documentaiton updates

src/medium/heterogeneous.cpp

@@ -69,7 +69,7 @@ static StatsCounter earlyExits("Heterogeneous volume",
  *         Volumetric data source that supplies the 
  *         single-scattering albedo
  *     }
- *     \parameter{orientations}{\Volume}{
+ *     \parameter{orientation}{\Volume}{
  *         Optional: volumetric data source that supplies the 
  *         local particle orientations throughout the medium
  *     }

src/volume/constvolume.cpp

@@ -33,11 +33,18 @@ MTS_NAMESPACE_BEGIN
  * its value can either be a scalar, a color spectrum,
  * or a 3D vector.
  *
- * \begin{xml}[caption={Definition of a heterogeneous medium with constant albedo}]
+ * \begin{xml}[caption={Definition of a heterogeneous medium with homogeneous contents}]
+ *   constant albedo}]
  * <medium type="heterogeneous">
+ *     <volume type="constvolume" name="density">
+ *         <float name="value" value="1"/>
+ *     </volume>
  *     <volume type="constvolume" name="albedo">
  *         <rgb name="value" value="0.9 0.9 0.7"/>
  *     </volume>
+ *     <volume type="constvolume" name="orientation">
+ *         <vector name="value" x="0" y="1" z="0"/>
+ *     </volume>
  *
  *     <!-- .... remaining parameters for 
  *          the 'heterogeneous' plugin -->

src/volume/volcache.cpp

@@ -51,13 +51,15 @@ struct Vector3iKeyOrder : public std::binary_function<Vector3i, Vector3i, bool>
  *     }
  *     \parameter{voxelWidth}{\Float}{
  *         Width of a voxel (in a cache block) expressed in
- *         world-space units. \default{automatic}
+ *         world-space units. \default{set to the ray marching
+ *         step size of the nested medium}
  *     }
  *     \parameter{memoryLimit}{\Integer}{
- *         Max. allowed memory usage in MiB. \default{1024, i.e. 1 GiB}
+ *         Maximum allowed memory usage in MiB. \default{1024, i.e. 1 GiB}
  *     }
  *     \parameter{toWorld}{\Transform}{
- *         Optional linear transformation that should be applied to the data
+ *         Optional linear transformation that should be applied 
+ *         to the volume data
  *     }
  *     \parameter{\Unnamed}{\Volume}{
  *         A nested volume data source