Octave has the functions `triplot`

, `trimesh`

, and `trisurf`

to plot the Delaunay triangulation of a 2-dimensional set of points.
`tetramesh`

will plot the triangulation of a 3-dimensional set of points.

- Function File:
**triplot***(*`tri`,`x`,`y`) - Function File:
**triplot***(*`tri`,`x`,`y`,`linespec`) - Function File:
`h`=**triplot***(…)* Plot a 2-D triangular mesh.

`tri`is typically the output of a Delaunay triangulation over the grid of`x`,`y`. Every row of`tri`represents one triangle and contains three indices into [`x`,`y`] which are the vertices of the triangles in the x-y plane.The linestyle to use for the plot can be defined with the argument

`linespec`of the same format as the`plot`

command.The optional return value

`h`is a graphics handle to the created patch object.

- Function File:
**trimesh***(*`tri`,`x`,`y`,`z`,`c`) - Function File:
**trimesh***(*`tri`,`x`,`y`,`z`) - Function File:
**trimesh***(*`tri`,`x`,`y`) - Function File:
**trimesh***(…,*`prop`,`val`, …) - Function File:
`h`=**trimesh***(…)* Plot a 3-D triangular wireframe mesh.

In contrast to

`mesh`

, which plots a mesh using rectangles,`trimesh`

plots the mesh using triangles.`tri`is typically the output of a Delaunay triangulation over the grid of`x`,`y`. Every row of`tri`represents one triangle and contains three indices into [`x`,`y`] which are the vertices of the triangles in the x-y plane.`z`determines the height above the plane of each vertex. If no`z`input is given then the triangles are plotted as a 2-D figure.The color of the trimesh is computed by linearly scaling the

`z`values to fit the range of the current colormap. Use`caxis`

and/or change the colormap to control the appearance.Optionally, the color of the mesh can be specified independently of

`z`by supplying a color matrix,`c`. If`z`has N elements, then`c`should be an Nx1 vector for colormap data or an Nx3 matrix for RGB data.Any property/value pairs are passed directly to the underlying patch object.

The optional return value

`h`is a graphics handle to the created patch object.**See also:**mesh, tetramesh, triplot, trisurf, delaunay, patch, hidden.

- Function File:
**trisurf***(*`tri`,`x`,`y`,`z`,`c`) - Function File:
**trisurf***(*`tri`,`x`,`y`,`z`) - Function File:
**trisurf***(…,*`prop`,`val`, …) - Function File:
`h`=**trisurf***(…)* Plot a 3-D triangular surface.

In contrast to

`surf`

, which plots a surface mesh using rectangles,`trisurf`

plots the mesh using triangles.`tri`is typically the output of a Delaunay triangulation over the grid of`x`,`y`. Every row of`tri`represents one triangle and contains three indices into [`x`,`y`] which are the vertices of the triangles in the x-y plane.`z`determines the height above the plane of each vertex.The color of the trimesh is computed by linearly scaling the

`z`values to fit the range of the current colormap. Use`caxis`

and/or change the colormap to control the appearance.Optionally, the color of the mesh can be specified independently of

`z`by supplying a color matrix,`c`. If`z`has N elements, then`c`should be an Nx1 vector for colormap data or an Nx3 matrix for RGB data.Any property/value pairs are passed directly to the underlying patch object.

The optional return value

`h`is a graphics handle to the created patch object.

- Function File:
**tetramesh***(*`T`,`X`) - Function File:
**tetramesh***(*`T`,`X`,`C`) - Function File:
**tetramesh***(…,*`property`,`val`, …) - Function File:
`h`=**tetramesh***(…)* Display the tetrahedrons defined in the m-by-4 matrix

`T`as 3-D patches.`T`is typically the output of a Delaunay triangulation of a 3-D set of points. Every row of`T`contains four indices into the n-by-3 matrix`X`of the vertices of a tetrahedron. Every row in`X`represents one point in 3-D space.The vector

`C`specifies the color of each tetrahedron as an index into the current colormap. The default value is 1:m where m is the number of tetrahedrons; the indices are scaled to map to the full range of the colormap. If there are more tetrahedrons than colors in the colormap then the values in`C`are cyclically repeated.Calling

`tetramesh (…, "property", "value", …)`

passes all property/value pairs directly to the patch function as additional arguments.The optional return value

`h`is a vector of patch handles where each handle represents one tetrahedron in the order given by`T`. A typical use case for`h`is to turn the respective patch`"visible"`

property`"on"`

or`"off"`

.Type

`demo tetramesh`

to see examples on using`tetramesh`

.

The difference between `triplot`

, and `trimesh`

or `triplot`

,
is that the former only plots the 2-dimensional triangulation itself, whereas
the second two plot the value of a function `f (`

. An
example of the use of the `x`, `y`)`triplot`

function is

rand ("state", 2) x = rand (20, 1); y = rand (20, 1); tri = delaunay (x, y); triplot (tri, x, y);

which plots the Delaunay triangulation of a set of random points in 2-dimensions. The output of the above can be seen in Figure 30.2.