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mapsearch.c

/******************************************************************************
 *
 * Project:  MapServer
 * Purpose:  Various geospatial search operations.
 * Author:   Steve Lime and the MapServer team.
 *
 ******************************************************************************
 * Copyright (c) 1996-2005 Regents of the University of Minnesota.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in 
 * all copies of this Software or works derived from this Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ******************************************************************************
 *
 * $Log: mapsearch.c,v $
 * Revision 1.17  2005/06/14 16:03:34  dan
 * Updated copyright date to 2005
 *
 * Revision 1.16  2005/02/18 03:06:47  dan
 * Turned all C++ (//) comments into C comments (bug 1238)
 *
 * Revision 1.15  2004/10/21 04:30:54  frank
 * Added standardized headers.  Added MS_CVSID().
 *
 */

#include "map.h"

MS_CVSID("$Id: mapsearch.c,v 1.17 2005/06/14 16:03:34 dan Exp $")

#define LASTVERT(v,n)  ((v) == 0 ? n-2 : v-1)
#define NEXTVERT(v,n)  ((v) == n-2 ? 0 : v+1)

/*
** Returns MS_TRUE if rectangles a and b overlap
*/
int msRectOverlap(rectObj *a, rectObj *b)
{
  if(a->minx > b->maxx) return(MS_FALSE);
  if(a->maxx < b->minx) return(MS_FALSE);
  if(a->miny > b->maxy) return(MS_FALSE);
  if(a->maxy < b->miny) return(MS_FALSE);
  return(MS_TRUE);
}

/*
** Returns MS_TRUE if rectangle a is contained in rectangle b
*/
int msRectContained(rectObj *a, rectObj *b)
{
  if(a->minx >= b->minx && a->maxx <= b->maxx)
    if(a->miny >= b->miny && a->maxy <= b->maxy)
      return(MS_TRUE);
  return(MS_FALSE);  
}

/*
** Merges rect b into rect a. Rect a changes, b does not.
*/
void msMergeRect(rectObj *a, rectObj *b)
{
  a->minx = MS_MIN(a->minx, b->minx);
  a->maxx = MS_MAX(a->maxx, b->maxx);
  a->miny = MS_MIN(a->miny, b->miny);
  a->maxy = MS_MAX(a->maxy, b->maxy);
}

int msPointInRect(pointObj *p, rectObj *rect)
{
  if(p->x < rect->minx) return(MS_FALSE);
  if(p->x > rect->maxx) return(MS_FALSE);
  if(p->y < rect->miny) return(MS_FALSE);
  if(p->y > rect->maxy) return(MS_FALSE);
  return(MS_TRUE);
}

int msPolygonDirection(lineObj *c)
{
  double mx, my, area;
  int i, v=0, lv, nv;

  /* first find lowest, rightmost point of polygon */
  mx = c->point[0].x;
  my = c->point[0].y;

  for(i=0; i<c->numpoints-1; i++) {
    if((c->point[i].y < my) || ((c->point[i].y == my) && (c->point[i].x > mx))) {
      v = i;
      mx = c->point[i].x;
      my = c->point[i].y;
    }
  }

  lv = LASTVERT(v,c->numpoints);
  nv = NEXTVERT(v,c->numpoints);

  area = c->point[lv].x*c->point[v].y - c->point[lv].y*c->point[v].x + c->point[lv].y*c->point[nv].x - c->point[lv].x*c->point[nv].y + c->point[v].x*c->point[nv].y - c->point[nv].x*c->point[v].y;   
  if(area > 0)
    return(1); /* counter clockwise orientation */ 
  else 
    if(area < 0) /* clockwise orientation */
      return(-1);
    else
      return(0); /* shouldn't happen unless the polygon is self intersecting */
}

int msPointInPolygon(pointObj *p, lineObj *c)
{
  int i, j, status = MS_FALSE;

  for (i = 0, j = c->numpoints-1; i < c->numpoints; j = i++) {
    if ((((c->point[i].y<=p->y) && (p->y<c->point[j].y)) || ((c->point[j].y<=p->y) && (p->y<c->point[i].y))) && (p->x < (c->point[j].x - c->point[i].x) * (p->y - c->point[i].y) / (c->point[j].y - c->point[i].y) + c->point[i].x))
      status = !status;
  }
  return status;
}

