Function msGetMeasureUsingPoint

maputil.c:1176–1246

/ pointObj *msGetMeasureUsingPoint(shapeObj *shape, pointObj */ point) */ / Calculate the intersection point betwwen the point and the */ shape and return the Measured value at the intersection. */ /

/*      shape and return the Measured value at the intersection.        */
/************************************************************************/
pointObj *msGetMeasureUsingPoint(shapeObj *shape, pointObj *point)
{       
    double      dfMinDist = 1e35;
    double      dfDist = 0;
    pointObj    oFirst;
    pointObj    oSecond;
    int         i, j = 0;
    lineObj     line;
    pointObj    *poIntersectionPt = NULL;
    double      dfFactor = 0;
    double      dfDistTotal, dfDistToIntersection = 0;

    if (shape && point)
    {
        for (i=0; i<shape->numlines; i++)
        {
            line = shape->line[i];
/* -------------------------------------------------------------------- */
/*      for each line (2 consecutive lines) get the distance between    */
/*      the line and the point and determine which line segment is      */
/*      the closeset to the point.                                      */
/* -------------------------------------------------------------------- */
            for (j=0; j<line.numpoints-1; j++)
            {
                dfDist = msDistancePointToSegment(point, &line.point[j], &line.point[j+1]);
                if (dfDist < dfMinDist)
                {
                    oFirst.x = line.point[j].x;
                    oFirst.y = line.point[j].y;
#ifdef USE_POINT_Z_M
                    oFirst.m = line.point[j].m;
#endif
                    
                    oSecond.x =  line.point[j+1].x;
                    oSecond.y =  line.point[j+1].y;
#ifdef USE_POINT_Z_M
                    oSecond.m =  line.point[j+1].m;
#endif

                    dfMinDist = dfDist;
                }
            }
        }
/* -------------------------------------------------------------------- */
/*      once we have the nearest segment, look for the x,y location     */
/*      which is the nearest intersection between the line and the      */
/*      point.                                                          */
/* -------------------------------------------------------------------- */
        poIntersectionPt = msIntersectionPointLine(point, &oFirst, &oSecond);
        if (poIntersectionPt)
        {
            dfDistTotal = sqrt(((oSecond.x - oFirst.x)*(oSecond.x - oFirst.x)) + 
                               ((oSecond.y - oFirst.y)*(oSecond.y - oFirst.y)));

            dfDistToIntersection = sqrt(((poIntersectionPt->x - oFirst.x)*
                                         (poIntersectionPt->x - oFirst.x)) + 
                                        ((poIntersectionPt->y - oFirst.y)*
                                         (poIntersectionPt->y - oFirst.y)));