diff -urN wf-/data.c wf/data.c
--- wf-/data.c	2016-01-03 00:00:00.000000000 +0900
+++ wf/data.c	2016-01-03 02:00:00.000000000 +0900
@@ -20,6 +20,7 @@
 	CASE_RET(type_arc);
 	CASE_RET(type_arr);
 	CASE_RET(type_op_data_set);
+	CASE_RET(type_slice);
 	CASE_RET(type_slide);
 	CASE_RET(type_zoom);
 	CASE_RET(type_zoom_and_slide);
@@ -312,6 +313,14 @@
 }
 
 static void
+slice_draw(struct slice *sl, prm_t *prm)
+{
+	double sec = prm->sec;
+	int i = way_idx_rate(sl->ts, sl->n, &sec);
+	data_draw(&sl->ds[i], prm);
+}
+
+static void
 test_conv_draw(pos_t *p, prm_t *prm)
 {
 	if(!prm->skip_af){
@@ -358,6 +367,9 @@
 	case type_op_data_set:
 		op_data_set_draw(data->p, prm);
 		break;
+	case type_slice:
+		slice_draw(data->p, prm);
+		break;
 
 	case type_test_conv:
 		test_conv_draw(data->p, prm);
@@ -383,6 +395,14 @@
 }
 
 static void
+op_data_slice(struct slice *sl, data_t *data, prm_t *prm)
+{
+	double sec = prm->sec;
+	int i = way_idx_rate(sl->ts, sl->n, &sec);
+	op_data_draw(&sl->ds[i], data, prm);
+}
+
+static void
 op_data_slide(d3_t *slide, data_t *data, prm_t *prm)
 {
 	affin_t af;
@@ -575,6 +595,9 @@
 	case type_arr:
 		op_data_arr(op->p, data, prm);
 		break;
+	case type_slice:
+		op_data_slice(op->p, data, prm);
+		break;
 
 	case type_slide:
 		op_data_slide(op->p, data, prm);
diff -urN wf-/data.h wf/data.h
--- wf-/data.h	2016-01-03 00:00:00.000000000 +0900
+++ wf/data.h	2016-01-03 02:00:00.000000000 +0900
@@ -23,6 +23,7 @@
 
 #define type_arr			10
 #define type_op_data_set		11
+#define type_slice			12
 
 #define type_slide			100
 #define type_zoom			101
@@ -79,6 +80,12 @@
 	data_t *op, *data;
 };
 
+struct slice{
+	int n;
+	data_t *ds;
+	double *ts; /* way ts */
+};
+
 struct slide_way_liss{
 	pos_t ps, pe;
 	d3_t sec, init_sec;
diff -urN wf-/nt.c wf/nt.c
--- wf-/nt.c	2016-01-03 00:00:00.000000000 +0900
+++ wf/nt.c	2016-01-03 02:00:00.000000000 +0900
@@ -4,7 +4,7 @@
 fz(double sec, int ac, char **av)
 {
 	double r = 30;
-	double sky_deg = 10;
+	double sky_deg = 40;
 	pos_t p = {0,0,-r};
 	data_t data = { type_op_data_set, &(struct op_data_set){
 	  .op = &(data_t){ type_rot_way, &(struct rot_way){
@@ -31,7 +31,8 @@
 int
 main(int ac, char **av)
 {
-	double l_sec = 0, r_sec = 5, sec = 2.5;
+	double l_sec = 0, r_sec = 5, sec = (l_sec + r_sec) * 0.5;
+	double pipe_sec = 2;
 
 	while(r_sec - l_sec > 5*0.0000001){
 		sec = (l_sec + r_sec) * 0.5;
@@ -39,6 +40,6 @@
 		else l_sec = sec;
 	}
 	printf("sec=%f,5-sec=%f\n", sec, 5-sec);
-	printf("%f:%f=%f:5\n", sec, 5-sec, sec*5/(5-sec));
+	printf("%f:%f=%f:%f\n", sec, 5-sec, sec*pipe_sec/(5-sec), pipe_sec);
 	return 0;
 }
diff -urN wf-/way.c wf/way.c
--- wf-/way.c	2015-12-30 00:00:00.000000000 +0900
+++ wf/way.c	2016-01-03 02:00:00.000000000 +0900
@@ -8,8 +8,8 @@
 	return ts[ n-1 ] >= 0;
 }
 
