I want to create aspect-aware contours (also called illuminated contours or Tanaka contours) for a map I have created in QGIS but finishing in Illustrator.
To do this I need the colour or luminosity of the contour lines to change depending on their azimuth or angle from northwest like this (done manually):
Is there a way to do this? Ideally without exploding the line into individual 2-vertex segments.