/*
** Note: the following functions are brute force implementations. Some fancy
** computational geometry algorithms would speed things up nicely in many
** cases. In due time... -SDL-
*/

int msIntersectSegments(pointObj *a, pointObj *b, pointObj *c, pointObj *d) { /* from comp.graphics.alogorithms FAQ */

  double r, s;
  double denominator, numerator;

  numerator = ((a->y-c->y)*(d->x-c->x) - (a->x-c->x)*(d->y-c->y));  
  denominator = ((b->x-a->x)*(d->y-c->y) - (b->y-a->y)*(d->x-c->x));  

  if((denominator == 0) && (numerator == 0)) { /* lines are coincident, intersection is a line segement if it exists */
    if(a->y == c->y) { /* coincident horizontally, check x's */
      if(((a->x >= MS_MIN(c->x,d->x)) && (a->x <= MS_MAX(c->x,d->x))) || ((b->x >= MS_MIN(c->x,d->x)) && (b->x <= MS_MAX(c->x,d->x))))
  return(MS_TRUE);
      else
  return(MS_FALSE);
    } else { /* test for y's will work fine for remaining cases */
      if(((a->y >= MS_MIN(c->y,d->y)) && (a->y <= MS_MAX(c->y,d->y))) || ((b->y >= MS_MIN(c->y,d->y)) && (b->y <= MS_MAX(c->y,d->y))))
  return(MS_TRUE);
      else
  return(MS_FALSE);
    }
  }

  if(denominator == 0) /* lines are parallel, can't intersect */
    return(MS_FALSE);

  r = numerator/denominator;

  if((r<0) || (r>1))
    return(MS_FALSE); /* no intersection */

  numerator = ((a->y-c->y)*(b->x-a->x) - (a->x-c->x)*(b->y-a->y));
  s = numerator/denominator;

  if((s<0) || (s>1))
    return(MS_FALSE); /* no intersection */

  return(MS_TRUE);
}

/*
** Instead of using ring orientation we count the number of parts the
** point falls in. If odd the point is in the polygon, if 0 or even
** then the point is in a hole or completely outside.
*/
int msIntersectPointPolygon(pointObj *point, shapeObj *poly) {
  int i;
  int status=MS_FALSE;

  for(i=0; i<poly->numlines; i++) {
    if(msPointInPolygon(point, &poly->line[i]) == MS_TRUE) /* ok, the point is in a line */
      status = !status;
  }

  return(status);  
}

int msIntersectMultipointPolygon(multipointObj *points, shapeObj *poly) {
  int i;
  
  for(i=0; i<points->numpoints; i++) {
    if(msIntersectPointPolygon(&(points->point[i]), poly) == MS_TRUE)
      return(MS_TRUE);
  }
    
  return(MS_FALSE);
}

int msIntersectPolylines(shapeObj *line1, shapeObj *line2) {
  int c1,v1,c2,v2;

  for(c1=0; c1<line1->numlines; c1++)
    for(v1=1; v1<line1->line[c1].numpoints; v1++)
      for(c2=0; c2<line2->numlines; c2++)
  for(v2=1; v2<line2->line[c2].numpoints; v2++)
    if(msIntersectSegments(&(line1->line[c1].point[v1-1]), &(line1->line[c1].point[v1]), &(line2->line[c2].point[v2-1]), &(line2->line[c2].point[v2])) ==  MS_TRUE)
      return(MS_TRUE);

  return(MS_FALSE);
}

int msIntersectPolylinePolygon(shapeObj *line, shapeObj *poly) {
  int c1,v1,c2,v2;

  /* STEP 1: polygon might competely contain the polyline or one of it's parts (only need to check one point from each part) */
  for(c1=0; c1<line->numlines; c1++) {
    if(msIntersectPointPolygon(&(line->line[c1].point[0]), poly) == MS_TRUE) /* this considers holes and multiple parts */
      return(MS_TRUE);
  }


  /* STEP 2: look for intersecting line segments */
  for(c1=0; c1<line->numlines; c1++)
    for(v1=1; v1<line->line[c1].numpoints; v1++)
      for(c2=0; c2<poly->numlines; c2++)
  for(v2=1; v2<poly->line[c2].numpoints; v2++)
    if(msIntersectSegments(&(line->line[c1].point[v1-1]), &(line->line[c1].point[v1]), &(poly->line[c2].point[v2-1]), &(poly->line[c2].point[v2])) ==  MS_TRUE)
      return(MS_TRUE);
  
  return(MS_FALSE);
}

int msIntersectPolygons(shapeObj *p1, shapeObj *p2) {
  int c1,v1,c2,v2;

  /* STEP 1: polygon 1 completely contains 2 (only need to check one point from each part) */
  for(c2=0; c2<p2->numlines; c2++) {
    if(msIntersectPointPolygon(&(p2->line[c2].point[0]), p1) == MS_TRUE) /* this considers holes and multiple parts */
      return(MS_TRUE);
  }

