Construct a triangle pool — new_wkpool

A low-level constructor for wkpool_tri objects: a vector of triangles whose corners are vertex ids into a shared vertex pool, the same pool structure a wkpool uses for segments.

Usage

new_wkpool_tri(
  vertices,
  vx0,
  vx1,
  vx2,
  feature = NULL,
  part = NULL,
  paths = NULL,
  crs = NULL,
  geodesic = FALSE
)

Arguments

vertices: A data.frame with columns .vx (integer vertex ids), x, y, and optionally z.
vx0, vx1, vx2: Integer vectors of triangle corner vertex ids, each value present in vertices$.vx.
feature: Optional integer vector of feature ids, one per triangle.
part: Optional integer vector of part ids, one per triangle (the polygon within a multipolygon feature, as identified by wk::wk_coords()).
paths: Optional data.frame describing the input paths (see pool_paths()), carried from the segment pool.
crs: A CRS object (commonly an authority string such as "EPSG:4326"), carried but never interpreted, per wk's CRS propagation model. Use NULL for none, or wk::wk_crs_inherit().
geodesic: TRUE if segments should be interpreted as geodesics when coordinates are spherical, FALSE otherwise, NA to inherit.

Value

A wkpool_tri object.

Details

The wkpool_tri class is experimental: how a triangle records the polygon part it came from (currently a .part field) may change in a later release.

Examples

v <- data.frame(.vx = 1:4, x = c(0, 1, 1, 0), y = c(0, 0, 1, 1))
new_wkpool_tri(v, vx0 = c(1L, 1L), vx1 = c(2L, 3L), vx2 = c(3L, 4L))
#> <wkpool_tri[2 triangles, 4 vertices]>
#> [1] <triangle: 1,2,3> <triangle: 1,3,4>