diff -urN rt_v55/bubble.yaml rt_v56/bubble.yaml
--- rt_v55/bubble.yaml	1970-01-01 09:00:00.000000000 +0900
+++ rt_v56/bubble.yaml	2018-06-29 03:59:22.000000000 +0900
@@ -0,0 +1,10 @@
+all:
+- kind: or
+  args:
+  - kind: pipe
+  rtd: { base: 0.1, diff: 0.3, reflect: 0.5, reflact: 0.2, density: 1, reflect_backside: False }
+  m2g:
+  - ax.zoom_z(0.5)
+  - ax.slide_z(-0.5)
+  - ax.zoom_all(0.5)
+# EOF
diff -urN rt_v55/cross.c rt_v56/cross.c
--- rt_v55/cross.c	2018-06-15 21:57:23.000000000 +0900
+++ rt_v56/cross.c	2018-06-29 04:25:23.000000000 +0900
@@ -411,8 +411,11 @@
 		line_on_line_p( &r->l, r->t, r->p );
 		cross_get_nv( d->kind, &d->l2g, l_g, 0, r );
 		r->flags = 0;
+		if( prev_idx == r->idx ){
+			r->flags |= CROSS_FLAG_PREV;
+		}
 		area_ins( a, r->t, r, sizeof(*r) );
-		if(r->ang_nv_eyev > 0){
+		if(r->ang_nv_eyev >= 0){
 			area_not(a);
 		}
 	}else{ /* n == 2 */
diff -urN rt_v55/hair_line.yaml rt_v56/hair_line.yaml
--- rt_v55/hair_line.yaml	1970-01-01 09:00:00.000000000 +0900
+++ rt_v56/hair_line.yaml	2018-06-29 04:14:58.000000000 +0900
@@ -0,0 +1,9 @@
+all:
+- kind: or
+  args:
+  - kind: pipe
+    rtd: { base: 0.1, diff: 0.3, reflect: 0.5, reflact: 0.2, density: 2 }
+    m2g:
+    - ax.rot_y(90)
+    - ax.slide_y(2)
+# EOF