postgis/liblwgeom/g_box.c

/**********************************************************************
 * $Id$
 *
 * PostGIS - Spatial Types for PostgreSQL
 * Copyright 2009 Paul Ramsey <pramsey@cleverelephant.ca>
 *
 * This is free software; you can redistribute and/or modify it under
 * the terms of the GNU General Public Licence. See the COPYING file.
 *
 **********************************************************************/

#include "libgeom.h"
#include <math.h>
#include <stdlib.h>

GBOX* gbox_new(uchar flags)
{
	GBOX *g = (GBOX*)lwalloc(sizeof(GBOX));
	g->flags = flags;
	return g;
}

int gbox_merge_point3d(POINT3D p, GBOX *gbox)
{
	if( gbox->xmin > p.x ) gbox->xmin = p.x;
	if( gbox->ymin > p.y ) gbox->ymin = p.y;
	if( gbox->zmin > p.z ) gbox->zmin = p.z;
	if( gbox->xmax < p.x ) gbox->xmax = p.x;
	if( gbox->ymax < p.y ) gbox->ymax = p.y;
	if( gbox->zmax < p.z ) gbox->zmax = p.z;
	return G_SUCCESS;
}

int gbox_contains_point3d(GBOX gbox, POINT3D pt)
{
	if( gbox.xmin > pt.x || gbox.ymin > pt.y || gbox.zmin > pt.z ||
	    gbox.xmax < pt.x || gbox.ymax < pt.y || gbox.zmax < pt.z )
	{
		return LW_FALSE;
	}
	return LW_TRUE;
}

int gbox_merge(GBOX new_box, GBOX *merge_box)
{
	assert(merge_box);
	
	if( merge_box->flags != new_box.flags ) 
		return G_FAILURE;
	
	if( new_box.xmin < merge_box->xmin) merge_box->xmin = new_box.xmin;
	if( new_box.ymin < merge_box->ymin) merge_box->ymin = new_box.ymin;
	if( new_box.xmax > merge_box->xmax) merge_box->xmax = new_box.xmax;
	if( new_box.ymax > merge_box->ymax) merge_box->ymax = new_box.ymax;
	
	if( FLAGS_GET_Z(merge_box->flags) || FLAGS_GET_GEODETIC(merge_box->flags) )
	{
		if( new_box.zmin < merge_box->zmin) merge_box->zmin = new_box.zmin;
		if( new_box.zmax > merge_box->zmax) merge_box->zmax = new_box.zmax;
	}
	if( FLAGS_GET_M(merge_box->flags) )
	{
		if( new_box.mmin < merge_box->mmin) merge_box->mmin = new_box.mmin;
		if( new_box.mmax > merge_box->mmax) merge_box->mmax = new_box.mmax;
	}

	return G_SUCCESS;
}

int gbox_overlaps(GBOX g1, GBOX g2)
{
	if( g1.flags != g2.flags )
		lwerror("gbox_overlaps: geometries have mismatched dimensionality");
		
	if( g1.xmax < g2.xmin || g1.ymax < g2.ymin ||
	    g1.xmin > g2.xmax || g1.ymin > g2.ymax )
		return LW_FALSE;
	if( FLAGS_GET_Z(g1.flags) || FLAGS_GET_GEODETIC(g1.flags) )
	{
		if( g1.zmax < g2.zmin || g1.zmin > g2.zmax )
			return LW_FALSE;
	}
	if( FLAGS_GET_M(g1.flags) )
	{
		if( g1.mmax < g2.mmin || g1.mmin > g2.mmax )
			return LW_FALSE;
	}
	return LW_TRUE;
}

