Make layer distance changable. Refs #1.

As a side-effet, now the ordering of the layers is left-to-right rather
than right-to-left. This shouldn't matter in normal processing, but it
is interesting nonetheless.

src/fmri/Options.cpp

@@ -16,6 +16,24 @@ static void check_file(const std::string& filename)
     }
 }
 
+/**
+ * Create a boost::program_options::value for some variable.
+ *
+ * Utility method to make generating value wrappers less repetitive. This
+ * method automatically sets the default value to whatever the variable
+ * currently holds.
+ *
+ * @tparam T
+ * @param val Variable to be set/use as default.
+ * @return A value wrapper
+ */
+template<typename T>
+inline static auto value_for(T& val)
+{
+    return boost::program_options::value<T>(&val)
+            ->default_value(val);
+}
+
 /**
  * Parse a color string into a color array.
  *
@@ -70,9 +88,10 @@ Options::Options(int argc, char * const argv[]):
                 ("network,n", value<std::string>(&modelPath)->required(), "caffe model file for the network")
                 ("labels,l", value<std::string>(&labelsPath), "labels file")
                 ("means,m", value<std::string>(&meansPath), "means file")
-                ("path-color,p", value<std::string>(), "color for paths")
-                ("layer-opacity", value<float>(&layerTransparancy_), "Opacity for layers")
-                ("interaction-opacity", value<float>(&interactionTransparancy_), "Opacity for interactions")
+                ("path-color,p", value<std::string>()->default_value("#ffffff19"), "color for paths")
+                ("layer-opacity", value_for(layerTransparancy_), "Opacity for layers")
+                ("interaction-opacity", value_for(interactionTransparancy_), "Opacity for interactions")
+                ("layer-distance", value_for(LAYER_X_OFFSET), "Distance between layers")
                 ("dump,d", value<std::string>(&dumpPath), "dump convolutional images in this directory");
 
         options_description composed = desc;

src/fmri/RenderingState.cpp

@@ -236,7 +236,7 @@ void RenderingState::render(float time) const
 
 
     glPushMatrix();
-    glTranslatef(5 * currentData->size(), 0, 0);
+    glTranslatef(-LAYER_X_OFFSET / 2 * currentData->size(), 0, 0);
 
     for (auto i : Range(currentData->size())) {
         glPushMatrix();

src/fmri/utils.cpp

@@ -1,7 +1,7 @@
 #include <caffe/util/math_functions.hpp>
 #include "utils.hpp"
 
-const float fmri::LAYER_X_OFFSET = -10;
+float fmri::LAYER_X_OFFSET = 10;
 
 std::default_random_engine &fmri::rng()
 {

src/fmri/utils.hpp

@@ -21,8 +21,10 @@ namespace fmri
 
     /**
      * The distance between layers in the visualisation.
+     *
+     * This value is set from the options parser when provided.
      */
-	extern const float LAYER_X_OFFSET;
+	extern float LAYER_X_OFFSET;
 
     constexpr const float EPSILON = 1e-10f;