Description Usage Arguments Value Author(s) References See Also Examples
This function extracts a triangulation data structure
from an triangulation object created by tri.mesh
.
The vertices in the returned matrix (let's denote it with
retval
) are ordered
counterclockwise with the first vertex taken
to be the one with smallest index. Thus,
retval[i,"node2"]
and retval[i,"node3"]
are larger
than
retval[i,"node3"]
and index adjacent neighbors of
node retval[i,"node1"]
. The columns trx
and
arcx
, x=1,2,3 index the triangle and arc,
respectively, which are opposite (not shared
by) node nodex
, with trix
= 0 if
arcx
indexes a boundary arc. Vertex
indexes range from 1 to N, triangle indexes
from 0 to NT, and, if included, arc indexes
from 1 to NA = NT+N-1. The triangles are
ordered on first (smallest) vertex indexes,
except that the sets of constraint triangles
(triangles contained in the closure of a constraint
region) follow the non-constraint
triangles.
1 | triangles(tri.obj)
|
tri.obj |
object of class |
A matrix with columns node1
,node2
,node3
,
representing the vertex nodal indexes,
tr1
,tr2
,tr3
, representing neighboring triangle
indexes and arc1
,arc2
,arc3
reresenting arc indexes.
Each row represents one triangle.
A. Gebhardt
R. J. Renka (1996). Algorithm 751: TRIPACK: a constrained two-dimensional Delaunay triangulation package. ACM Transactions on Mathematical Software. 22, 1-8.
tri
, print.tri
, plot.tri
, summary.tri
, triangles
1 2 3 4 |
node1 node2 node3 tr1 tr2 tr3 arc1 arc2 arc3
[1,] 1 2 3 6 2 0 7 2 1
[2,] 1 3 4 8 3 1 10 4 2
[3,] 1 4 7 9 0 2 12 3 4
[4,] 2 8 5 11 5 0 15 6 5
[5,] 2 5 10 12 6 4 16 8 6
[6,] 2 10 3 7 1 5 9 7 8
[7,] 3 10 9 17 8 6 26 11 9
[8,] 3 9 4 10 2 7 14 10 11
[9,] 4 12 7 14 3 10 19 12 13
[10,] 4 9 12 18 9 8 28 13 14
[11,] 5 8 11 16 12 4 22 17 15
[12,] 5 11 10 17 5 11 25 16 17
[13,] 6 8 7 0 14 16 18 20 23
[14,] 6 7 12 9 15 13 19 21 20
[15,] 6 12 11 18 16 14 27 24 21
[16,] 6 11 8 11 13 15 22 23 24
[17,] 9 10 11 12 18 7 25 29 26
[18,] 9 11 12 15 10 17 27 28 29
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