slicify: fct comment

Resample/Processed/ReSample.cpp

@@ -99,10 +99,15 @@ void checkVolumeFractions(const Admixtures& admixtures)
                                  "total volumetric fraction of particles exceeds 1!");
 }
 
-//! Returns a SliceStack that refines the layer structure of sample,
-//! taking into account the average SLD of layer material and particle decoration.
+//! Returns a vector of slices that represent the layer structure of the sample.
 //!
-//! For use in ReSample constructor.
+//! Each slice is either a layer, or a fraction of a layer.
+//! Layers are fractioned into several slices if
+//! - option useAvgMaterials is true,
+//! - layer->numberOfSlices > 1, and
+//! - there are particles in the layer.
+//!
+//! Used in ReSample constructor.
 
 SliceStack slicify(const MultiLayer& sample, const SimulationOptions& options)
 {
@@ -124,7 +129,7 @@ SliceStack slicify(const MultiLayer& sample, const SimulationOptions& options)
                 roughness = nullptr;
 
             if (i == nLayers - 1)
-                tl = 0.0;
+                ASSERT(tl == 0);
             if (i == 0)
                 result.addTopSlice(tl, *material);
             else