ravetools (version 0.3.2)

vcg_update_normals: Update vertex normal

Description

Update vertex normal

Usage

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

Value

A 'mesh3d' object with normal vectors.

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

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)
})
}