openGJK/examples/c/main.c

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  *
 *                                   #####        # #    #                *
 *       ####  #####  ###### #    # #     #       # #   #                 *
 *      #    # #    # #      ##   # #             # #  #                  *
 *      #    # #    # #####  # #  # #  ####       # ###                   *
 *      #    # #####  #      #  # # #     # #     # #  #                  *
 *      #    # #      #      #   ## #     # #     # #   #                 *
 *       ####  #      ###### #    #  #####   #####  #    #                *
 *                                                                        *
 *  This file is part of openGJK.                                         *
 *                                                                        *
 *  openGJK is free software: you can redistribute it and/or modify       *
 *   it under the terms of the GNU General Public License as published by *
 *   the Free Software Foundation, either version 3 of the License, or    *
 *   any later version.                                                   *
 *                                                                        *
 *   openGJK is distributed in the hope that it will be useful,           *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of       *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See The        *
 *   GNU General Public License for more details.                         *
 *                                                                        *
 *  You should have received a copy of the GNU General Public License     *
 *   along with Foobar.  If not, see <https://www.gnu.org/licenses/>.     *
 *                                                                        *
 *       openGJK: open-source Gilbert-Johnson-Keerthi algorithm           *
 *            Copyright (C) Mattia Montanari 2018 - 2019                  *
 *              http://iel.eng.ox.ac.uk/?page_id=504                      *
 *                                                                        *
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  *
 *                                                                        *
 *  This file runs an example to illustrate how to invoke the openGJK lib *
 *   within a C program. An executable called 'demo' can be compiled with *
 *   CMake. This reads the coordinates of two polytopes from the input    *
 *   files userP.dat and userQ.dat, respectively, and returns the minimum *
 *   distance between them computed using the openGJK library.            *
 *                                                                        *
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

 /**
  * @file main.c
  * @author Mattia Montanari
  * @date April 2018
  * @brief File illustrating an application that invokes openGJK.
  *
  */

#define _CRT_HAS_CXX17 0
#include <stdlib.h>
#include <stdio.h>

  /* For importing openGJK this is Step 1: include header in subfolder. */
#include "openGJK/openGJK.h"

#ifndef WIN32
#define fscanf_s fscanf
#endif

/**
* @brief Function for reading input file with body's coordinates.
*
*/
int readinput(const char *inputfile, double ***pts, int * out) {
  int npoints = 0;
  int idx = 0;
  FILE *fp;

  /* Open file. */
#ifdef WIN32
  errno_t err;
  if ((err = fopen_s(&fp, inputfile, "r")) != 0) {
#else
  if ((fp = fopen(inputfile, "r")) == NULL) {
#endif
    fprintf(stdout, "ERROR: input file %s not found!\n", inputfile);
    fprintf(stdout, "  -> The file must be in the folder from which this program is launched\n\n");
    return 1;
  }

  /* Read number of input vertices. */
  if (fscanf(fp, "%d", &npoints) != 1)
    return 1;

  /* Allocate memory. */
  double **arr = (double **)malloc(npoints * sizeof(double *));
  for (int i = 0; i < npoints; i++)
    arr[i] = (double *)malloc(3 * sizeof(double));

  /* Read and store vertices' coordinates. */
  for (idx = 0; idx < npoints; idx++)
  {
    if (fscanf(fp, "%lf %lf %lf\n", &arr[idx][0], &arr[idx][1], &arr[idx][2]) != 3)
      return 1;
  }

  /* Close file. */
  fclose(fp);

  /* Pass pointers. */
  *pts = arr;
  *out = idx;

  return (0);
}


/**
* @brief Main program of example1_c (described in Section 3.1 of the paper).
*
*/
int main() {
  /* Squared distance computed by openGJK.                                 */
  double dd;
  /* Structure of simplex used by openGJK.                                 */
  struct simplex  s;
  /* Number of vertices defining body 1 and body 2, respectively.          */
  int    nvrtx1,
    nvrtx2;
  /* Structures of body 1 and body 2, respectively.                        */
  struct bd       bd1;
  struct bd       bd2;
  /* Specify name of input files for body 1 and body 2, respectively.      */
  char   inputfileA[40] = "userP.dat",
    inputfileB[40] = "userQ.dat";
  /* Pointers to vertices' coordinates of body 1 and body 2, respectively. */
  double(**vrtx1) = NULL,
    (**vrtx2) = NULL;

  /* For importing openGJK this is Step 2: adapt the data structure for the
   * two bodies that will be passed to the GJK procedure. */

   /* Import coordinates of object 1. */
  if (readinput(inputfileA, &vrtx1, &nvrtx1))
    return (1);
  bd1.coord = vrtx1;
  bd1.numpoints = nvrtx1;

  /* Import coordinates of object 2. */
  if (readinput(inputfileB, &vrtx2, &nvrtx2))
    return (1);
  bd2.coord = vrtx2;
  bd2.numpoints = nvrtx2;

  /* Initialise simplex as empty */
  s.nvrtx = 0;

#ifdef DEBUG
  /* Verify input of body A. */
  for (int i = 0; i < bd1.numpoints; ++i) {
    printf("%.2f ", vrtx1[i][0]);
    printf("%.2f ", vrtx1[i][1]);
    printf("%.2f\n", bd1.coord[i][2]);
  }

  /* Verify input of body B. */
  for (int i = 0; i < bd2.numpoints; ++i) {
    printf("%.2f ", bd2.coord[i][0]);
    printf("%.2f ", bd2.coord[i][1]);
    printf("%.2f\n", bd2.coord[i][2]);
  }
#endif

  /* For importing openGJK this is Step 3: invoke the GJK procedure. */
  /* Compute squared distance using GJK algorithm. */
  dd = gjk(bd1, bd2, &s);

  /* Print distance between objects. */
  printf("Distance between bodies %f\n", dd);

  /* Free memory */
  for (int i = 0; i < bd1.numpoints; i++)
    free(bd1.coord[i]);
  free(bd1.coord);
  for (int i = 0; i < bd2.numpoints; i++)
    free(bd2.coord[i]);
  free(bd2.coord);

  return (0);
}