  /* STEP 2: polygon 2 completely contains 1 (only need to check one point from each part) */
  for(c1=0; c1<p1->numlines; c1++) {
    if(msIntersectPointPolygon(&(p1->line[c1].point[0]), p2) == MS_TRUE) /* this considers holes and multiple parts */
      return(MS_TRUE);
  }

  /* STEP 3: look for intersecting line segments */
  for(c1=0; c1<p1->numlines; c1++)
    for(v1=1; v1<p1->line[c1].numpoints; v1++)
      for(c2=0; c2<p2->numlines; c2++)
  for(v2=1; v2<p2->line[c2].numpoints; v2++)
    if(msIntersectSegments(&(p1->line[c1].point[v1-1]), &(p1->line[c1].point[v1]), &(p2->line[c2].point[v2-1]), &(p2->line[c2].point[v2])) ==  MS_TRUE)     
      return(MS_TRUE);

  /*
  ** At this point we know there are are no intersections between edges. There may be other tests necessary
  ** but I haven't run into any cases that require them.
  */

  return(MS_FALSE);
}


/*
** Distance computations
*/

double msDistancePointToPoint(pointObj *a, pointObj *b)
{
  double d;
  double dx, dy;
  
  dx = a->x - b->x;
  dy = a->y - b->y;
  d = sqrt(dx*dx + dy*dy);
  return(d);
}

double msDistancePointToSegment(pointObj *p, pointObj *a, pointObj *b)
{
  double l; /* length of line ab */
  double r,s;

  l = msDistancePointToPoint(a,b);

  if(l == 0.0) /* a = b */
    return( msDistancePointToPoint(a,p));

  r = ((a->y - p->y)*(a->y - b->y) - (a->x - p->x)*(b->x - a->x))/(l*l);

  if(r > 1) /* perpendicular projection of P is on the forward extention of AB */
    return(MS_MIN(msDistancePointToPoint(p, b),msDistancePointToPoint(p, a)));
  if(r < 0) /* perpendicular projection of P is on the backward extention of AB */
    return(MS_MIN(msDistancePointToPoint(p, b),msDistancePointToPoint(p, a)));

  s = ((a->y - p->y)*(b->x - a->x) - (a->x - p->x)*(b->y - a->y))/(l*l);

  return(fabs(s*l));
}

#define SMALL_NUMBER 0.00000001
#define dot(u,v) ((u).x *(v).x + (u).y *(v).y) /* vector dot product */
#define norm(v) sqrt(dot(v,v))

#define slope(a,b) (((a)->y - (b)->y)/((a)->x - (b)->x))

/* Segment to segment distance code is a modified version of that found at:  */
/*  */
/* http://www.geometryalgorithms.com/Archive/algorithm_0106/algorithm_0106.htm */
/*  */
/* Copyright 2001, softSurfer (www.softsurfer.com) */
/* This code may be freely used and modified for any purpose */
/* providing that this copyright notice is included with it. */
/* SoftSurfer makes no warranty for this code, and cannot be held */
/* liable for any real or imagined damage resulting from its use. */
/* Users of this code must verify correctness for their application. */

double msDistanceSegmentToSegment(pointObj *pa, pointObj *pb, pointObj *pc, pointObj *pd) 
{
  vectorObj dP;
  vectorObj u, v, w;
  double a, b, c, d, e; 
  double D;
  double sc, sN, sD; /* N=numerator, D=demoninator */
  double tc, tN, tD;

  /* check for strictly parallel segments first */
  /* if(((pa->x == pb->x) && (pc->x == pd->x)) || (slope(pa,pb) == slope(pc,pd))) { // vertical (infinite slope) || otherwise parallel */
  /* D = msDistancePointToSegment(pa, pc, pd); */
  /* D = MS_MIN(D, msDistancePointToSegment(pb, pc, pd)); */
  /* D = MS_MIN(D, msDistancePointToSegment(pc, pa, pb)); */
  /* return(MS_MIN(D, msDistancePointToSegment(pd, pa, pb))); */
  /* } */

  u.x = pb->x - pa->x; /* u = pb - pa */
  u.y = pb->y - pa->y;
  v.x = pd->x - pc->x; /* v = pd - pc  */
  v.y = pd->y - pc->y; 
  w.x = pa->x - pc->x; /* w = pa - pc */
  w.y = pa->y - pc->y; 

  a = dot(u,u);
  b = dot(u,v);
  c = dot(v,v);
  d = dot(u,w);
  e = dot(v,w);

  D = a*c - b*b;
  sc = sN = sD = D;
  tc = tN = tD = D;
  
