HEX_GRID_TRIANGULATE
Select Hex Grid Points in a Region

HEX_GRID_TRIANGULATE is a FORTRAN90 program which picks out those points on a hex grid which lie inside a given triangulation region.

We assume we have the following information available:

• nodes_per_layer, the number of hex grid nodes to be placed on the first horizontal layer of the grid;
• box[2,2], the coordinates of the lower left and upper right corners of a box that bounds the region;
• inside[p], a function which returns TRUE if a point p is inside the region;

Using this information, the program constructs a hexagonal grid of points inside the box, discards all the grid points that don't actually lie inside the region, and writes the remaining points to a file.

Licensing:

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

Languages:

HEX_GRID_TRIANGULATE is available in a FORTRAN90 version.

Related Data and Programs:

HEX_GRID, a FORTRAN90 library which is used to define the underlying hex grids.

HEX_GRID, a dataset directory which contains more examples of hexagonal grids.

HEX_GRID_ANGLE, a FORTRAN90 library which computes elements of an angled hexagonal grid dataset.

TEST_TRIANGULATION, a FORTRAN90 library which contains routines which define the regions to be triangulated.

TRIANGLE_GRID, a FORTRAN90 library which computes a triangular grid of points.

Source Code:

• hex_grid_triangulate.f90, the source code.
• hex_grid_triangulate.sh, commands to compile, link and run the source code.
• hex_grid_triangulate.txt, the output file.

Examples and Tests:

Sample hexagonal grid files you may copy include:

• p_1_40_46_1377.txt
• p_2_40_46_1156.txt
• p_3_40_46_1596.txt
• p_4_40_40_857.txt
• p_5_40_23_489.txt
• p_6_40_46_1212.txt
• p_7_40_18_459.txt
• p_8_40_24_388.txt
• p_9_40_46_1725.txt
• p_10_40_46_1817.txt
• p_11_40_46_1369.txt
• p_12_40_46_1633.txt
• p_13_40_46_279.txt
• p_14_40_56_769.txt

There are PNG images of the data available:

• p_1_40_46_1377.png
• p_2_40_46_1156.png
• p_3_40_46_1596.png
• p_4_40_40_857.png
• p_5_40_23_489.png
• p_6_40_46_1212.png
• p_7_40_18_459.png
• p_8_40_24_388.png
• p_9_40_46_1725.png
• p_10_40_46_1817.png
• p_11_40_46_1369.png
• p_12_40_46_1633.png
• p_13_40_46_279.png
• p_14_40_56_769.png

List of Routines:

• MAIN is the main program for HEX_GRID_TRIANGULATE.
• TEST01 computes a hexagonal grid in an unknown triangulation region.

You can go up one level to the FORTRAN90 source codes.