fix markers on lines with variable aesthetics - Githubissues

observablehq / plot

A concise API for exploratory data visualization implementing a layered grammar of graphics

https://observablehq.com/plot/

ISC License

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fix markers on lines with variable aesthetics #2094

Closed Fil closed 1 day ago

Fil commented 1 month ago

for lines with variable aesthetics we want to maintain the higher-level semantics of markers:

markerStart matches the start of the line
markerMid matches the points which are not at the start or the end
markerEnd matches the end of the line

Since these lines are implemented as multiple paths, we need to change the low-level implementation of markers:

markerStart only applies to the first segment of a line
markerMid applies to all the segments, complemented by the start of all but the first segments
markerEnd only applies to the last segment of a line

closes #2093