/* Badouel / Wuthrich "Face Connected Line Segment Generation in an    N-dimensional Space" *//******************************************************************************Data structure for n-dimensional line segment generation. Initialized by the procedure Init() and used by the procedure Incr().******************************************************************************/#define DIM   4                  /* number of dimensions                     */typedef struct {  int  D[DIM];                   /* counter for each of the N dimensions     */  int  N[DIM];                   /* increment for each of the N dimensions   */  int  S[DIM];                   /* orientation for each of the N dimensions */  int  cm;                       /* common multiple                          */} Nline;/******************************************************************************Init(): initializes the data structure in order to generate the discretepath between the point P and the point Q in an n-dimensional space.This procedure should be called once before using Incr().Entry:	P    - origin point        Q    - destination point        line - line segment data structure******************************************************************************/void Init (P, Q, line)     int   *P, *Q;     Nline *line;{  int i, v;  line->cm = 1;  for (i=0; i<DIM; i++) {    v = Q[i] - P[i];    if (v < 0) {      line->S[i] = -1; line->N[i] = -v;    } else {      line->S[i] =  1; line->N[i] =  v;    }    if (line->N[i] != 0) line->cm *= line->N[i];  }  for (i=0; i<DIM; i++) {    if (line->N[i] == 0)       line->D[i] = 2*line->cm;    else {      line->D[i] = line->cm/line->N[i];      line->N[i] = 2*line->D[i];    }  }}/******************************************************************************Incr(): generates one step of a discrete segment line in an n-dimensional space. Indicate the end of the generation with the returned value -1 for the direction.The procedure Init() must be called once before using Incr(). Entry:	line - line segment data structureExit:   d    - current step direction        s    - current step orientation******************************************************************************/int Incr (line, d, s)     Nline *line;     int   *d, *s;{  int i, v = 2*line->cm;  *d = -1;  for (i=0; i<DIM; i++) {    if (line->D[i] < v) {      v = line->D[i];      *d = i;    }  }  line->D[*d] += line->N[*d];  *s = line->S[*d];  return *d;}