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Mesh tables

Source: R/lari.R
lari_tables.Rd

The three output tables of the shared contract.

Usage

lari_tables(m, erase = c("outer", "holes", "hull"))

lari_vertices(m)

lari_triangles(m, erase = c("outer", "holes", "hull"))

lari_segments(m)

lari_edge_sources(m)

lari_depth(m, erase = c("outer", "holes", "hull"))

Arguments

m

a mesh from lari_new()

erase

which triangles to return: "outer" (depth > 0, what Triangle's -p keeps), "holes" (odd depth), "hull" (all). With no segments every triangle is returned.

Value

a data frame; lari_tables() returns the three tables, edge_sources and the report in a list, lari_depth() the depth column of the triangles

Details

  • vertices: x, y, the attribute columns, origin ("input", "crossing", "steiner") and the stable vertex id

  • triangles: v0, v1, v2 (1-based rows of the vertices table), depth and depth_distinct

  • segments: constraint edges v0, v1 (rows of the vertices table), the input segment id they came from (the lowest, when several coincide) and count, the number of input segments covering the edge

  • edge_sources (mesh spec v0.2): one row per constraint edge and input segment covering it, edge (row of the segments table), segment (the input segment id) and forward (TRUE when the input segment runs from the edge's v0 to its v1), sorted by edge then segment. Every covering segment has its own row, through crossings, coincident and collinear overlaps and refinement, so count is the number of rows per edge and segment the lowest of them.

depth is the constraint layer: the number of constraint crossings on the way in from outside the convex hull, counting an edge covered by k input segments k times. depth_distinct is the same count but a doubled boundary (an edge covered by several coincident segments) is crossed once, so it ignores the count weighting. For nested rings odd is inside and even is a hole; for a coverage it orders regions by distance from the boundary.

lari_tables() also returns a one-row report data frame recording the provenance of the tables: backend ("laridae"), the laridae package and cgal versions, the erase region, whether the mesh was refined, the min_edge_length floor, and the last refinement's unrefined counts (bad, short_edge, sharp_corner, outside, inserted, budget_hit, stalled), all NA when the mesh has not been refined.

Row indices are only valid for one snapshot of the tables: use id to follow vertices across edits.

Examples

m <- lari_new(c(0, 1, 1, 0, 0.25, 0.75, 0.75, 0.25),
              c(0, 0, 1, 1, 0.25, 0.25, 0.75, 0.75),
              1:8, c(2, 3, 4, 1, 6, 7, 8, 5))
table(lari_depth(m))
#> 
#> 1 2 
#> 8 2 
lari_segments(m)
#>   v0 v1 segment count
#> 1  1  4       4     1
#> 2  5  8       8     1
#> 3  3  4       3     1
#> 4  1  2       1     1
#> 5  7  8       7     1
#> 6  5  6       5     1
#> 7  2  3       2     1
#> 8  6  7       6     1
lari_edge_sources(m)
#>   edge segment forward
#> 1    1       4   FALSE
#> 2    2       8   FALSE
#> 3    3       3    TRUE
#> 4    4       1    TRUE
#> 5    5       7    TRUE
#> 6    6       5    TRUE
#> 7    7       2    TRUE
#> 8    8       6    TRUE