Added functions to perform 'octahedral' encoding and decoding of normals.

See http://jcgt.org/published/0003/02/01/paper-lowres.pdf

examples/common/example.vert

@@ -1,20 +1,25 @@
-#version 140
-
-in vec4 position; // This will be the position of the vertex in model-space
-
-// The usual matrices are provided
-uniform mat4 cameraToClipMatrix;
-uniform mat4 worldToCameraMatrix;
-uniform mat4 modelToWorldMatrix;
-
-// This will be used by the fragment shader to calculate flat-shaded normals. This is an unconventional approach
-// but we use it in this example framework because not all surface extractor generate surface normals.
-out vec4 worldPosition;
-
-void main()
-{
-	// Standard sequence of OpenGL transformations.
-	worldPosition = modelToWorldMatrix * position;
-	vec4 cameraPosition = worldToCameraMatrix * worldPosition;
-	gl_Position = cameraToClipMatrix * cameraPosition;
-}
+#version 140
+
+in vec4 position; // This will be the position of the vertex in model-space
+in vec3 normal;
+
+// The usual matrices are provided
+uniform mat4 cameraToClipMatrix;
+uniform mat4 worldToCameraMatrix;
+uniform mat4 modelToWorldMatrix;
+
+// This will be used by the fragment shader to calculate flat-shaded normals. This is an unconventional approach
+// but we use it in this example framework because not all surface extractor generate surface normals.
+out vec4 worldPosition;
+out vec3 worldNormal;
+
+void main()
+{
+	// Standard sequence of OpenGL transformations.
+	worldPosition = modelToWorldMatrix * position;
+	vec4 cameraPosition = worldToCameraMatrix * worldPosition;
+	
+	worldNormal = normal;
+	
+	gl_Position = cameraToClipMatrix * cameraPosition;
+}