--- ray/src/util/genBSDF.pl	2019/06/10 13:58:49	2.83
+++ ray/src/util/genBSDF.pl	2021/12/12 20:32:21	2.87
@@ -1,5 +1,5 @@
 #!/usr/bin/perl -w
-# RCSid $Id: genBSDF.pl,v 2.83 2019/06/10 13:58:49 greg Exp $
+# RCSid $Id: genBSDF.pl,v 2.87 2021/12/12 20:32:21 greg Exp $
 #
 # Compute BSDF based on geometry and material description
 #
@@ -324,8 +324,9 @@ sub do_ttree_dir {
 				qq{-e "r2=rand(-5.37138*recno+67.1737811)" } .
 				qq{-e "r3=rand(+3.17603772*recno+83.766771)" } .
 				qq{-e "r4=rand(-1.5839226*recno-59.82712)" } .
-				qq{-e "Dx=1-2*(\$1+r1)/$ns" } .
-				qq{-e "Dy=min(1/$ns,sqrt(1-Dx*Dx))*(2*r2-1)" } .
+				qq{-e "odds(n):if(.5*n-floor(.5*n)-.25,-1,1)"} .
+				qq{-e "Dx=1-(\$1+r1)/$ns2" } .
+				qq{-e "Dy=min(1/$ns,sqrt(1-Dx*Dx))*odds(\$1)*r2" } .
 				qq{-e "Dz=sqrt(1-Dx*Dx-Dy*Dy)" } .
 				qq{-e "xp=(\$3+r2)*(($dim[1]-$dim[0])/$nx)+$dim[0]" } .
 				qq{-e "yp=(\$2+r3)*(($dim[3]-$dim[2])/$ny)+$dim[2]" } .
@@ -339,8 +340,9 @@ sub do_ttree_dir {
 				qq{-e 'r2=rand(-5.37138*recno+67.1737811)' } .
 				qq{-e 'r3=rand(+3.17603772*recno+83.766771)' } .
 				qq{-e 'r4=rand(-1.5839226*recno-59.82712)' } .
-				qq{-e 'Dx=1-2*(\$1+r1)/$ns' } .
-				qq{-e 'Dy=min(1/$ns,sqrt(1-Dx*Dx))*(2*r2-1)' } .
+				qq{-e 'odds(n):if(.5*n-floor(.5*n)-.25,-1,1)' } .
+				qq{-e 'Dx=1-(\$1+r1)/$ns2' } .
+				qq{-e 'Dy=min(1/$ns,sqrt(1-Dx*Dx))*odds(\$1)*r2' } .
 				qq{-e 'Dz=sqrt(1-Dx*Dx-Dy*Dy)' } .
 				qq{-e 'xp=(\$3+r3)*(($dim[1]-$dim[0])/$nx)+$dim[0]' } .
 				qq{-e 'yp=(\$2+r4)*(($dim[3]-$dim[2])/$ny)+$dim[2]' } .
@@ -434,7 +436,7 @@ sub ttree_comp {
 		}
 	}
 	if ($pctcull >= 0) {
-		my $avg = ( $dorecip && "$typ" =~ /^r[fb]/ ) ? " -a" : "";
+		my $avg = ( $dorecip && ( $ttree == 3 || "$typ" =~ /^r[fb]/ ) ) ? " -a" : "";
 		my $pcull = ("$spec" eq "Visible") ? $pctcull :
 						     (100 - (100-$pctcull)*.25) ;
 		if ($windoz) {