/**
* Warning, this function is only good for x/y/z boxes, used 
* in unit testing of geodetic box generation.
*/
GBOX* gbox_from_string(char *str)
{
    char *ptr = str;
    char *nextptr;
    char *gbox_start = strstr(str, "GBOX((");
    GBOX *gbox = gbox_new(gflags(0,0,1));
    if( ! gbox_start ) return NULL; /* No header found */
    ptr += 6;
    gbox->xmin = strtod(ptr, &nextptr);
    if( ptr == nextptr ) return NULL; /* No double found */
    ptr = nextptr + 1;
    gbox->ymin = strtod(ptr, &nextptr);
    if( ptr == nextptr ) return NULL; /* No double found */
    ptr = nextptr + 1;
    gbox->zmin = strtod(ptr, &nextptr);
    if( ptr == nextptr ) return NULL; /* No double found */
    ptr = nextptr + 3;
    gbox->xmax = strtod(ptr, &nextptr);
    if( ptr == nextptr ) return NULL; /* No double found */
    ptr = nextptr + 1;
    gbox->ymax = strtod(ptr, &nextptr);
    if( ptr == nextptr ) return NULL; /* No double found */
    ptr = nextptr + 1;
    gbox->zmax = strtod(ptr, &nextptr);
    if( ptr == nextptr ) return NULL; /* No double found */
    return gbox;
}

char* gbox_to_string(GBOX *gbox)
{
	static int sz = 128;
	char *str = NULL;

	if( ! gbox ) 
		return strdup("NULL POINTER");

	str = (char*)lwalloc(sz);

	if( FLAGS_GET_GEODETIC(gbox->flags) )
	{
		snprintf(str, sz, "GBOX((%.8g,%.8g,%.8g),(%.8g,%.8g,%.8g))", gbox->xmin, gbox->ymin, gbox->zmin, gbox->xmax, gbox->ymax, gbox->zmax);
		return str;
	}
	if( FLAGS_GET_Z(gbox->flags) && FLAGS_GET_M(gbox->flags) )
	{
		snprintf(str, sz, "GBOX((%.8g,%.8g,%.8g,%.8g),(%.8g,%.8g,%.8g,%.8g))", gbox->xmin, gbox->ymin, gbox->zmin, gbox->mmin, gbox->xmax, gbox->ymax, gbox->zmax, gbox->mmax);
		return str;
	}
	if( FLAGS_GET_Z(gbox->flags) )
	{
		snprintf(str, sz, "GBOX((%.8g,%.8g,%.8g),(%.8g,%.8g,%.8g))", gbox->xmin, gbox->ymin, gbox->zmin, gbox->xmax, gbox->ymax, gbox->zmax);
		return str;
	}
	if( FLAGS_GET_M(gbox->flags) )
	{
		snprintf(str, sz, "GBOX((%.8g,%.8g,%.8g),(%.8g,%.8g,%.8g))", gbox->xmin, gbox->ymin, gbox->mmin, gbox->xmax, gbox->ymax, gbox->mmax);
		return str;
	}
	snprintf(str, sz, "GBOX((%.8g,%.8g),(%.8g,%.8g))", gbox->xmin, gbox->ymin, gbox->xmax, gbox->ymax);
	return str;
}

GBOX* gbox_copy(GBOX *box)
{
	GBOX *copy = (GBOX*)lwalloc(sizeof(GBOX));
	memcpy(copy, box, sizeof(GBOX));
	return copy;
}

void gbox_duplicate(GBOX original, GBOX *duplicate)
{
    assert(duplicate);

	if( original.flags != duplicate->flags )
		lwerror("gbox_duplicate: geometries have inconsistent dimensionality");
		
    duplicate->xmin = original.xmin;
    duplicate->ymin = original.ymin;
    duplicate->xmax = original.xmax;
    duplicate->ymax = original.ymax;

    if( FLAGS_GET_GEODETIC(original.flags) || FLAGS_GET_Z(original.flags) )
	{
        duplicate->zmin = original.zmin;
        duplicate->zmax = original.zmax;
	}
	if( FLAGS_GET_M(original.flags) )
	{
        duplicate->mmin = original.mmin;
        duplicate->mmax = original.mmax;
	}
    return;
}

size_t gbox_serialized_size(uchar flags)
{
	if( ! FLAGS_GET_BBOX(flags) ) return 0;
    if( FLAGS_GET_GEODETIC(flags) )
        return 6 * sizeof(float);
    else
        return 2 * FLAGS_NDIMS(flags) * sizeof(float);
}


