"crosshair" - mkraska/meclib GitHub Wiki

[ "crosshair","", [x0, y0], [xref, yref], [fx, fy], [dpx, dpy], snap]

Interactive crosshair for indicating or reading off co-ordinate values. The crosshair snaps to objects of type "line", "spline" and others (if they push components to the target list).

  • [x0,y0] initial location in standard grid units
  • [xref, yref] (optional, default: [0, 0]) origin of the co-ordinate display (infobox)
  • [fx, fy] (optional, default: [1, 1]) x and y values of a single grid unit (scaling factors)
  • [dpx, dpy] (optional, default: [1, 1]) decimal precision of the co-ordinate display
  • snap (optional, default: none) snap mode.
    • if missing: no snap to grid, just to targets
    • "grid" snap to grid with a snap according to dpx, dpy (1 means 0.1 grid spacing, 0 means snap to grid points)

Return value in names: scaled co-ordinates [x,y]

Objects:

  • p (point) control point of the crosshair

Usage examples:

  • picking coordinate values from function graphs
  • indicating locations of centroids
  • indication of reference points for moments

image

[
  [ "grid", "x","y", -5,5,-4,5, 50, [1,1], [0,0] ],
  [ "crosshair","", [1.5, 1] ]
]