Edit a mesh

lari_add_points() inserts points (a point on a constraint splits it) and returns their vertex ids. lari_add_segments() inserts constraints between existing vertex ids, inserting the crossing point where they cross existing constraints, and returns the new segment ids. lari_remove_points() removes vertices, along with any segment that ends at them. lari_remove_segments() removes constraints by their end vertex ids (or by segment id with id); crossing vertices that no longer lie on any constraint are removed too, so adding and then removing a segment leaves the tables as they were.

Usage

lari_add_points(m, x, y, PA = NULL)

lari_add_segments(m, s0, s1)

lari_remove_points(m, ids)

lari_remove_segments(m, s0 = NULL, s1 = NULL, id = NULL)

Arguments

m

a mesh from lari_new()

x, y

point coordinates

PA

attribute matrix, one row per point, with the mesh's columns

s0, s1

vertex ids of segment ends

ids

vertex ids

id

segment ids (alternative to s0/s1)

Value

lari_add_points(): integer vertex ids. lari_add_segments(): integer segment ids (NA for a zero-length segment). The removers return the number removed, invisibly.

Details

Any edit discards the mesher state: the next lari_refine() or lari_step() starts a new mesher on the edited triangulation (which only finds bad triangles where the edit made them).

Examples

m <- lari_new(c(0, 1, 1, 0), c(0, 0, 1, 1))
ids <- lari_add_points(m, 0.5, 0.5)
lari_add_segments(m, c(1, 2), c(3, 4))    ## crossing diagonals
#> [1] 1 2
lari_vertices(m)
#>     x   y origin id
#> 1 0.0 0.0  input  1
#> 2 1.0 0.0  input  2
#> 3 1.0 1.0  input  3
#> 4 0.0 1.0  input  4
#> 5 0.5 0.5  input  5
lari_remove_segments(m, 2, 4)
lari_vertices(m)
#>     x   y origin id
#> 1 0.0 0.0  input  1
#> 2 1.0 0.0  input  2
#> 3 1.0 1.0  input  3
#> 4 0.0 1.0  input  4
#> 5 0.5 0.5  input  5