  /* compute the line parameters of the two closest points */
  if(D < SMALL_NUMBER) { /* lines are parallel or almost parallel */
    sN = 0.0;
    sD = 1.0;
    tN = e;
    tD = c;
  } else { /* get the closest points on the infinite lines */
    sN = b*e - c*d;
    tN = a*e - b*d;
    if(sN < 0) {
      sN = 0.0;
      tN = e;
      tD = c;
    } else if(sN > sD) {
      sN = sD;
      tN = e + b;
      tD = c;
    }
  }

  if(tN < 0) {
    tN = 0.0;
    if(-d < 0)
      sN = 0.0;
    else if(-d > a)
      sN = sD;
    else {
      sN = -d;
      sD = a;
    }
  } else if(tN > tD) {
    tN = tD;
    if((-d + b) < 0)
      sN = 0.0;
    else if((-d + b) > a)
      sN = sD;
    else {
      sN = (-d + b);
      sD = a;
    }
  }

  /* finally do the division to get sc and tc */
  sc = sN/sD;
  tc = tN/tD;

  dP.x = w.x + (sc*u.x) - (tc*v.x);
  dP.y = w.y + (sc*u.y) - (tc*v.y);

  return(norm(dP));
}

double msDistancePointToShape(pointObj *point, shapeObj *shape)
{
  int i, j;
  double dist, minDist=-1;

  switch(shape->type) {
  case(MS_SHAPE_POINT):
    for(j=0;j<shape->numlines;j++) {
      for(i=0; i<shape->line[j].numpoints; i++) {
        dist = msDistancePointToPoint(point, &(shape->line[j].point[i]));
        if((dist < minDist) || (minDist < 0)) minDist = dist;
      }
    }
    break;
  case(MS_SHAPE_LINE):
    for(j=0;j<shape->numlines;j++) {
      for(i=1; i<shape->line[j].numpoints; i++) {
        dist = msDistancePointToSegment(point, &(shape->line[j].point[i-1]), &(shape->line[j].point[i]));
        if((dist < minDist) || (minDist < 0)) minDist = dist;
      }
    }
    break;
  case(MS_SHAPE_POLYGON):
    if(msIntersectPointPolygon(point, shape))
      minDist = 0; /* point is IN the shape */
    else { /* treat shape just like a line */
      for(j=0;j<shape->numlines;j++) {
        for(i=1; i<shape->line[j].numpoints; i++) {
          dist = msDistancePointToSegment(point, &(shape->line[j].point[i-1]), &(shape->line[j].point[i]));
          if((dist < minDist) || (minDist < 0)) minDist = dist;
        }
      }
    }
    break;
  default:
    break;
  }

  return(minDist);
}

double msDistanceShapeToShape(shapeObj *shape1, shapeObj *shape2)
{
  int i,j,k,l;
  double dist, minDist=-1;

  switch(shape1->type) {
  case(MS_SHAPE_POINT): /* shape1 */
    for(i=0;i<shape1->numlines;i++) {
      for(j=0; j<shape1->line[i].numpoints; j++) {
        dist = msDistancePointToShape(&(shape1->line[i].point[j]), shape2);
        if((dist < minDist) || (minDist < 0)) 
    minDist = dist;
      }
    }
    break;
  case(MS_SHAPE_LINE): /* shape1 */
    switch(shape2->type) {
    case(MS_SHAPE_POINT):
      for(i=0;i<shape2->numlines;i++) {
        for(j=0; j<shape2->line[i].numpoints; j++) {
          dist = msDistancePointToShape(&(shape2->line[i].point[j]), shape1);
          if((dist < minDist) || (minDist < 0)) 
      minDist = dist;
        }
      }
      break;
    case(MS_SHAPE_LINE):
      for(i=0;i<shape1->numlines;i++) {
        for(j=1; j<shape1->line[i].numpoints; j++) {
          for(k=0;k<shape2->numlines;k++) {
            for(l=1; l<shape2->line[k].numpoints; l++) {
              /* check intersection (i.e. dist=0) */
        if(msIntersectSegments(&(shape1->line[i].point[j-1]), &(shape1->line[i].point[j]), &(shape2->line[k].point[l-1]), &(shape2->line[k].point[l])) == MS_TRUE) 
                return(0);

        /* no intersection, compute distance */
        dist = msDistanceSegmentToSegment(&(shape1->line[i].point[j-1]), &(shape1->line[i].point[j]), &(shape2->line[k].point[l-1]), &(shape2->line[k].point[l]));
        if((dist < minDist) || (minDist < 0)) 
    minDist = dist;
      }
    }
  }
      }
      break;    
    case(MS_SHAPE_POLYGON):
      /* shape2 (the polygon) could contain shape1 or one of it's parts       */
      for(i=0; i<shape1->numlines; i++) {
        if(msIntersectPointPolygon(&(shape1->line[0].point[0]), shape2) == MS_TRUE) /* this considers holes and multiple parts */
          return(0);
      }
      
