SurfaceGeometry: Create a SurfaceGeometry Object

In bbuchsbaum/neurosurf: Data structures and visualization for surface-based neuroimaging data

Create a SurfaceGeometry Object

Description

This function creates a new SurfaceGeometry object from vertex coordinates and face indices.

Usage

SurfaceGeometry(vert, faces, hemi)

Arguments

vert	A numeric matrix with 3 columns representing the x, y, and z coordinates of vertices.
faces	An integer matrix where each row represents a face, containing indices of vertices that form the face.
hemi	A character string indicating the hemisphere ("lh" for left, "rh" for right, or other identifier).

Details

This function constructs a SurfaceGeometry object by creating a mesh and a graph representation of the surface. It uses the rgl package for 3D visualization and the igraph package for graph operations.

The vertex indices in the faces matrix should be 0-based (starting from 0), as they get incremented by 1 when passed to the rgl mesh function.

Value

A new object of class "SurfaceGeometry" containing:

mesh	An rgl mesh object representing the surface.
graph	An igraph object representing the mesh connectivity.
hemi	The hemisphere identifier.

Examples

# Create a simple icosahedron-like mesh with 12 vertices
set.seed(123)
vertices <- matrix(rnorm(36), ncol=3)

# Create faces with 0-based indices (0 to 11)
# Each face connects three vertices
faces <- matrix(sample(0:11, 60, replace=TRUE), ncol=3)

# Create the SurfaceGeometry object
surf_geom <- SurfaceGeometry(vertices, faces, "lh")

# Visualize the mesh if rgl is available
if(requireNamespace("rgl", quietly = TRUE)) {
  rgl::open3d()
  rgl::shade3d(surf_geom@mesh, col="lightblue")
}

bbuchsbaum/neurosurf documentation built on June 10, 2025, 8:22 p.m.