homework2, render opencv 3d logo, support shade flat/smooth and smoothing group

Author: sleeplessai

assets/opencvpart.obj

@@ -502,6 +502,7 @@ vt 0.000000 0.000000
 vt 0.000000 0.000000
 vt 0.000000 0.000000
 s 0
+#group 0
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@@ -555,6 +556,7 @@ f 45/45/1 44/44/1 98/98/1 99/99/1
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+#group 1
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@@ -608,6 +610,7 @@ f 153/153/2 207/207/2 206/206/2 152/152/2
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+#group 2
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@@ -661,6 +664,7 @@ f 51/51/52 52/52/52 160/160/52 159/159/52
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+#group 3
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@@ -714,5 +718,7 @@ f 106/106/20 105/105/20 213/213/20 214/214/20
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+#group 4
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+#group 5
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