Updated comments to specify the position of points (#141)

Updated comments to specify the position of points on the face for 68 points generated by the face landmark detector.

dlib/image_processing/render_face_detections.h

@@ -25,32 +25,42 @@ namespace dlib
             );
 
             const full_object_detection& d = dets[i];
+            // Around Chin. Ear to Ear
             for (unsigned long i = 1; i <= 16; ++i)
                 lines.push_back(image_window::overlay_line(d.part(i), d.part(i-1), color));
                 
+            // Line on top of nose
             for (unsigned long i = 28; i <= 30; ++i)
                 lines.push_back(image_window::overlay_line(d.part(i), d.part(i-1), color));
             
+            // left eyebrow
             for (unsigned long i = 18; i <= 21; ++i)
                 lines.push_back(image_window::overlay_line(d.part(i), d.part(i-1), color));
+            // Right eyebrow
             for (unsigned long i = 23; i <= 26; ++i)
                 lines.push_back(image_window::overlay_line(d.part(i), d.part(i-1), color));
+            // Bottom part of the nose
             for (unsigned long i = 31; i <= 35; ++i)
                 lines.push_back(image_window::overlay_line(d.part(i), d.part(i-1), color));
+            // Line from the nose to the bottom part above
             lines.push_back(image_window::overlay_line(d.part(30), d.part(35), color));
 
+            // Left eye
             for (unsigned long i = 37; i <= 41; ++i)
                 lines.push_back(image_window::overlay_line(d.part(i), d.part(i-1), color));
             lines.push_back(image_window::overlay_line(d.part(36), d.part(41), color));
 
+            // Right eye
             for (unsigned long i = 43; i <= 47; ++i)
                 lines.push_back(image_window::overlay_line(d.part(i), d.part(i-1), color));
             lines.push_back(image_window::overlay_line(d.part(42), d.part(47), color));
 
+            // Lips outer part
             for (unsigned long i = 49; i <= 59; ++i)
                 lines.push_back(image_window::overlay_line(d.part(i), d.part(i-1), color));
             lines.push_back(image_window::overlay_line(d.part(48), d.part(59), color));
 
+            // Lips inside part
             for (unsigned long i = 61; i <= 67; ++i)
                 lines.push_back(image_window::overlay_line(d.part(i), d.part(i-1), color));
             lines.push_back(image_window::overlay_line(d.part(60), d.part(67), color));