Select points from a scene

This function uses the select3d function to allow the user to choose a point or region in the scene, then reports on all the vertices in or near that selection.

Usage

selectpoints3d(objects = ids3d()$id, value = TRUE, closest = TRUE, <!-- % $ -->
               multiple = FALSE, ...)

Arguments

objects: A vector of object id values to use for the search.
value: If TRUE, return the coordinates of the points; otherwise, return their indices.
closest: If TRUE, return the points closest to the selection of no points are exactly within it.
multiple: If TRUE or a function, do multiple selections. See the Details below.
...: Other parameters to pass to select3d.

Details

The multiple argument may be a logical value or a function. If logical, it controls whether multiple selections will be performed. If multiple is FALSE, a single selection will be performed; it might contain multiple points. If TRUE, multiple selections will occur and the results will be combined into a single matrix.

If multiple is a function, it should take a single argument. This function will be called with the argument set to a matrix containing newly added rows to the value, i.e. it will contain coordinates of the newly selected points (if value = TRUE), or the indices of the points (if value = FALSE). It should return a logical value, TRUE to indicate that selection should continue, FALSE to indicate that it should stop.

In either case, if multiple selections are being performed, the ESC key will stop the process.

Value

If value is TRUE, a 3-column matrix giving the coordinates of the selected points. All rows in the matrix will be unique even if multiple vertices have the same coordinates.

If value is FALSE, a 2-column matrix containing columns:

id: The object id containing the point.
index: The index of the point within rgl.attrib(id, "vertices"). If multiple points have the same coordinates, all indices will be returned.

Note

This function selects points, not areas. For example, if the selection region is in the interior of the triangle, that will count as a miss for all of the triangle's vertices.

Author

Duncan Murdoch

Examples

xyz <- cbind(rnorm(20), rnorm(20), rnorm(20))
ids <- plot3d( xyz )

if (interactive() && !in_pkgdown_example()) {
  # Click near a point to select it and put a sphere there.
  # Press ESC to quit...

  # This version returns coordinates
  selectpoints3d(ids["data"], 
     multiple = function(x) {
        spheres3d(x, color = "red", alpha = 0.3, radius = 0.2)
        TRUE
     })

  # This one returns indices
  selectpoints3d(ids["data"], value = FALSE,
     multiple = function(ids) {
        spheres3d(xyz[ids[, "index"], , drop = FALSE], color = "blue", 
                  alpha = 0.3, radius = 0.2)
        TRUE
     })
}