added scenes/trans-boxes.fart, changed Scene to consider all back-faces as front-faces by inverting the normal vector, fixed bug in Scene::calculateLightContribution() which was messing up shadow values and back-face intensities for transparent objects

git-svn-id: svn://anubis/fart/trunk@187 7f9b0f55-74a9-4bce-be96-3c2cd072584d

scenes/trans-boxes.fart

@@ -0,0 +1,46 @@
+
+scene
+{
+    options
+    {
+        width 800
+        height 600
+        multisample 3
+    }
+
+    camera
+    {
+        position <3, -4, 4>
+        look_at <0, 0, 0>
+        up <0, 0, 1>
+    }
+
+    light { position <5, -2, 5> }
+
+    plane
+    {
+        position <0, 0, 1>, 0
+        material { color <0.8, 0.8, 0.8> }
+    }
+
+    box
+    {
+        size <1, 1, 1>
+        translate <0, -1.5, 0.6>
+        material { color <0, 0, 1> transparency 0.8 }
+    }
+
+    box
+    {
+        size <1, 1, 1>
+        translate <0, 0, 0.6>
+        material { color <0, 0, 1> transparency 0.4 }
+    }
+
+    box
+    {
+        size <1, 1, 1>
+        translate <0, 1.5, 0.6>
+        material { color <0, 0, 1> transparency 0.1 }
+    }
+}