source: grass/trunk/lib/rst/data/dataquad.c

/*!
 * \file qtree.c
 *
 * \author
 * H. Mitasova, I. Kosinovsky, D. Gerdes, Fall 1993,
 * University of Illinois and
 * US Army Construction Engineering Research Lab
 *
 * \author H. Mitasova (University of Illinois),
 * \author I. Kosinovsky, (USA-CERL)
 * \author D.Gerdes (USA-CERL)
 *
 * \author modified by H. Mitasova, November 1996 (include variable smoothing)
 *
 * \copyright
 * (C) 1993-1996 by Helena Mitasova and the GRASS Development Team
 *
 * \copyright
 * This program is free software under the
 * GNU General Public License (>=v2).
 * Read the file COPYING that comes with GRASS for details.
 */


#include <stdio.h>
#include <stdlib.h>
#include <grass/dataquad.h>


/*!
 * Initialize point structure with given arguments
 *
 * This is a constructor of the point structure and it allocates memory.
 *
 * \note
 * Smoothing is part of the point structure
 */
struct triple *quad_point_new(double x, double y, double z, double sm)
{
    struct triple *point;

    if (!(point = (struct triple *)malloc(sizeof(struct triple)))) {
        return NULL;
    }

    point->x = x;
    point->y = y;
    point->z = z;
    point->sm = sm;

    return point;
}


/*!
 * Initialize quaddata structure with given arguments
 * 
 * This is a constructor of the quaddata structure and it allocates memory.
 * It also creates (and allocates memory for) the given number of points
 * (given by *kmax*). The point attributes are set to zero.
 */
struct quaddata *quad_data_new(double x_or, double y_or, double xmax,
                               double ymax, int rows, int cols, int n_points,
                               int kmax)
{
    struct quaddata *data;
    int i;

    if (!(data = (struct quaddata *)malloc(sizeof(struct quaddata)))) {
        return NULL;
    }

    data->x_orig = x_or;
    data->y_orig = y_or;
    data->xmax = xmax;
    data->ymax = ymax;
    data->n_rows = rows;
    data->n_cols = cols;
    data->n_points = n_points;
    data->points =
        (struct triple *)malloc(sizeof(struct triple) * (kmax + 1));
    if (!data->points)
        return NULL;
    for (i = 0; i <= kmax; i++) {
        data->points[i].x = 0.;
        data->points[i].y = 0.;
        data->points[i].z = 0.;
        data->points[i].sm = 0.;
    }

    return data;
}


/*!
 * Return the quadrant the point should be inserted in
 */
int quad_compare(struct triple *point, struct quaddata *data)
{
    int cond1, cond2, cond3, cond4, rows, cols;
    double ew_res, ns_res;

    ew_res = (data->xmax - data->x_orig) / data->n_cols;
    ns_res = (data->ymax - data->y_orig) / data->n_rows;


    if (data == NULL)
        return -1;
    if (data->n_rows % 2 == 0) {
        rows = data->n_rows / 2;
    }
    else {
        rows = (int)(data->n_rows / 2) + 1;
    }

    if (data->n_cols % 2 == 0) {
        cols = data->n_cols / 2;
    }
    else {
        cols = (int)(data->n_cols / 2) + 1;
    }
    cond1 = (point->x >= data->x_orig);
    cond2 = (point->x >= data->x_orig + ew_res * cols);
    cond3 = (point->y >= data->y_orig);
    cond4 = (point->y >= data->y_orig + ns_res * rows);
    if (cond1 && cond3) {
        if (cond2 && cond4)
            return NE;
        if (cond2)
            return SE;
        if (cond4)
            return NW;
        return SW;
    }
    else
        return 0;
}


/*!
 * Add point to a given *data*.
 */
int quad_add_data(struct triple *point, struct quaddata *data, double dmin)
{
    int n, i, cond;
    double xx, yy, r;

    cond = 1;
    if (data == NULL) {
        fprintf(stderr, "add_data: data is NULL \n");
        return -5;
    }
    for (i = 0; i < data->n_points; i++) {
        xx = data->points[i].x - point->x;
        yy = data->points[i].y - point->y;
        r = xx * xx + yy * yy;
        if (r <= dmin) {
            cond = 0;
            break;
        }
    }

    if (cond) {
        n = (data->n_points)++;
        data->points[n].x = point->x;
        data->points[n].y = point->y;
        data->points[n].z = point->z;
        data->points[n].sm = point->sm;
    }
    return cond;
}


/*!
 * Check intersection of two quaddata structures
 * 
 * Checks if region defined by *data* intersects the region defined
 * by *data_inter*.
 */
int quad_intersect(struct quaddata *data_inter, struct quaddata *data)
{
    double xmin, xmax, ymin, ymax;

    xmin = data_inter->x_orig;
    xmax = data_inter->xmax;
    ymin = data_inter->y_orig;
    ymax = data_inter->ymax;

    if (((data->x_orig >= xmin) && (data->x_orig <= xmax)
         && (((data->y_orig >= ymin) && (data->y_orig <= ymax))
             || ((ymin >= data->y_orig) && (ymin <= data->ymax))
         )
        )
        || ((xmin >= data->x_orig) && (xmin <= data->xmax)
            && (((ymin >= data->y_orig) && (ymin <= data->ymax))
                || ((data->y_orig >= ymin) && (data->y_orig <= ymax))
            )
        )
        ) {
        return 1;
    }
    else
        return 0;
}


