added documentation

1 files changed, 8 insertions, 0 deletions

diff --git a/materials.py b/materials.py
index 4245212..4a8058f 100644
--- a/materials.py
+++ b/materials.py
@@ -1,4 +1,5 @@
 class Material(object):
+    """Material optical properties."""
     def __init__(self, name='none'):
         self.name = name
 
@@ -7,6 +8,13 @@ class Material(object):
         self.absorption_length = None
         self.scattering_length = None
 
+class Surface(object):
+    """Surface optical properties."""
+    def __init__(self, name='none'):
+        self.name = name
+
+        self.wavelength = None
+
 air = Material('air')
 h2o = Material('h2o')
 glass = Material('glass')