Subset mesh by vertex

Usage

vcg_subset_vertex(x, selector)

Arguments

x: surface mesh
selector: logical vector (must not contain NA), and length must be consistent with the number of vertices in x: which nodes are to be kept

Value

A triangular mesh of class 'mesh3d', a subset of x

Coercing Surface Inputs

The surface objects are converted to 'mesh3d' object before applying further calculations.

When surface is a surface ieegio object, the returned mesh3d$vb contains vertices that have been left-multiplied by surface$geometry$transforms[[1]] (the first transform stored in the geometry, typically the ScannerAnat or voxel-to-world transform).

Breaking change: Earlier versions (before 0.2.6) of ravetools returned the raw surface$geometry$vertices without applying any transform, so downstream code often multiplied by surface$geometry$transforms[[1]] (or an equivalent) manually before working in world space. Such code will now double apply the transform and produce incorrect coordinates. If you previously applied a transform from surface$geometry$transforms by hand after calling a ravetools mesh function on an 'ieegio_surface', remove that manual step.

Surfaces with an empty or missing geometry$transforms list (for example, surfaces produced by ieegio's volume_to_surface, which stores an identity transform) are unaffected.

If geometry$transforms contains multiple transforms targeting different coordinate spaces, only the first one is used. Callers that need a specific target space should select and apply that transform themselves before calling ravetools mesh functions.

Examples


sphere <- vcg_sphere()

nv <- ncol(sphere$vb)

selector <- seq_len(nv) > (nv / 2)

sub <- vcg_subset_vertex(sphere, selector)

if(is_not_cran()) {
  rgl_view({

    # subset sphere will be displayed in red
    rgl_call("shade3d", sub, col = 'red')

    # Original sphere will be displayed as wireframe
    rgl_call("wire3d", sphere, col = (2 - selector))

  })
}
#> Package `rgl` is not installed. Please install `rgl` to use this function.
#> Error in loadNamespace(name): there is no package called ‘rgl’