# vertexAttachments

Class: TriRep

(Will be removed) Return simplices attached to specified vertices

 Note:   `vertexAttachments(TriRep)` will be removed in a future release. Use `vertexAttachments(triangulation)` instead.`TriRep` will be removed in a future release. Use `triangulation` instead.

## Syntax

` SI = vertexAttachments(TR, VI)`

## Description

` SI = vertexAttachments(TR, VI)` returns the vertex-to-simplex information for the specified vertices `VI`. For 2-D triangulations in MATLAB®, the triangles `SI` are arranged in counter-clockwise order around the attached vertex `VI`.

## Input Arguments

 `TR` Triangulation representation `VI` `VI` is a column vector of indices into the array of points representing the vertex coordinates, `TR.X`. The simplices associated with vertex `i` are the `i`'th entry in the cell array. If `VI` is not specified the vertex-simplex information for the entire triangulation is returned.

## Output Arguments

 `SI` Cell array of indices of the simplices attached to a vertex. A cell array is used to store the information because the number of simplices associated with each vertex can vary. The simplices associated with vertex `i` are in the `i`'th entry in the cell array `SI`.

## Definitions

A simplex is a triangle/tetrahedron or higher dimensional equivalent.

## Examples

### Example 1

Load a 2-D triangulation and use `TriRep` to compute the vertex-to-triangle relations.

```load trimesh2d trep = TriRep(tri, x, y);```
Find the indices of the tetrahedra attached to the first vertex:
```Tv = vertexAttachments(trep, 1) Tv{:}```

### Example 2

Perform a direct query of a 2-D triangulation created using `DelaunayTri`.

```x = rand(20,1); y = rand(20,1); dt = DelaunayTri(x,y);```
Find the triangles attached to vertex 5:
`t = vertexAttachments(dt,5);`
Plot the triangulation:
```triplot(dt); hold on;```
Plot the triangles attached to vertex 5 (in red):
```triplot(dt(t{:},:),x,y,'Color','r'); hold off;```