plyPlaneCut: Cut a PLY Mesh Along a Specified Plane (HTML widget; no Quartz)

Description

Cuts a mesh by a plane and returns either one side or both sides of the cut. The result is also previewed as an HTML widget (no Quartz/X11) with the kept side in solid color, the other side semi-transparent, and the cutting plane shown.

Usage

plyPlaneCut(
  plyFile,
  axis = "Z",
  vertIndex = NA,
  cut_value = NA,
  keepBoth = FALSE,
  plane = NA,
  flipAxis = FALSE,
  display = TRUE,
  kept_col = "#3C8DFF",
  other_col = "gray70",
  plane_col = "firebrick",
  plane_alpha = 0.35,
  main = "",
  widget_size_px = 768,
  scene_zoom = 1.5,
  leftOffset = 0,
  fieldofview = 0,
  title_font_size_px = 30,
  title_font_family =
    "system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif"
)

Value

If keepBoth = FALSE, a 'mesh3d' for the retained side. If keepBoth = TRUE, a list with elements 'meshA' and 'meshB'. The returned object also carries an attribute 'widget' with the htmltools::browsable preview when display = TRUE.

Arguments

plyFile: An object of class 'mesh3d'.
axis: Character, one of "X","Y","Z"; used when deriving the plane from a vertex index or a numeric cut value (ignored when 'plane' is supplied). Default "Z".
vertIndex: Integer index of a mesh vertex used to place an orthogonal plane through that vertex along 'axis'. Ignored if 'plane' or 'cut_value' is supplied.
cut_value: Numeric coordinate along 'axis' at which to place the orthogonal plane. Ignored if 'plane' is supplied. (HTML-friendly alternative to interactive pick)
keepBoth: Logical; if TRUE and the plane intersects the mesh, return both sides as a list with elements 'meshA' and 'meshB'. Default FALSE.
plane: Numeric vector c(a,b,c,d) giving a plane in ax + by + cz + d = 0 form. If provided, overrides 'axis', 'vertIndex', and 'cut_value'.
flipAxis: Logical; reverse the plane normal direction used to decide which side is kept when keepBoth = FALSE. Default FALSE.
display: Logical; if TRUE, render an HTML widget preview. Default TRUE.
kept_col: Color for the kept portion in the preview (default "#3C8DFF").
other_col: Color for the other portion in the preview (default "gray70").
plane_col: Color for the plane polygon in the preview (default "firebrick").
plane_alpha: Alpha for the plane polygon (default 0.35).
main: Plot title (default "")
widget_size_px: Square widget size in pixels (default 768)
scene_zoom: Initial zoom for the 3D scene (default 1.5)
leftOffset: Horizontal camera nudge (-1..1 recommended) (default 0)
fieldofview: Field of view in degrees (0 = isometric) (default 0)
title_font_size_px: Title font size in pixels (default 30)
title_font_family: CSS font-family list for the title (default system UI stack)

Details

This HTML-widget version avoids opening a native rgl window and mirrors the device-and-layout pattern you used in your updated DNE3d. Interactive vertex picking (select3d) isn’t supported in widget mode; supply the cut as plane, vertIndex + axis, or cut_value + axis. The kept side selection is controlled by the normal direction and flipAxis.