I am trying to have a gx:track's line to have different colour in different part in the track depending on some conditions, but I am unable to find way to colour part of a track. I am using C# to generate the kml file. BTW my gx:track's has extendedData.
I know I can apply lineStyle to the gx:track but that will only apply to the whole track, but I would like to have different colour along the track's line.
Thanks in advance.
Terry
As previous answer says, you have to split track into segments and color each segment individually. There is no other way to do this using KML. But remember that this can create very large KML files for long tracks! So try to save some space by using shared styles.
I would recommend creating one "gx:track" with low "draworder" for whole track and collection of placemarks with different colors and high "draworder" for every small segment of track.
You can examine results of this approach here: http://www.zonefivesoftware.com/sporttracks/plugins/?p=dobrou-extensions (it is a plugin for application SportTracks).
It's my tool for visualization of GPS tracks. It does track coloring by creating placemark, with own color style, for every track segment.
Here you can see examples tracks colored in KML:
Track colored by elevation KMZ
As you discovered, you can only style complete tracks. If you want different segments to have different colors, you need to break the track up, then style each segment.
I used simplekml which uses Python to generate KML code. As the other answers point out you have to split the line into multiple linestrings each of which has a different style. You can use a common set of styles for making the size of kml smaller though.
the end coordinates of one line is the start coordinates of the next line.
来源：https://stackoverflow.com/questions/11874858/colorise-single-track-in-kml-file