c++ - Drawing a line with a gradient color in OpenCV -

i found question different technologies not using opencv in c++. need draw line changes color in order represent direction 1 color starts , finishes, visually can see direction of several trajectories have. each trajectory has several points, not same amount.

i assume want different colors each direction? would pick reference line horizontal one. , calculate angle between each line , horizontal line. map 255 value 360 degree example color=255/360*anglefound. put value cv::line function. cv::line( , , rgb(color,color,color)). example. can put color value in different ways. in way each direction have own color.