-static int
-t_idx_rate(const double *ts, int n, double *t)
+int
+way_idx_rate(const double *ts, int n, double *t)
 {
 	/* t --> 0..1 , return idx */
 
@@ -48,7 +48,7 @@
 {
 	int n = way->n;
 	const double *ts = way->ts;
-	int idx = t_idx_rate(ts, n, &t);
+	int idx = way_idx_rate(ts, n, &t);
 	int nxt = (idx + 1) % n;
 
 	if(way->dg == 1){
diff -urN wf-/way.h wf/way.h
--- wf-/way.h	2016-01-03 00:00:00.000000000 +0900
+++ wf/way.h	2016-01-03 02:00:00.000000000 +0900
@@ -32,6 +32,7 @@
 #define WAY_V2(v1,v2,t1,t2,dg_)	{ .n=2, .vs=(double[]){v1,v2}, .ts=(double[]){t1,t2}, .ps=NULL, .dg=dg_ }
 
 
+int way_idx_rate(const double *ts, int n, double *t);
 void way_get(struct way *way, double t);
 
 
diff -urN wf-/wf_ex.c wf/wf_ex.c
--- wf-/wf_ex.c	2016-01-03 00:00:00.000000000 +0900
+++ wf/wf_ex.c	2016-01-03 02:00:00.000000000 +0900
@@ -309,6 +309,11 @@
 		}};
 
 		double r = 30;
+		double sky_deg = 40;
+		double sky_sec = 1.966005, pipe_sec = 2, half_sec = (sky_sec + pipe_sec) * 2;
+		data_t spin = { type_rot_way, &(struct rot_way){
+		  .l={D3_O,D3_I}, .deg_way=WAY_V2(0,360*4, sky_sec,sky_sec, 3) }};
+
 		data_t *half_pipe = &(data_t){ type_op_data_set, &(struct op_data_set){
 		  .op = &(data_t){ type_zoom_and_slide, (d3_t[]){{0.1,0.1,0.1},{-30,-30,-10}} },
 		  .data = &(data_t){ type_arr, (data_t[]){
@@ -321,6 +326,21 @@
 			{ type_copy_rot, &(struct copy_rot){ .n=5, .l=LINE_Y, .init_deg=-90+30, .step_deg=30 } },
 			{ type_end } }},
 		      .data = &(data_t){ type_cross, (pos_t[]){{-1,0,-r},{1,0,-r}} } }},
+		    { type_op_data_set, &(struct op_data_set){
+		      .op = &(data_t){ type_arr, (data_t[]){
+			{ type_copy_timeshift, &(struct copy_timeshift){
+			  .n=40, .init_sec=0, .step_sec=-1, .init=D3_O, .step=D3_O }},
+			{ type_rot_way, &(struct rot_way){
+			  .l=LINE_Z, .deg_way=WAY_V2(0,360, 60,0, 1) }},
+			{ type_slide, &(d3_t){r*4,0,0} },
+			{ type_rot_way, &(struct rot_way){
+			  .l=LINE_Y, .deg_way=WAY_V2(-90-sky_deg,90+sky_deg, half_sec,half_sec, 3) }},
+			{ type_slide, &(d3_t){0,0,-r} },
+			{ type_slice, &(struct slice){
+			  .n=3, .ds=(data_t[]){ { type_none }, spin, { type_none } },
+			  .ts=(double[]){ sky_sec+pipe_sec*2, sky_sec*2, pipe_sec*2+sky_sec} }},
+			{ type_end } }},
+		      .data = &(data_t){ type_square } }},
 		    { type_end } }} }};
 
 		data.type = type_arr;