diff -urN wf-/data.c wf/data.c
--- wf-/data.c	2015-12-17 00:00:00.000000000 +0900
+++ wf/data.c	2015-12-19 00:00:00.000000000 +0900
@@ -212,6 +212,14 @@
 }
 
 static void
+op_data_timeshift(struct timeshift *ts, data_t *data, prm_t *prm)
+{
+	data_t op = { type_slide, &ts->slide };
+	prm->sec += ts->sec;
+	op_data_draw(&op, data, prm);
+}
+
+static void
 op_data_slide_way(struct way *slide, data_t *data, prm_t *prm)
 {
 	affin_t af;
@@ -224,6 +232,18 @@
 }
 
 static void
+op_data_rot_way(struct rot_way *rw, data_t *data, prm_t *prm)
+{
+	affin_t af;
+	struct way way = rw->deg_way;
+
+	way_get(&way, prm->sec);
+	affin_rot(&af, &rw->l, way.ret_v);
+	affin_compo(&prm->af, &prm->af, &af);
+	data_draw(data, prm);
+}
+
+static void
 op_data_copy(struct copy *copy, data_t *data, prm_t *prm)
 {
 	int x, y, z;
@@ -271,6 +291,20 @@
 	op_data_draw(&op, data, prm);
 }
 
+static void
+op_data_copy_timeshift(struct copy_timeshift *copy, data_t *data, prm_t *prm)
+{
+	int i;
+	struct timeshift ts = { .sec = copy->init_sec, .slide = copy->init };
+	data_t op = { type_timeshift, &ts };
+
+	for(i=0; i<copy->n; i++){
+		op_data_draw(&op, data,prm);
+		ts.sec += copy->step_sec;
+		d3_add(&ts.slide, &copy->step);
+	}
+}
+
 void
 op_data_draw(data_t *op, data_t *data, prm_t *prm)
 {
@@ -299,15 +333,16 @@
 	case type_mirror:
 		op_data_mirror(op->p, data, prm);
 		break;
+	case type_timeshift:
+		op_data_timeshift(op->p, data, prm);
+		break;
 
 	case type_slide_way:
 		op_data_slide_way(op->p, data, prm);
 		break;
-#if 0
 	case type_rot_way:
 		op_data_rot_way(op->p, data, prm);
 		break;
-#endif
 
 	case type_copy:
 		op_data_copy(op->p, data, prm);
@@ -321,6 +356,9 @@
 	case type_copy_mirror:
 		op_data_copy_mirror(op->p, data, prm);
 		break;
+	case type_copy_timeshift:
+		op_data_copy_timeshift(op->p, data, prm);
+		break;
 
 	case type_end:
 	default:
diff -urN wf-/data.h wf/data.h
--- wf-/data.h	2015-12-17 00:00:00.000000000 +0900
+++ wf/data.h	2015-12-19 00:00:00.000000000 +0900
@@ -25,6 +25,7 @@
 #define type_rot			103
 #define type_point_symmetry		104
 #define type_mirror			105
+#define type_timeshift			106
 
 #define type_slide_way			120
 #define type_rot_way			130
@@ -33,6 +34,7 @@
 #define type_copy_rot			201
 #define type_copy_point_symmetry	202
 #define type_copy_mirror		203
+#define type_copy_timeshift		204
 
 
 struct wire_frame{
@@ -53,6 +55,16 @@
 	double deg;
 };
 
+struct rot_way{
+	line_t l;
+	struct way deg_way;
+};
+
+struct timeshift{
+	double sec;
+	d3_t slide;
+};
+
 struct copy{
 	struct { int x, y, z; } n;
 	d3_t init, step;
@@ -66,6 +78,12 @@
 	/* deg = init_deg + step_deg * i */
 };
 
+struct copy_timeshift{
+	int n;
+	double init_sec, step_sec;
+	d3_t init, step;
+};
+
 typedef struct{
 	affin_t af;
 	const eye_t *eye;
diff -urN wf-/way.c wf/way.c
--- wf-/way.c	2015-12-17 00:00:00.000000000 +0900
+++ wf/way.c	2015-12-19 00:00:00.000000000 +0900
@@ -37,7 +37,8 @@
 		sum += ts[i];
 	}
 	*t -= sum;
-	*t /= ts[i];
+	if(ts[i] == 0) *t = 0;
+	else *t /= ts[i];
 	return i;
 }
 
@@ -66,10 +67,10 @@
 
 			for(i=0; i<3; i++) k[i] = way->vs[(idx+i)%n] - way->vs[(prv+i)%n];
 
-			if(!is_repeat(ts, n) && idx == 0) ksp = NULL;
+			if((!is_repeat(ts, n) && idx == 0) || ts[prv] == 0) ksp = NULL;
 			else ks = ( k[0] * ts[idx] / ts[prv] + k[1] ) * 0.5;
 
-			if(!is_repeat(ts, n) && idx == n-2) kep = NULL;
+			if((!is_repeat(ts, n) && idx == n-2) || ts[nxt] == 0) kep = NULL;
 			else ke = ( k[1] + k[2] * ts[idx] / ts[nxt] ) * 0.5;
 
 			way->ret_v = interp3(way->vs[idx], way->vs[nxt], ksp, kep, t);
@@ -80,7 +81,7 @@
 			for(i=0; i<3; i++) vec_set(&k[i], &way->ps[(prv+i)%n], &way->ps[(idx+i)%n]);
 
 
-			if(!is_repeat(ts, n) && idx == 0) ksp = NULL;
+			if((!is_repeat(ts, n) && idx == 0) || ts[prv] == 0) ksp = NULL;
 			else{
 				ks = k[0];
 				d3_mul(&ks, ts[idx] / ts[prv]);
@@ -88,7 +89,7 @@
 				d3_mul(&ks, 0.5);
 			}
 
-			if(!is_repeat(ts, n) && idx == n-2) kep = NULL;
+			if((!is_repeat(ts, n) && idx == n-2) || ts[nxt] == 0) kep = NULL;
 			else{
 				ke = k[2];
 				d3_mul(&ke, ts[idx] / ts[nxt]);
diff -urN wf-/wf_ex.c wf/wf_ex.c
--- wf-/wf_ex.c	2015-12-18 00:00:00.000000000 +0900
+++ wf/wf_ex.c	2015-12-19 00:00:00.000000000 +0900
@@ -200,11 +200,16 @@
                     .ts = (double[]){1,1,1,1}, .dg = 3 }},
 		  .data = &(data_t){ type_cube } }};
 
+		data_t *cube3 = &(data_t){ type_op_data_set, &(struct op_data_set){
+		  .op = &(data_t){ type_copy_timeshift, &(struct copy_timeshift){
+		    .n = 3, .init_sec = 0, .step_sec = -0.3, .init = {0,0,0}, .step = {0,0,0} } },
+		  .data = cube2 }};
+
 		data.type = type_arr;
 		data.p = (data_t[]){
 			*axyz,
 			*cross,
-			*cube, *cube2,
+			*cube, *cube3,
 			{ type_end }
 		};
 	}