예제 #1
0
/**
 *  intersects a line with the polygon and gives back the two intersection points
 *  @return        TRUE if two intersection can be found, else FALSE
 *  @param x, y     intersection points
 *  @param a, b     define the line to intersection
 */
static bool get_two_intersects(struct FloatVect2 *x, struct FloatVect2 *y, struct FloatVect2 a, struct FloatVect2 b)
{
    int i, count = 0;
    struct FloatVect2 tmp;

    for (i = 0; i < survey.poly_count - 1; i++)
        if (intercept_two_lines(&tmp, a, b, waypoints[survey.poly_first + i].x, waypoints[survey.poly_first + i].y,
                                waypoints[survey.poly_first + i + 1].x, waypoints[survey.poly_first + i + 1].y)) {
            if (count == 0) {
                *x = tmp;
                count++;
            } else {
                *y = tmp;
                count++;
                break;
            }
        }

    //wrapover first,last polygon waypoint
    if (count == 1
            && intercept_two_lines(&tmp, a, b, waypoints[survey.poly_first + survey.poly_count - 1].x,
                                   waypoints[survey.poly_first + survey.poly_count - 1].y, waypoints[survey.poly_first].x,
                                   waypoints[survey.poly_first].y)) {
        *y = tmp;
        count++;
    }

    if (count != 2) {
        return false;
    }

    //change points
    if (fabs(survey.dir_vec.x) > fabs(survey.dir_vec.y)) {
        if ((y->x - x->x) / survey.dir_vec.x < 0.0) {
            tmp = *x;
            *x = *y;
            *y = tmp;
        }
    } else if ((y->y - x->y) / survey.dir_vec.y < 0.0) {
        tmp = *x;
        *x = *y;
        *y = tmp;
    }

    return true;
}
예제 #2
0
/**
   intersects a line with the polygon and gives back the two intersection points
   returns : TRUE if two intersection can be found, else FALSE
   x, y    : intersection points
   a, b    : define the line to intersection
**/
static bool_t get_two_intersects(point2d *x, point2d *y, point2d a, point2d b)
{
  int i, count = 0;
  point2d tmp;

  for (i=0;i<poly_count-1;i++)
    if(intercept_two_lines(&tmp,a,b,waypoints[poly_first+i].x,waypoints[poly_first+i].y,waypoints[poly_first+i+1].x,waypoints[poly_first+i+1].y)) {
      if (count == 0) {
        *x = tmp;
        count++;
      }
      else {
        *y = tmp;
        count++;
        break;
      }
    }

  //wrapover first,last polygon waypoint
  if (count == 1 && intercept_two_lines(&tmp,a,b,waypoints[poly_first+poly_count-1].x,waypoints[poly_first+poly_count-1].y,waypoints[poly_first].x,waypoints[poly_first].y)) {
    *y = tmp;
    count++;
  }

  if (count != 2)
    return FALSE;

  //change points
  if (fabs(dir_vec.x) > fabs(dir_vec.y)) {
    if ((y->x - x->x) / dir_vec.x < 0.0){
      tmp = *x;
      *x = *y;
      *y = tmp;
    }
  }
  else
    if ((y->y - x->y) / dir_vec.y < 0.0) {
      tmp = *x;
      *x = *y;
      *y = tmp;
    }

  return TRUE;
}