TRIANGULATION_PLOT
EPS Plots of
Node Triangulations

TRIANGULATION_PLOT is a MATLAB program, using double precision arithmetic, 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.

Related Data and Programs:

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

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

TABLE_DELAUNAY is an executable FORTRAN90 program that can construct the triangulation data for a given node file.

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

TRIANGULATION is a MATLAB library of routines useful for working with triangulations.

TRIANGULATION_DISPLAY_OPEN_GL is an executable C++ program which reads files defining a triangulation and displays an image using Open GL.

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

TRIANGULATION_ORDER3 describes the node and triangle files used for an order 3 triangulation.

TRIANGULATION_ORDER6 describes the node and triangle files used for an order 6 triangulation.

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

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

TRIANGULATION_REFINE is an executable MATLAB program that 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 is an executable MATLAB program that reads data defining a triangulation, determines the neighboring triangles of each triangle, and writes that information to a file.

Usage:

triangulation_plot

The program will prompt you for the values of node_file, triangle_file, node_show and triangle_show.

triangulation_plot node_file triangle_file node_show triangle_show

node_file contains node coordinates;
triangle_file contains node indices that form triangles;
node_show is 0, 1, or 2, to control node visibility;
triangle_show is 0, 1 or 2 to control triangle visibility.

Reference:

1. Marc deBerg, Marc Krevald, Mark Overmars, Otfried Schwarzkopf,
   Computational Geometry,
   Springer, 2000,
   ISBN: 3-540-65620-0.
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.
• dtable_data_read.m reads data from a double precision table file.
• dtable_header_read.m reads the header from a double precision table file.
• file_column_count.m counts the number of columns in the first line of a file.
• file_name_ext_swap.m replaces the current "extension" of a file name.
• file_row_count.m counts the number of row records in a file.
• i4mat_transpose_print_some.m prints some of the transpose of an I4MAT.
• itable_data_read.m reads data from an integer table file.
• itable_header_read.m reads the header from an integer table file.
• r8mat_transpose_print_some.m prints some of the transpose of an R8MAT.
• s_len_trim.m returns the length of a string to the last nonblank.
• s_word_count.m counts the number of "words" in a string.
• timestamp.m prints the current YMDHMS date as a time stamp.
• timestring.m writes the current YMDHMS date into a string.
• triangulation_order3_plot.m plots a 3-node triangulation of a pointset.
• triangulation_order6_plot.m plots a 6-node triangulation of a pointset.

Examples and Tests:

ELL is a set of nodes in an L-shaped region.

• ell_nodes.txt, the nodes.
• ell_triangles3.txt, an order3 triangulation.
• ell_triangles3.png, a PNG image of the order3 triangulation.
• ell_triangles6.txt, an order6 triangulation.
• ell_triangles6.png, a PNG image of the order3 triangulation.

HEX_CVT puts a set of nodes into the double hexagonal hole region using CVT techniques.

• hex_cvt_nodes.txt, the nodes.
• hex_cvt_triangles3.txt, an order3 triangulation, computed by TABLE_DELAUNAY.
• hex_cvt_triangles3.png, a PNG image of the triangulation.

HEX_JEFF puts a set of nodes into the double hexagonal hole region, using an advancing front technique, and organizes them into 6-node triangles.

• hex_jeff_nodes.txt, the nodes;
• hex_jeff_triangles6.txt, an order 6 triangulation, computed by MATLAB.
• hex_jeff_triangles6.png, a PNG image of the triangulation.

HEX_TRIANGLE puts a set of nodes into the double hexagonal hole region using the TRIANGLE program.

• hex_triangle_nodes.txt, the nodes
• hex_triangle_triangles3.txt, an order 3 triangulation, computed by TRIANGLE.
• hex_triangle_angles3.png, a PNG image of the triangulation.

P14_CVT uses constrained CVT methods to place nodes inside and on the boundary of the problem 14 triangulation region, a lake with an island.

• p14_cvt_nodes.txt, the nodes;
• p14_cvt_triangles3.txt, the order 3 triangulation;
• p14_cvt_triangles3.png, a PNG image of the triangulation.

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