      /* check segment intersection and, if necessary, distance between segments */
      for(i=0;i<shape1->numlines;i++) {
        for(j=1; j<shape1->line[i].numpoints; j++) {
          for(k=0;k<shape2->numlines;k++) {
            for(l=1; l<shape2->line[k].numpoints; l++) {
        /* check intersection (i.e. dist=0) */
        if(msIntersectSegments(&(shape1->line[i].point[j-1]), &(shape1->line[i].point[j]), &(shape2->line[k].point[l-1]), &(shape2->line[k].point[l])) == MS_TRUE) 
                return(0);

        /* no intersection, compute distance */
        dist = msDistanceSegmentToSegment(&(shape1->line[i].point[j-1]), &(shape1->line[i].point[j]), &(shape2->line[k].point[l-1]), &(shape2->line[k].point[l]));
        if((dist < minDist) || (minDist < 0)) 
    minDist = dist;
      }
    }
  }
      }
      break;
    }
    break;
  case(MS_SHAPE_POLYGON): /* shape1 */
    switch(shape2->type) {
    case(MS_SHAPE_POINT):
      for(i=0;i<shape2->numlines;i++) {
        for(j=0; j<shape2->line[i].numpoints; j++) {
          dist = msDistancePointToShape(&(shape2->line[i].point[j]), shape1);
          if((dist < minDist) || (minDist < 0)) 
      minDist = dist;
        }
      }
      break;
    case(MS_SHAPE_LINE):
      /* shape1 (the polygon) could contain shape2 or one of it's parts       */
      for(i=0; i<shape2->numlines; i++) {
        if(msIntersectPointPolygon(&(shape2->line[i].point[0]), shape1) == MS_TRUE) /* this considers holes and multiple parts */
          return(0);
      }
      
      /* check segment intersection and, if necessary, distance between segments */
      for(i=0;i<shape1->numlines;i++) {      
        for(j=1; j<shape1->line[i].numpoints; j++) {
          for(k=0;k<shape2->numlines;k++) {
            for(l=1; l<shape2->line[k].numpoints; l++) {
        /* check intersection (i.e. dist=0) */
        if(msIntersectSegments(&(shape1->line[i].point[j-1]), &(shape1->line[i].point[j]), &(shape2->line[k].point[l-1]), &(shape2->line[k].point[l])) == MS_TRUE) 
                return(0);

        /* no intersection, compute distance */
        dist = msDistanceSegmentToSegment(&(shape1->line[i].point[j-1]), &(shape1->line[i].point[j]), &(shape2->line[k].point[l-1]), &(shape2->line[k].point[l]));
        if((dist < minDist) || (minDist < 0)) 
    minDist = dist;
      }
    }
  }
      }
      break; 
    case(MS_SHAPE_POLYGON): 
      /* shape1 completely contains shape2 (only need to check one point from each part) */
      for(i=0; i<shape2->numlines; i++) {
        if(msIntersectPointPolygon(&(shape2->line[i].point[0]), shape1) == MS_TRUE) /* this considers holes and multiple parts */
          return(0);
      }

      /* shape2 completely contains shape1 (only need to check one point from each part) */
      for(i=0; i<shape1->numlines; i++) {
        if(msIntersectPointPolygon(&(shape1->line[i].point[0]), shape2) == MS_TRUE) /* this considers holes and multiple parts */
          return(0);
      }

      /* check segment intersection and, if necessary, distance between segments */
      for(i=0;i<shape1->numlines;i++) {        
        for(j=1; j<shape1->line[i].numpoints; j++) {
          for(k=0;k<shape2->numlines;k++) {
            for(l=1; l<shape2->line[k].numpoints; l++) {
        /* check intersection (i.e. dist=0) */
        if(msIntersectSegments(&(shape1->line[i].point[j-1]), &(shape1->line[i].point[j]), &(shape2->line[k].point[l-1]), &(shape2->line[k].point[l])) == MS_TRUE) 
                return(0);        

        /* no intersection, compute distance */
        dist = msDistanceSegmentToSegment(&(shape1->line[i].point[j-1]), &(shape1->line[i].point[j]), &(shape2->line[k].point[l-1]), &(shape2->line[k].point[l]));
        if((dist < minDist) || (minDist < 0)) 
    minDist = dist;
      }
    }
  }
      }
      break;
    }
    break;
  }

  return(minDist);
}

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