/* ********************************************************************************
** Compute cartesian bounding GBOX boxes from LWGEOM.
*/

static int lwcircle_calculate_gbox(POINT4D p1, POINT4D p2, POINT4D p3, GBOX *gbox)
{
	double x1, x2, y1, y2, z1, z2, m1, m2;
	double angle, radius, sweep;
	/* angles from center */
	double a1, a2, a3;
	/* angles from center once a1 is rotated to zero */
	double r2, r3;
	double xe = 0.0, ye = 0.0;
	POINT4D *center;
	int i;

	LWDEBUG(2, "lwcircle_calculate_gbox called.");

	radius = lwcircle_center(&p1, &p2, &p3, &center);
	if (radius < 0.0) return G_FAILURE;

	x1 = MAXFLOAT;
	x2 = -1 * MAXFLOAT;
	y1 = MAXFLOAT;
	y2 = -1 * MAXFLOAT;

	a1 = atan2(p1.y - center->y, p1.x - center->x);
	a2 = atan2(p2.y - center->y, p2.x - center->x);
	a3 = atan2(p3.y - center->y, p3.x - center->x);

	/* Rotate a2 and a3 such that a1 = 0 */
	r2 = a2 - a1;
	r3 = a3 - a1;

	/*
	 * There are six cases here I'm interested in
	 * Clockwise:
	 *   1. a1-a2 < 180 == r2 < 0 && (r3 > 0 || r3 < r2)
	 *   2. a1-a2 > 180 == r2 > 0 && (r3 > 0 && r3 < r2)
	 *   3. a1-a2 > 180 == r2 > 0 && (r3 > r2 || r3 < 0)
	 * Counter-clockwise:
	 *   4. a1-a2 < 180 == r2 > 0 && (r3 < 0 || r3 > r2)
	 *   5. a1-a2 > 180 == r2 < 0 && (r3 < 0 && r3 > r2)
	 *   6. a1-a2 > 180 == r2 < 0 && (r3 < r2 || r3 > 0)
	 * 3 and 6 are invalid cases where a3 is the midpoint.
	 * BBOX is fundamental, so these cannot error out and will instead
	 * calculate the sweep using a3 as the middle point.
	 */

	/* clockwise 1 */
	if (FP_LT(r2, 0) && (FP_GT(r3, 0) || FP_LT(r3, r2)))
	{
		sweep = (FP_GT(r3, 0)) ? (r3 - 2 * M_PI) : r3;
	}
	/* clockwise 2 */
	else if (FP_GT(r2, 0) && FP_GT(r3, 0) && FP_LT(r3, r2))
	{
		sweep = (FP_GT(r3, 0)) ? (r3 - 2 * M_PI) : r3;
	}
	/* counter-clockwise 4 */
	else if (FP_GT(r2, 0) && (FP_LT(r3, 0) || FP_GT(r3, r2)))
	{
		sweep = (FP_LT(r3, 0)) ? (r3 + 2 * M_PI) : r3;
	}
	/* counter-clockwise 5 */
	else if (FP_LT(r2, 0) && FP_LT(r3, 0) && FP_GT(r3, r2))
	{
		sweep = (FP_LT(r3, 0)) ? (r3 + 2 * M_PI) : r3;
	}
	/* clockwise invalid 3 */
	else if (FP_GT(r2, 0) && (FP_GT(r3, r2) || FP_LT(r3, 0)))
	{
		sweep = (FP_GT(r2, 0)) ? (r2 - 2 * M_PI) : r2;
	}
	/* clockwise invalid 6 */
	else
	{
		sweep = (FP_LT(r2, 0)) ? (r2 + 2 * M_PI) : r2;
	}

