diff -urN rt_v8/cg.py rt_v9/cg.py
--- rt_v8/cg.py	2018-03-22 13:58:02.000000000 +0900
+++ rt_v9/cg.py	2018-03-23 11:46:23.000000000 +0900
@@ -54,21 +54,19 @@
 	copen = 'copen-090419.jpg'
 	beat = 'beat.jpg'
 
-	rtd = { 'base': 1.0, 'diff': 0 }
-
 	maps = [
 		{ 'fn': 'IMG_3999_3.mov', 'fn_r': 'IMG_3999_4.mov', 't2m': [ ax.zoom_all(3) ] },
 	]
 
 	data = [ {
 		'kind': 'square',
-		'rtd': rtd,
+		'rtd': { 'base': 0.1, 'diff': 1.0, 'reflect': 0.9 },
 		'l2m': [],
 		'maps': maps,
 		'm2g': [ ax.zoom_all(50) ],
 	},{
 		'kind': 'ball',
-		'rtd': { 'base':0.1, 'diff': 0, 'reflact': 0.5, 'density': 2 },
+		'rtd': { 'base':0.1, 'diff': 0, 'reflect': 0.5, 'reflact': 0.5, 'density': 2 },
 		'def_col': [128,0,0],
 		'l2m': [ ax.zoom_all(20.0/50) ],
 		'm2g': [ ax.zoom_all(50) ],
@@ -77,7 +75,8 @@
 	data = sum( map( d_setup, data ), [] )
 
 	lights = [
-		{ 'v': [0,0,-1], 'e': 1.0 },
+		{ 'p': v.op1( '*', [1,-1,-1], 30 ), 'e': 2.5 },
+		{ 'p': v.op1( '*', [-1,1,1], 30 ), 'e': 2.5 },
 	]
 
 	(w, h) = ( ut.arg_i('w', 640) , ut.arg_i('h', 480) )
diff -urN rt_v8/rt.py rt_v9/rt.py
--- rt_v8/rt.py	2018-03-21 21:20:02.000000000 +0900
+++ rt_v9/rt.py	2018-03-23 11:23:36.000000000 +0900
@@ -69,15 +69,14 @@
 			return 0
 
 		def f(ltd):
-			ltv = [0,0,1]
-			if 'v' in ltd:
-				ltv = v.nega( ltd.get('v') )
-			elif 'p' in ltd:
-				ltv = v.sub_unit( ltd.get('p'), crsp )
+			ltv = ltd.get( 'v', [0,0,-1] )
+			if 'p' in ltd:
+				ltv = v.sub_unit( crsp, ltd.get('p') )
 			ang_nv_lt = v.dot_product( nv, ltv )
-			if ang_nv_eyev_nega * ang_nv_lt < 0:
+			ang_nv_lt_nega = -ang_nv_lt
+			if ang_nv_eyev_nega * ang_nv_lt_nega < 0:
 				return 0
-			return max( ang_nv_lt, 0 ) * ltd.get('e', 1.0)
+			return abs( ang_nv_lt ) * ltd.get('e', 1.0)
 
 		return sum( map( f, lights ) ) * diff
 
@@ -88,6 +87,8 @@
 		reflect = rtd.get('reflect', 0)
 		if not reflect:
 			return []
+		if ang_nv_eyev_nega < 0 and not rtd.get('reflect_backside', False):
+			return []
 		ref_v = v.op2( '+', v.op1( '*', nv, 2 * ang_nv_eyev_nega ), eyev )
 		ref_l = line.new( crsp, ref_v )
 		col = get_col( data, lights, ref_l, video, nest_rate * reflect, crst )
diff -urN rt_v8/ut.py rt_v9/ut.py
--- rt_v8/ut.py	2018-03-16 20:38:43.000000000 +0900
+++ rt_v9/ut.py	2018-03-23 11:00:56.000000000 +0900
@@ -4,6 +4,7 @@
 import os
 import time
 import subprocess
+from decimal import *
 
 arg_s = lambda k, def_val='': next( ( s[ len(k)+1: ] for s in sys.argv if s.startswith(k+'=') ), def_val )
 arg_v = lambda fs, k, def_val: ( lambda s: fs(s) if s else def_val )( arg_s(k) )
@@ -54,6 +55,7 @@
 	si = int(sec)
 	m = si / 60
 	s = si % 60 + int( (sec - si) * 100 ) * 0.01
+	s = Decimal(s).quantize( Decimal('1.00') )
 	h = m / 60
 	m %= 60
 	lst = [ (s, 's') ]