TRIANGULATION_DISPLAY_OPEN_GL
Display a Triangulation Using OpenGL

TRIANGULATION_DISPLAY_OPEN_GL is an executable C++ program, using single precision arithmetic, that reads the name of two data files defining a triangulation, reads the data, and displays the triangulation using OPEN_GL.

The files defining the triangulation consist of one file containing the coordinates of the points, and a second file that lists the indices of the nodes making up each triangle. Either 3-node or 6-node triangles may be used.

Usage:

triangulation_display_open_gl nodes.txt triangles.txt

reads the node data from nodes.txt, the triangle data from triangles.txt and displays a plot 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.

FLOOD_OPEN_GL is a C program which allows a user to select a region and flood it with color, using OpenGL, by Art Wetzel.

OPEN_GL is used to handle the graphics display.

TABLE is a format used for the input files to TRIANGULATION_DISPLAY_OPEN_GL.

TABLE_DELAUNAY is an executable C++ program which computes the Delaunay triangulation of a set of points.

TABLE_IO is a C++ library which supplies the routines used to read the TABLE file.

TABLE_VORONOI is an executable C++ program which can be used to compute information about the Voronoi diagram of the points.

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

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

TRIANGULATION_ORDER3 is a directory which contains a description and examples of order 3 triangulations.

TRIANGULATION_ORDER6 is a directory which contains a description and examples of order 6 triangulations.

TRIANGULATION_PLOT is an executable C++ program that reads data defining a triangulation and creates a PostScript image of the nodes and triangles.

Reference:

1. Edward Angel,
   Interactive Computer Graphics,
   A Top-Down Approach with OpenGL,
   Addison-Wesley, 2000,
   LC: T385.A514.
2. Renate Kempf, Chris Frazier, editors,
   OpenGL Reference Manual,
   Addison-Wesley, 1997,
   LC: T385.O642.
3. Mason Woo, Jackie Neider, Tom Davis,
   OpenGL Programming Guide,
   Addison-Wesley, 1997,
   LC: T385.N435.
4. Richard Wright, Michael Sweet,
   OpenGL Superbible,
   Waite Group Press, 1996,
   LC: T385.W73.
5. http://www.opengl.org/
   The official OpenGL site.

Source Code:

• triangulation_display_open_gl.C, the source code.
• triangulation_display_open_gl.csh, commands to compile the source code.

Examples and Tests:

ELL is an L-shaped region, which may be triangulated by order-3 triangles.

• ell_tri3.out, the printed output in response to the command:

  
              triangulation_display_open_gl ell_nodes.txt ell_tri3.txt

• ell_nodes.txt, 21 nodes in an L-shaped region.
• ell_tri3.txt, an order-3 triangulation of the nodes.
• ell_tri3.png, a PNG image of the triangulation.

ELL is an L-shaped region, which may be triangulated by order-6 triangles.

• ell_tri6.out, the printed output in response to the command:

  
              triangulation_display_open_gl ell_nodes.txt ell_tri6.txt

• ell_nodes.txt, 21 nodes in an L-shaped region.
• ell_tri6.txt, an order-6 triangulation of the nodes.
• ell_tri6.png, a PNG image of the triangulation.

List of Routines:

• MAIN is the main program for TRIANGULATION_DISPLAY_OPEN_GL.
• CH_EQI is true if two characters are equal, disregarding case.
• CH_TO_DIGIT returns the integer value of a base 10 digit.
• DISPLAY generates the graphics output.
• DTABLE_DATA_READ reads the data from a real TABLE file.
• DTABLE_HEADER_READ reads the header from a real TABLE file.
• FILE_COLUMN_COUNT counts the number of columns in the first line of a file.
• FILE_ROW_COUNT counts the number of row records in a file.
• I4_MAX returns the maximum of two I4's.
• I4_MIN returns the smaller of two I4's.
• I43MAT_FLIP_COLS swaps the columns of an I43MAT.
• ITABLE_DATA_READ reads data from an integer TABLE file.
• ITABLE_HEADER_READ reads the header from an integer TABLE file.
• MYINIT initializes OpenGL state variables dealing with viewing and attributes.
• PPMA_WRITE writes the header and data for an ASCII portable pixel map file.
• PPMA_WRITE_DATA writes the data for an ASCII portable pixel map file.
• PPMA_WRITE_HEADER writes the header of an ASCII portable pixel map file.
• R8_MAX returns the maximum of two R8's.
• R82VEC_MAX returns the maximum value in an R82VEC.
• R82VEC_MIN returns the minimum value in an R82VEC.
• S_LEN_TRIM returns the length of a string to the last nonblank.
• S_TO_I4 reads an I4 from a string.
• S_TO_I4VEC reads an I4VEC from a string.
• S_TO_R8 reads an R8 from a string.
• S_TO_R8VEC reads an R8VEC from a string.
• S_WORD_COUNT counts the number of "words" in a string.
• TIMESTAMP prints the current YMDHMS date as a time stamp.
• TIMESTRING returns the current YMDHMS date as a string.

You can go up one level to the C++ source codes.