	LWDEBUGF(3, "a1 %.16f, a2 %.16f, a3 %.16f, sweep %.16f", a1, a2, a3, sweep);

	angle = 0.0;
	for (i=0; i < 6; i++)
	{
		switch (i)
		{
			/* right extent */
		case 0:
			angle = 0.0;
			xe = center->x + radius;
			ye = center->y;
			break;
			/* top extent */
		case 1:
			angle = M_PI_2;
			xe = center->x;
			ye = center->y + radius;
			break;
			/* left extent */
		case 2:
			angle = M_PI;
			xe = center->x - radius;
			ye = center->y;
			break;
			/* bottom extent */
		case 3:
			angle = -1 * M_PI_2;
			xe = center->x;
			ye = center->y - radius;
			break;
			/* first point */
		case 4:
			angle = a1;
			xe = p1.x;
			ye = p1.y;
			break;
			/* last point */
		case 5:
			angle = a3;
			xe = p3.x;
			ye = p3.y;
			break;
		}
		/* determine if the extents are outside the arc */
		if (i < 4)
		{
			if (FP_GT(sweep, 0.0))
			{
				if (FP_LT(a3, a1))
				{
					if (FP_GT(angle, (a3 + 2 * M_PI)) || FP_LT(angle, a1)) continue;
				}
				else
				{
					if (FP_GT(angle, a3) || FP_LT(angle, a1)) continue;
				}
			}
			else
			{
				if (FP_GT(a3, a1))
				{
					if (FP_LT(angle, (a3 - 2 * M_PI)) || FP_GT(angle, a1)) continue;
				}
				else
				{
					if (FP_LT(angle, a3) || FP_GT(angle, a1)) continue;
				}
			}
		}

		LWDEBUGF(3, "lwcircle_calculate_gbox: potential extreame %d (%.16f, %.16f)", i, xe, ye);

		x1 = (FP_LT(x1, xe)) ? x1 : xe;
		y1 = (FP_LT(y1, ye)) ? y1 : ye;
		x2 = (FP_GT(x2, xe)) ? x2 : xe;
		y2 = (FP_GT(y2, ye)) ? y2 : ye;
	}

	LWDEBUGF(3, "lwcircle_calculate_gbox: extreames found (%.16f %.16f, %.16f %.16f)", x1, y1, x2, y2);

	z1 = FP_MIN(p1.z, p2.z);
	z1 = FP_MIN(z1, p3.z);
	z2 = FP_MAX(p1.z, p2.z);
	z2 = FP_MAX(z2, p3.z);
	
	m1 = FP_MIN(p1.m, p2.m);
	m1 = FP_MIN(m1, p3.m);
	m2 = FP_MAX(p1.m, p2.m);
	m2 = FP_MAX(m2, p3.m);

	gbox->xmin = x1;
	gbox->xmax = x2;
	gbox->ymin = y1;
	gbox->ymax = y2;
	
	if( FLAGS_GET_Z(gbox->flags) )
	{
		gbox->zmin = z1;
		gbox->zmax = z2;
	}
	if( FLAGS_GET_M(gbox->flags) )
	{
		gbox->mmin = m1;
		gbox->mmax = m2;
	}

	return G_SUCCESS;
}

static int ptarray_calculate_gbox( POINTARRAY *pa, GBOX *gbox )
{
	int i;
	POINT4D p;
	int has_z = FLAGS_GET_Z(gbox->flags);
	int has_m = FLAGS_GET_M(gbox->flags);
	
	if ( ! pa ) return G_FAILURE;
	if ( pa->npoints < 1 ) return G_FAILURE;
	
	getPoint4d_p(pa, 0, &p);
	gbox->xmin = gbox->xmax = p.x;
	gbox->ymin = gbox->ymax = p.y;
	if( has_z )
		gbox->zmin = gbox->zmax = p.z;
	if( has_m )
		gbox->mmin = gbox->mmax = p.m;
	
	for ( i = 1 ; i < pa->npoints; i++ )
	{
		getPoint4d_p(pa, i, &p);
		gbox->xmin = FP_MIN(gbox->xmin, p.x);
		gbox->xmax = FP_MAX(gbox->xmax, p.x);
		gbox->ymin = FP_MIN(gbox->ymin, p.y);
		gbox->ymax = FP_MAX(gbox->ymax, p.y);
		if( has_z )
		{
			gbox->zmin = FP_MIN(gbox->zmin, p.z);
			gbox->zmax = FP_MAX(gbox->zmax, p.z);
		}
		if( has_m )
		{
			gbox->mmin = FP_MIN(gbox->mmin, p.m);
			gbox->mmax = FP_MAX(gbox->mmax, p.m);
		}
	}
	return G_SUCCESS;
}

static int lwcircstring_calculate_gbox(LWCIRCSTRING *curve, GBOX *gbox)
{
	uchar flags = gflags(TYPE_HASZ(curve->type), TYPE_HASM(curve->type), 0);
	GBOX tmp;
	POINT4D p1, p2, p3;
	int i;
	
	if ( ! curve ) return G_FAILURE;
	if ( curve->points->npoints < 3 ) return G_FAILURE;

	tmp.flags = flags;
	
