Fast meshing of grid-like ordered vertices

create_faces.c

/*****************************************************************************
 * Fast meshing of grid-like ordered vertices.
 * This code snippet shows the indexing for a faces array to mesh grid-like
 * ordered vertices using only one for loop. The indexing looks as follows:
 *
 *        0-----1-----2-----3
 *        |   //|   //|   //|
 *        |  // |  // |  // |
 *        | //  | //  | //  |
 *        |//   |//   |//   |
 *        4-----5-----6-----7
 *        |   //|   //|   //|
 *        |  // |  // |  // |
 *        | //  | //  | //  |
 *        |//   |//   |//   |
 *        8-----9-----10----11
 *        |   //|   //|   //|
 *        |  // |  // |  // |
 *        | //  | //  | //  |
 *        |//   |//   |//   |
 *        12----13----14----15
 */
#include <stdio.h>

int main() {

    int cols = 4;
    int rows = 4;
    int nmax = (cols*rows)-2;

    for(int n=0; n<cols*(rows-1); n+=1+((n+2)%cols==0)) {
        printf("(%d, %d, %d), (%d, %d, %d)\n", n, n+cols, n+1, nmax-n, 
                                               nmax-n+1, nmax-n-cols+1);
    }

    return 0;
}

Compile with: gcc -std=c99 create_faces.c -o create_faces