add a small comment explaining the colorization

1 files changed, 9 insertions, 0 deletions

diff --git a/fietsboek/trackmap.py b/fietsboek/trackmap.py
index d2f16e0..cb64893 100644
--- a/fietsboek/trackmap.py
+++ b/fietsboek/trackmap.py
@@ -212,6 +212,14 @@ def height_profile(track: geo.Path, size: tuple[int, int] = (300, 300), simplify
         polyline.append((cur_x, cur_y, dist, point.elevation))
         last = point
 
+    # If simplification is enabled, we do the following:
+    # 1. We use the Visvalignam-Whyatt algorithm to simplify the height profile
+    #    to the given number of points.
+    # 2. We colorize the simplified profile.
+    # 3. We draw the actual profile using the original data, only using the
+    #    simplified color profile for the colors.
+    # This gives the best of both worlds: An accurately drawn profile, but no
+    # color "overload".
     if simplify:
         simplified = _visvalignam_whyatt(polyline, simplify)
     else:
@@ -253,6 +261,7 @@ def _visvalignam_whyatt(
     polyline: list[tuple[float, float, float, float]],
     target: int,
 ) -> list[tuple[float, float, float, float]]:
+    # See https://en.wikipedia.org/wiki/Visvalingam%E2%80%93Whyatt_algorithm
     polyline = polyline[:]
     while len(polyline) > target:
         areas = (