &&
-			(r->rsrc < 0 || source[r->rsrc].so != r->ro)) {
+					/* but avoid double-counting */
+	if ( m->oargs.nsargs > 0 &&
+			(r->rsrc < 0 || source[r->rsrc].so != r->ro) &&
+			!(r->crtype & (AMBIENT|SPECULAR) && r->rod > 0.) ) {
 		if (!strcmp(m->oargs.sarg[0], VOIDID)) {
 			raytrans(r);
 			return(1);
@@ -55,15 +57,18 @@ m_mirror(			/* shade mirrored ray */
 	if (r->rsrc >= 0 && source[r->rsrc].so != r->ro)
 		return(1);
 
-	if (r->rod < 0.)		/* back is black */
+	if (r->rod < 0.) {		/* back is black */
+		if (!backvis)
+			raytrans(r);	/* unless back visibility is off */
 		return(1);
+	}
 					/* get modifiers */
 	raytexture(r, m->omod);
 					/* assign material color */
-	setcolor(mcolor, m->oargs.farg[0],
+	setscolor(mcolor, m->oargs.farg[0],
 			m->oargs.farg[1],
 			m->oargs.farg[2]);
-	multcolor(mcolor, r->pcol);
+	smultscolor(mcolor, r->pcol);
 					/* compute reflected ray */
 	if (r->rsrc >= 0) {			/* relayed light source */
 		rayorigin(&nr, REFLECTED, r, mcolor);
@@ -78,7 +83,8 @@ m_mirror(			/* shade mirrored ray */
 
 		if (rayorigin(&nr, REFLECTED, r, mcolor) < 0)
 			return(1);
-		if (DOT(r->pert,r->pert) > FTINY*FTINY) {
+		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];
@@ -89,11 +95,14 @@ m_mirror(			/* shade mirrored ray */
 			for (i = 0; i < 3; i++)
 				nr.rdir[i] = r->rdir[i] + 2.*r->rod*r->ron[i];
 	}
+	checknorm(nr.rdir);
 	rayvalue(&nr);
-	multcolor(nr.rcol, nr.rcoef);
-	addcolor(r->rcol, nr.rcol);
+	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->rt = r->rot + nr.rt;
+		r->rmt += raydistance(&nr);
 	return(1);
 }
 
@@ -101,26 +110,33 @@ m_mirror(			/* shade mirrored ray */
 static int
 mir_proj(		/* compute a mirror's projection */
 	MAT4  pm,
-	register OBJREC  *o,
+	OBJREC  *o,
 	SRCREC  *s,
 	int  n
 )
 {
+	double	corr = 1.;
 	FVECT  nv, sc;
-	double  od;
-	register int  i, j;
+	double  od, offs;
+	int  i;
 				/* get surface normal and offset */
-	od = getplaneq(nv, o);
-				/* check for extreme point for behind */
+	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]) > 0.)
-			for (j = 0; j < 3; j++)
-				sc[j] += s->ss[i][j];
+		if (DOT(nv, s->ss[i]) > offs)
+			VSUM(sc, sc, s->ss[i], corr);
 		else
-			for (j = 0; j < 3; j++)
-				sc[j] -= s->ss[i][j];
-	if (DOT(sc, nv) <= (s->sflags & SDISTANT ? FTINY : od+FTINY))
+			VSUM(sc, sc, s->ss[i], -corr);
+	if (DOT(sc, nv) <= offs+FTINY)
 		return(0);
 				/* everything OK -- compute projection */
 	mirrorproj(pm, nv, od);
@@ -130,12 +146,12 @@ mir_proj(		/* compute a mirror's projection */
 
 static void
 mirrorproj(		/* get mirror projection for surface */
-	register MAT4  m,
+	MAT4  m,
 	FVECT  nv,
 	double  offs
 )
 {
-	register int  i, j;
+	int  i, j;
 					/* assign matrix */
 	setident4(m);
 	for (j = 0; j < 3; j++) {