fm_bary: Compute barycentric coordinates

In fmesher: Triangle Meshes and Related Geometry Tools

Compute barycentric coordinates

Description

Identify knot intervals or triangles and compute barycentric coordinates

Usage

fm_bary(...)

## S3 method for class 'fm_bary'
fm_bary(bary, ..., extra_class = NULL)

## S3 method for class 'list'
fm_bary(bary, ..., extra_class = NULL)

## S3 method for class 'tbl_df'
fm_bary(bary, ..., extra_class = NULL)

## S3 method for class 'fm_mesh_1d'
fm_bary(mesh, loc, method = c("linear", "nearest"), restricted = FALSE, ...)

## S3 method for class 'fm_mesh_2d'
fm_bary(mesh, loc, crs = NULL, ..., max_batch_size = NULL)

## S3 method for class 'fm_mesh_3d'
fm_bary(mesh, loc, ..., max_batch_size = NULL)

## S3 method for class 'fm_lattice_2d'
fm_bary(mesh, loc, crs = NULL, ...)

## S3 method for class 'fm_lattice_Nd'
fm_bary(mesh, loc, ...)

Arguments

...	Arguments forwarded to sub-methods.
bary	An fm_bary object, or an object that can be converted to fm_bary.
extra_class	character; If non-NULL and not already in the class vector of bary, add it to the front of the class vector.
mesh	fm_mesh_1d or fm_mesh_2d object
loc	Points for which to identify the containing interval/triangle, and corresponding barycentric coordinates. May be a vector (for 1d) or a matrix of raw coordinates, sf, or sp point information (for 2d).
method	character; method for defining the barycentric coordinates, "linear" (default) or "nearest"
restricted	logical, used for method="linear". If FALSE (default), points outside the mesh interval will be given barycentric weights less than 0 and greater than 1, according to linear extrapolation. If TRUE, the barycentric weights are clamped to the (0, 1) interval.
crs	Optional crs information for loc
max_batch_size	integer; maximum number of points to process in a single batch. This speeds up calculations by avoiding repeated large internal memory allocations and data copies. The default, NULL, uses max_batch_size = 2e5L, chosen based on empirical time measurements to give an approximately optimal runtime.

Value

A fm_bary object, a tibble with columns index; either

• vector of triangle indices (triangle meshes),

• vector of knot indices (1D meshes, either for edges or individual knots), or

• vector of lower left box indices (2D lattices),

and where, a matrix of barycentric coordinates.

Methods (by class)

• fm_bary(fm_bary): Returns the bary input unchanged

• fm_bary(list): Converts a list bary to fm_bary. In the list elements are unnamed, the names index and where are assumed.

• fm_bary(tbl_df): Converts a tibble::tibble() bary to fm_bary

• fm_bary(fm_mesh_1d): Return an fm_bary object with elements index (edge index vector pointing to the first knot of each edge) and where (barycentric coordinates, 2-column matrices). Use fm_bary_simplex() to obtain the corresponding endpoint knot indices.

  For method = "nearest", index contains the index of the nearest mesh knot, and where is a single-column all-ones matrix.

• fm_bary(fm_mesh_2d): An fm_bary object with columns index (vector of triangle indices) and where (3-column matrix of barycentric coordinates). Points that were not found give NA entries in index and where.

• fm_bary(fm_mesh_3d): An fm_bary object with columns index (vector of triangle indices) and where (4-column matrix of barycentric coordinates). Points that were not found give NA entries in index and where.

• fm_bary(fm_lattice_2d): An fm_bary object with columns index (vector of lattice cell indices) and where (4-column matrix of barycentric coordinates). Points that are outside the lattice are given NA entries in index and where.

• fm_bary(fm_lattice_Nd): An fm_bary object with columns index (vector of lattice cell indices) and where 2^d-column matrix of barycentric coordinates). Points that are outside the lattice are given NA entries in index and where.

See Also

fm_bary_simplex(), fm_bary_loc()

Examples

bary <- fm_bary(fm_mesh_1d(1:4), seq(0, 5, by = 0.5))
bary
str(fm_bary(fmexample$mesh, fmexample$loc_sf))
m <- fm_mesh_3d(
  rbind(
    c(1, 0, 0),
    c(0, 1, 0),
    c(0, 0, 1),
    c(0, 0, 0)
  ),
  matrix(c(1, 2, 3, 4), 1, 4)
)
b <- fm_bary(m, matrix(c(1, 1, 1) / 4, 1, 3))
str(fm_bary(fmexample$mesh, fmexample$loc_sf))

fmesher documentation built on Aug. 9, 2025, 1:10 a.m.