TRIANGULATION_PLOT
Plot a Triangulation

TRIANGULATION_PLOT is a MATLAB program which plots a triangulation.

TRIANGULATION_PLOT reads one file listing the nodes, and a second file consisting of groups of 3 or 6 nodes that make up triangles, and creates an Encapsulated PostScript image of the triangulation.

Usage:

triangulation_plot ( 'prefix', node_vis, triangle_vis )

• 'prefix'_nodes.txt, the node coordinates.
• 'prefix'_elements.txt, the triangulation
• 'prefix'.eps, the plot file

• 0, do not show the nodes;
• 1, show the nodes;
• 2, show the nodes and label them.

• 0, do not show the triangles;
• 1, show the triangles;
• 2, show the triangles and label them.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

TRIANGULATION_PLOT is available in a C++ version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

FEM_BASIS_T3_DISPLAY, a MATLAB program which displays a basis function associated with a linear triangle ("T3") mesh.

FEM_BASIS_T6_DISPLAY, a MATLAB program which reads a quadratic triangle mesh and displays any associated basis function.

TABLE_DELAUNAY, a FORTRAN90 program which can construct the triangulation data for a given node file.

TRI_SURFACE_DISPLAY, a MATLAB program which reads data defining a triangular mesh of a 3D surface and displays it.

TRIANGULATION, a MATLAB library which is useful for working with triangulations.

TRIANGULATION_CORNER, a MATLAB program which patches triangulations so that no triangle has two sides on the boundary.

TRIANGULATION_DELAUNAY_DISCREPANCY, a MATLAB program which measures the amount by which a triangulation fails the local Delaunay test;

TRIANGULATION_DISPLAY, a MATLAB program which displays the nodes and elements of a triangulation on the MATLAB graphics screen;

TRIANGULATION_DISPLAY_OPENGL, a C++ program which reads files defining a triangulation and displays an image using Open GL.

TRIANGULATION_HISTOGRAM, a MATLAB program which computes histograms of data over a triangulation.

TRIANGULATION_MASK, a MATLAB program which takes an existing triangulation and deletes triangles and their corresponding nodes as requested by the user.

TRIANGULATION_ORDER3, a data directory which describes the node and triangle files used for an order 3 triangulation.

TRIANGULATION_ORDER6, a data directory which describes the node and triangle files used for an order 6 triangulation.

TRIANGULATION_ORIENT, a MATLAB program which reads data defining a triangulation, makes sure that every triangle has positive orientation, and if not, writes a corrected triangle file.

TRIANGULATION_QUAD, a MATLAB program which estimates the integral of a function over a triangulated region.

TRIANGULATION_REFINE, a MATLAB program which reads data defining a triangulation, replaces each triangle by four congruent smaller ones, and writes the new triangulation information to a file.

TRIANGULATION_TRIANGLE_NEIGHBORS, a MATLAB program which reads data defining a triangulation, determines the neighboring triangles of each triangle, and writes that information to a file.

Reference:

1. Marc deBerg, Marc Krevald, Mark Overmars, Otfried Schwarzkopf,
   Computational Geometry,
   Springer, 2000,
   ISBN: 3-540-65620-0,
   LC: QA448.D38.C65.
2. Joseph ORourke,
   Computational Geometry,
   Second Edition,
   Cambridge, 1998,
   ISBN: 0521649765,
   LC: QA448.D38.

Source Code:

• triangulation_plot.m plots a triangulated set of nodes.

Examples and Tests:

ELBOW3 is an elbow-shaped region, triangulated using order 3 triangles.

• elbow3_nodes.txt the point coordinates.
• elbow3_elements.txt the triangulation.
• elbow3_triangulation.png is a PNG image of the triangulation.

ELL3 is an order 3 triangulation of a set of nodes in an L-shaped region.

• ell3_nodes.txt, the nodes.
• ell3_elements.txt, the triangulation.
• ell3_triangulation.png, a PNG image of the triangulation.

ELL6 is an order 6 triangulation of a set of nodes in an L-shaped region.

• ell6_nodes.txt, the nodes.
• ell6_elements.txt, the triangulation.
• ell6_triangulation.png, a PNG image of the triangulation.

HEX_HOLES3 puts a set of nodes into the double hexagonal hole region using CVT techniques, and creates an order 3 triangulation using TABLE_DELAUNAY.

• hex_holes3_nodes.txt, the nodes.
• hex_holes3_elements.txt, the triangulation.
• hex_holes3_triangulation.png, a PNG image of the triangulation.

LAKE3 uses constrained CVT methods to place nodes inside and on the boundary of the problem 14 triangulation region, a lake with an island. An order 3 triangulation is used.

• lake3_nodes.txt, the nodes;
• lake3_elements.txt, the triangles;
• lake3_triangulation.png, a PNG image of the triangulation.

You can go up one level to the MATLAB source codes.