Find the topmost node drawn under a point — the picking primitive the retained
scene graph enables (base grid offers only grid.locator()). The scene is
compiled into a colour pick-buffer (each grob drawn in a colour encoding its
id, respecting clipping and paint order), so the result is geometry-, clip- and
overlap-exact. Markers and text are matched by their bounding box; lines and
segments by a small pick band.
Usage
hit_test(scene, x, y, units = c("npc", "px"))Arguments
- scene
A
vl_scene().- x, y
Query point, in
units:"npc"(default; the page,0..1with y up) or"px"(device pixels, top-left origin, y down).- units
"npc"or"px".