TRIANGULATION_DISPLAY_OPENGL
Display a Triangulation Using OpenGL

TRIANGULATION_DISPLAY_OPENGL is a C++ program which reads the name of two data files defining a triangulation, reads the data, and displays the triangulation using OpenGL.

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_opengl prefix

• prefix_nodes.txt contains the node coordinates,
• prefix_elements.txt contains the element definitions.

Licensing:

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

Languages:

TRIANGULATION_DISPLAY_OPENGL is available in a C++ version.

Related Data and Programs:

CAUSTIC_OPENGL, a C++ program which computes a caustic curve and displays it using OpenGL.

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.

FERN_OPENGL, a C++ program which uses OpenGL to display the Barnsley fractal fern.

LIFE_OPENGL, a C++ program which simulates a version of John Conway's "Game of Life", displaying the results using OpenGL.

LIGHTS_OUT_OPENGL, a C++ program which sets up a "Lights Out" game and allows the user to solve it, using the OpenGL graphics window.

LISSAJOUS_OPENGL, a C++ program which computes a Lissajous figure and displays it using OpenGL.

MESH_DISPLAY_OPENGL, a C++ program which reads data defining a polygonal mesh and displays it using OpenGL.

OPENGL, C++ programs which illustrate the use of the OpenGL graphics library;

POLYGONAL_SURFACE_DISPLAY_OPENGL, a C++ program which displays a surface in 3D described as a set of polygons, using OpenGL.

ROTATING_CUBE_DISPLAY_OPENGL, a C++ program which displays a rotating color cube in 3D, using OpenGL;

SCREENSHOT_OPENGL, a C++ program which shows how a program using the OpenGL graphics library can save a screenshot of the graphics being displayed.

SPHERE_XYZ_DISPLAY_OPENGL, a C++ program which reads XYZ information defining points in 3D, and displays a unit sphere and the points, using OpenGL.

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

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

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

TRIANGULATION_NODE_TO_ELEMENT, a C++ program which reads files describing a set of nodes, their triangulation, and the value of one or more quantities at each node, and outputs a file that averages the quantities for each element. This operation in effect creates an "order1" finite element model of the data.

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

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

TRIANGULATION_PLOT, a C++ program which reads data defining a triangulation and creates a PostScript image of the nodes and triangles.

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

XY_DISPLAY_OPENGL, a C++ program which reads an XY file of 2D point coordinates, and displays an image of those points using OpenGL.

XYL_DISPLAY_OPENGL, a C++ program which reads XYL information defining points and lines in 2D, and displays an image using OpenGL.

XYZ_DISPLAY_OPENGL, a C++ program which reads an XYZ file of 3D point coordinates, and displays an image of those points using OpenGL.

Reference:

1. Edward Angel,
   Interactive Computer Graphics, a Top-Down Approach with OpenGL,
   Addison-Wesley, 2000,
   ISBN: 0-201-38597-X,
   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_opengl.cpp, the source code.

Examples and Tests:

ELL3 is an L-shaped region, which may be triangulated by order-3 triangles.

• ell3_output.txt, the printed output in response to the command:

  
              triangulation_display_opengl ell_nodes.txt ell_tri3.txt

• ell3_nodes.txt, 21 nodes in an L-shaped region.
• ell3_elements.txt, an order-3 triangulation of the nodes.
• ell3.png, a PNG image of the triangulation.

ELL6 is an L-shaped region, which may be triangulated by order-6 triangles.

• ell6_output.txt, the printed output in response to the command:

  
              triangulation_display_opengl ell_nodes.txt ell_tri6.txt

• ell6_nodes.txt, 21 nodes in an L-shaped region.
• ell6_elements.txt, an order-6 triangulation of the nodes.
• ell6.png, a PNG image of the triangulation.

List of Routines:

• MAIN is the main program for TRIANGULATION_DISPLAY_OPENGL.
• 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.
• 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.
• I4MAT_DATA_READ reads data from an I4MAT file.
• I4MAT_HEADER_READ reads the header from an I4MAT file.
• MYINIT initializes OpenGL state variables dealing with viewing and attributes.
• R8_MAX returns the maximum of two R8's.
• R82VEC_MAX returns the maximum value in a R82VEC.
• R82VEC_MIN returns the minimum value in a R82VEC.
• R8MAT_DATA_READ reads the data from an R8MAT file.
• R8MAT_HEADER_READ reads the header from an R8MAT file.
• 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.

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