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/*!
* \file lib/raster/align_window.c
*
* \brief GIS Library - Window alignment functions.
*
* (C) 2001-2009 by the GRASS Development Team
*
* This program is free software under the GNU General Public License
* (>=v2). Read the file COPYING that comes with GRASS for details.
*
* \author Original author CERL
*/
#include <stdio.h>
#include <math.h>
#include <grass/gis.h>
#include <grass/raster.h>
/*!
* \brief Align two regions.
*
* Modifies the input <i>window</i> to align to <i>ref</i> region. The
* resolutions in <i>window</i> are set to match those in <i>ref</i>
* and the <i>window</i> edges (north, south, east, west) are modified
* to align with the grid of the <i>ref</i> region.
*
* The <i>window</i> may be enlarged if necessary to achieve the
* alignment. The north is rounded northward, the south southward,
* the east eastward and the west westward. Lon-lon constraints are
* taken into consideration to make sure that the north doesn't go
* above 90 degrees (for lat/lon) or that the east does "wrap" past
* the west, etc.
*
* \param[in,out] window pointer to Cell_head to be modified
* \param ref pointer to Cell_head
*
* \return NULL on success
*/
void Rast_align_window(struct Cell_head *window, const struct Cell_head *ref)
{
G_debug(1, "Rast_align_window()");
window->ns_res = ref->ns_res;
window->ew_res = ref->ew_res;
window->zone = ref->zone;
window->proj = ref->proj;
G_debug(1, "before alignment:");
G_debug(1, "North: %.15g", window->north);
G_debug(1, "South: %.15g", window->south);
G_debug(1, "West: %.15g", window->west);
G_debug(1, "East: %.15g", window->east);
window->north =
ref->north -
floor((ref->north - window->north) / ref->ns_res) * ref->ns_res;
window->south =
ref->south -
ceil((ref->south - window->south) / ref->ns_res) * ref->ns_res;
/* Rast_easting_to_col() wraps easting:
* east can become < west, or both west and east are shifted */
window->west = ref->west + floor((window->west - ref->west) / ref->ew_res) *
ref->ew_res;
window->east = ref->east +
ceil((window->east - ref->east) / ref->ew_res) * ref->ew_res;
if (window->proj == PROJECTION_LL) {
while (window->north > 90.0 + window->ns_res / 2.0)
window->north -= window->ns_res;
while (window->south < -90.0 - window->ns_res / 2.0)
window->south += window->ns_res;
}
G_debug(1, "after alignment:");
G_debug(1, "North: %.15g", window->north);
G_debug(1, "South: %.15g", window->south);
G_debug(1, "West: %.15g", window->west);
G_debug(1, "East: %.15g", window->east);
G_adjust_Cell_head(window, 0, 0);
}
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