	/* Initialize */
	gbox->xmin = gbox->ymin = gbox->zmin = gbox->mmin = MAXFLOAT;
	gbox->xmax = gbox->ymax = gbox->zmax = gbox->mmax = -1 * MAXFLOAT;
	
	for ( i = 2; i < curve->points->npoints; i += 2 )
	{
		getPoint4d_p(curve->points, i-2, &p1);
		getPoint4d_p(curve->points, i-1, &p2);
		getPoint4d_p(curve->points, i, &p3);

		if (lwcircle_calculate_gbox(p1, p2, p3, &tmp) == G_FAILURE) 
			continue;

		gbox_merge(tmp, gbox);
	}
	
	return G_SUCCESS;
}

static int lwpoint_calculate_gbox(LWPOINT *point, GBOX *gbox)
{
	if ( ! point ) return G_FAILURE;
	return ptarray_calculate_gbox( point->point, gbox );
}

static int lwline_calculate_gbox(LWLINE *line, GBOX *gbox)
{
	if ( ! line ) return G_FAILURE;
	return ptarray_calculate_gbox( line->points, gbox );
}

static int lwpoly_calculate_gbox(LWPOLY *poly, GBOX *gbox)
{
	if ( ! poly ) return G_FAILURE;
	if ( poly->nrings == 0 ) return G_FAILURE;
	/* Just need to check outer ring */
	return ptarray_calculate_gbox( poly->rings[0], gbox );
}

static int lwcollection_calculate_gbox(LWCOLLECTION *coll, GBOX *gbox)
{
	GBOX subbox;
	int i;
	int result = G_FAILURE;
	int first = LW_TRUE;
	assert(coll);
	if( coll->ngeoms == 0 )
		return G_FAILURE;
	
	subbox.flags = gbox->flags;
	
	for( i = 0; i < coll->ngeoms; i++ )
	{
		if( lwgeom_calculate_gbox((LWGEOM*)(coll->geoms[i]), &subbox) == G_FAILURE )
		{
			continue;
		}
		else
		{
			if( first )
			{
				gbox_duplicate(subbox, gbox);
				first = LW_FALSE;
			}
			else
			{
				gbox_merge(subbox, gbox);
			}
			result = G_SUCCESS;
		}
	}
	return result;
}

int lwgeom_calculate_gbox(const LWGEOM *lwgeom, GBOX *gbox)
{
	if ( ! lwgeom ) return G_FAILURE;

	switch (TYPE_GETTYPE(lwgeom->type))
	{
	case POINTTYPE:
		return lwpoint_calculate_gbox((LWPOINT *)lwgeom, gbox);
	case LINETYPE:
		return lwline_calculate_gbox((LWLINE *)lwgeom, gbox);
	case CIRCSTRINGTYPE:
		return lwcircstring_calculate_gbox((LWCIRCSTRING *)lwgeom, gbox);
	case POLYGONTYPE:
		return lwpoly_calculate_gbox((LWPOLY *)lwgeom, gbox);
	case COMPOUNDTYPE:
	case CURVEPOLYTYPE:
	case MULTIPOINTTYPE:
	case MULTILINETYPE:
	case MULTICURVETYPE:
	case MULTIPOLYGONTYPE:
	case MULTISURFACETYPE:
	case COLLECTIONTYPE:
		return lwcollection_calculate_gbox((LWCOLLECTION *)lwgeom, gbox);
	}
	/* Never get here, please. */
	lwerror("unsupported type (%d)", TYPE_GETTYPE(lwgeom->type));
	return G_FAILURE;
}