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/****** path_finder.c ***********************************************
This recursive function traces the least cost path backwards
to cells from which the cumulative cost was determined
*********************************************************************/
#include <grass/segment.h>
#include "local_proto.h"
void path_finder(int row, int col, int backrow, int backcol)
{
int data, new_backrow, new_backcol;
extern char *value;
extern int nrows, ncols;
extern SEGMENT in_row_seg, in_col_seg, out_seg;
if (row < 0 || row >= nrows || col < 0 || col >= ncols)
return; /* outside the window */
/* if the pt has already been traversed, return */
value = (char *)&data;
Segment_get(&out_seg, value, row, col);
if (data == 1)
return; /* already traversed */
/* otherwise, draw a line on output */
drawline(row, col, backrow, backcol);
/*DEBUG
printf("\nrow=%d, col=%d, backrow=%d, backcol=%d", row, col, backrow,
backcol);
*/
/* update path position */
if (row == backrow && col == backcol) {
printf("\n");
return;
} /* reach an origin */
value = (char *)&new_backrow;
Segment_get(&in_row_seg, value, backrow, backcol);
value = (char *)&new_backcol;
Segment_get(&in_col_seg, value, backrow, backcol);
path_finder(backrow, backcol, new_backrow, new_backcol);
return;
}
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