Circle Dragging IV

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Circle Dragging IV

✓ Published0🌍 Public

Last edited Jul 5, 2019

Created on May 11, 2016

This example demonstrates an improved method for dragging SVG circles, where the circle nearest to the pointer is selected for interaction rather than the topmost one. A Voronoi overlay, computed with `d3.voronoi`, is used for hit-testing, with its cells rendered as light-gray paths. Each circle is clipped to its corresponding Voronoi cell using a `clipPath`. During a drag, the `dragged` function updates the circle’s position and recalculates the Voronoi polygons. The code uses `d3.drag` for the interaction and `d3.scaleOrdinal` with `d3.schemeCategory20` for automatic circle colors.

AI-generated description

This is a variant of dragging SVG circles that uses better hit-testing. Rather than choose the top circle that contains the active pointer, this chooses the circle closest to the active pointer using a Voronoi overlay. This is similar to Tovi Grossman’s bubble cursor. (See also earlier D3 3.x examples by Andrew Couch, Christopher Manning and Nate Vack.)

The Voronoi diagram is shown with a light-gray stroke for demonstration purposes (and because it looks cool!); in real usage, you probably wouldn’t show it. You can refine this technique by clipping the Voronoi cells to a larger circle that surrounds the smaller draggable circles, or by performing a distance check in side drag.subject.

Compare this technique to searching for closest circle using Canvas.

gpl-3.0 Licensed

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