--- ray/src/common/fvect.c	2013/04/03 00:22:12	2.18
+++ ray/src/common/fvect.c	2014/12/08 23:51:12	2.21
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: fvect.c,v 2.18 2013/04/03 00:22:12 greg Exp $";
+static const char	RCSid[] = "$Id: fvect.c,v 2.21 2014/12/08 23:51:12 greg Exp $";
 #endif
 /*
  *  fvect.c - routines for floating-point vector calculations
@@ -7,11 +7,32 @@ static const char	RCSid[] = "$Id: fvect.c,v 2.18 2013/
 
 #include "copyright.h"
 
+#define _USE_MATH_DEFINES
 #include  <math.h>
 #include  "fvect.h"
+#include  "random.h"
 
+double
+Acos(double x)			/* insurance for touchy math library */
+{
+	if (x <= -1.+FTINY*FTINY)
+		return(M_PI);
+	if (x >= 1.-FTINY*FTINY)
+		return(.0);
+	return(acos(x));
+}
 
 double
+Asin(double x)			/* insurance for touchy math library */
+{
+	if (x <= -1.+FTINY*FTINY)
+		return(-M_PI/2.);
+	if (x >= 1.-FTINY*FTINY)
+		return(M_PI/2);
+	return(asin(x));
+}
+
+double
 fdot(				/* return the dot product of two vectors */
 const FVECT v1,
 const FVECT v2
@@ -85,6 +106,12 @@ const FVECT v1,
 const FVECT v2
 )
 {
+	if ((vres == v1) | (vres == v2)) {
+		FVECT	vtmp;
+		VCROSS(vtmp, v1, v2);
+		VCOPY(vres, vtmp);
+		return;
+	}
 	VCROSS(vres, v1, v2);
 }
 
@@ -125,6 +152,29 @@ FVECT  v
 	v[2] *= d;
 
 	return(len);
+}
+
+
+int
+getperpendicular(		/* choose random perpedicular direction */
+FVECT vp,				/* returns normalized */
+const FVECT v				/* input vector must be normalized */
+)
+{
+	FVECT	v1;
+	int	i;
+					/* randomize other coordinates */
+	v1[0] = 0.5 - frandom();
+	v1[1] = 0.5 - frandom();
+	v1[2] = 0.5 - frandom();
+	for (i = 3; i--; )
+		if ((-0.6 < v[i]) & (v[i] < 0.6))
+			break;
+	if (i < 0)
+		return(0);
+	v1[i] = 1.0;
+	fcross(vp, v1, v);
+	return(normalize(vp) > 0.0);
 }