vcg_update_normals: Update vertex normal

In ravetools: Signal and Image Processing Toolbox for Analyzing Intracranial Electroencephalography Data

Update vertex normal

Description

Update vertex normal

Usage

vcg_update_normals(
  mesh,
  weight = c("area", "angle"),
  pointcloud = c(10, 0),
  verbose = FALSE
)

Arguments

mesh	triangular mesh or a point-cloud (matrix of 3 columns)
weight	method to compute per-vertex normal vectors: "area" weighted average of surrounding face normal, or "angle" weighted vertex normal vectors.
pointcloud	integer vector of length 2: containing optional parameters for normal calculation of point clouds; the first entry specifies the number of neighboring points to consider; the second entry specifies the amount of smoothing iterations to be performed.
verbose	whether to verbose the progress

Value

A 'mesh3d' object with normal vectors.

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

if(is_not_cran()) {

# Prepare mesh with no normal
data("left_hippocampus_mask")
mesh <- vcg_isosurface(left_hippocampus_mask)
mesh$normals <- NULL

# Start: examples
new_mesh <- vcg_update_normals(mesh, weight = "angle",
                               pointcloud = c(10, 10))

rgl_view({
  rgl_call("mfrow3d", 1, 2)
  rgl_call("shade3d", mesh, col = 2)

  rgl_call("next3d")
  rgl_call("shade3d", new_mesh, col = 2)
})
}

ravetools documentation built on May 31, 2026, 9:06 a.m.