Introduction to Interactive Radar Charts
In a UI for adjusting multi-dimensional parameters, radar charts (also known as spider graphs) are very intuitive. Being able to see the current balance at a glance through the area and shape of an octagon is more intuitive than having eight sliders lined up.
However, in many implementations, radar charts are read-only. Values are input through sliders, and the radar chart only displays the results. Taking it a step further, making it possible to directly drag the vertices of the radar chart would greatly improve the operation's feel. Moreover, if the sliders and radar chart are bidirectionally synchronized, users can operate from either side.
This article records the pattern for implementing SVG radar chart vertex drag editing and bidirectional synchronization with N sliders using React. Key points include coordinate transformation and pointer event handling.
Design Approach: One State, Two UIs