/*!
 * Check if *data* needs to be divided
 * 
 * Checks if *data* needs to be divided. If `data->points` is empty,
 * returns -1; if its not empty but there aren't enough points
 * in *data* for division returns 0. Otherwise (if its not empty and
 * there are too many points) returns 1.
 * 
 * \returns 1 if division is needed
 * \returns 0 if division is not needed
 * \returns -1 if there are no points
 */
int quad_division_check(struct quaddata *data, int kmax)
{
    if (data->points == NULL)
        return -1;
    if (data->n_points < kmax)
        return 0;
    else
        return 1;
}


/*!
 * Divide *data* into four new ones
 *
 * Divides *data* into 4 new datas reinserting `data->points` in
 * them by calling data function `quad_compare()` to determine
 * were to insert. Returns array of 4 new datas (allocates memory).
 */
struct quaddata **quad_divide_data(struct quaddata *data, int kmax,
                                   double dmin)
{
    struct quaddata **datas;
    int cols1, cols2, rows1, rows2, i;  /*j1, j2, jmin = 0; */
    double dx, dy;              /* x2, y2, dist, mindist; */
    double xr, xm, xl, yr, ym, yl;      /* left, right, middle coord */
    double ew_res, ns_res;

    ew_res = (data->xmax - data->x_orig) / data->n_cols;
    ns_res = (data->ymax - data->y_orig) / data->n_rows;

    if ((data->n_cols <= 1) || (data->n_rows <= 1)) {
        fprintf(stderr,
                "Points are too concentrated -- please increase DMIN\n");
        exit(0);
    }

    if (data->n_cols % 2 == 0) {
        cols1 = data->n_cols / 2;
        cols2 = cols1;
    }
    else {
        cols2 = (int)(data->n_cols / 2);
        cols1 = cols2 + 1;
    }
    if (data->n_rows % 2 == 0) {
        rows1 = data->n_rows / 2;
        rows2 = rows1;
    }
    else {
        rows2 = (int)(data->n_rows / 2);
        rows1 = rows2 + 1;
    }

    dx = cols1 * ew_res;
    dy = rows1 * ns_res;

    xl = data->x_orig;
    xm = xl + dx;
    xr = data->xmax;
    yl = data->y_orig;
    ym = yl + dy;
    yr = data->ymax;

    if (!(datas = (struct quaddata **)malloc(sizeof(struct quaddata *) * 5))) {
        return NULL;
    }
    datas[NE] = quad_data_new(xm, ym, xr, yr, rows2, cols2, 0, kmax);
    datas[SW] = quad_data_new(xl, yl, xm, ym, rows1, cols1, 0, kmax);
    datas[SE] = quad_data_new(xm, yl, xr, ym, rows1, cols2, 0, kmax);
    datas[NW] = quad_data_new(xl, ym, xm, yr, rows2, cols1, 0, kmax);
    for (i = 0; i < data->n_points; i++) {
        switch (quad_compare(data->points + i, data)) {
        case SW:
            {
                quad_add_data(data->points + i, datas[SW], dmin);
                break;
            }
        case SE:
            {
                quad_add_data(data->points + i, datas[SE], dmin);
                break;
            }
        case NW:
            {
                quad_add_data(data->points + i, datas[NW], dmin);
                break;
            }
        case NE:
            {
                quad_add_data(data->points + i, datas[NE], dmin);
                break;
            }
        }
    }
    data->points = NULL;
    return datas;
}


/*!
 * Gets such points from *data* that lie within region determined by
 * *data_inter*. Called by tree function `region_data()`.
 */
int
quad_get_points(struct quaddata *data_inter, struct quaddata *data, int MAX)
{
    int i, ind;
    int n = 0;
    int l = 0;
    double xmin, xmax, ymin, ymax;
    struct triple *point;

    xmin = data_inter->x_orig;
    xmax = data_inter->xmax;
    ymin = data_inter->y_orig;
    ymax = data_inter->ymax;
    for (i = 0; i < data->n_points; i++) {
        point = data->points + i;
        if (l >= MAX)
            return MAX + 1;
        if ((point->x > xmin) && (point->x < xmax)
            && (point->y > ymin) && (point->y < ymax)) {
            ind = data_inter->n_points++;
            data_inter->points[ind].x = point->x;
            data_inter->points[ind].y = point->y;
            data_inter->points[ind].z = point->z;
            data_inter->points[ind].sm = point->sm;
            l = l + 1;

        }
    }
    n = l;
    return (n);
}