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Revised set_bucket implementation.

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- sink some inline methods into the .cxx file
- add isValid test to SGBucket
- sgGetBuckets won't return invalid buckets near the poles
- additional unit tests
This commit is contained in:
James Turner 2014-02-13 12:36:06 +00:00
parent 748b13850a
commit 5fa0931a89
3 changed files with 165 additions and 112 deletions
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180
simgear/bucket/newbucket.cxx
View File

@ -27,17 +27,41 @@
# include <simgear_config.h>
#endif
#include <math.h>
#include <cmath>
#include <iostream>
#include <simgear/misc/sg_path.hxx>
#include <simgear/debug/logstream.hxx>
#include "newbucket.hxx"
// default constructor
SGBucket::SGBucket() {
SGBucket::SGBucket() :
lon(-1000),
lat(-1000),
x(0),
y(0)
{
}
bool SGBucket::isValid() const
{
// The most northerly valid latitude is 89, not 90. There is no tile
// whose *bottom* latitude is 90. Similar there is no tile whose left egde
// is 180 longitude.
return (lon >= -180) &&
(lon < 180) &&
(lat >= -90) &&
(lat < 90) &&
(x < 8) && (y < 8);
}
void SGBucket::make_bad()
{
lon = -1000;
lat = -1000;
}
// constructor for specified location
SGBucket::SGBucket(const double dlon, const double dlat) {
@ -45,18 +69,10 @@ SGBucket::SGBucket(const double dlon, const double dlat) {
}
SGBucket::SGBucket(const SGGeod& geod) {
set_bucket(geod);
set_bucket(geod.getLongitudeDeg(),
geod.getLatitudeDeg());
}
// create an impossible bucket if false
SGBucket::SGBucket(const bool is_good) {
set_bucket(0.0, 0.0);
if ( !is_good ) {
lon = -1000;
}
}
// Parse a unique scenery tile index and find the lon, lat, x, and y
SGBucket::SGBucket(const long int bindex) {
long int index = bindex;
@ -75,42 +91,49 @@ SGBucket::SGBucket(const long int bindex) {
x = index;
}
/* Calculate the greatest integral value less than
* or equal to the given value (floor(x)),
* but attribute coordinates close to the boundary to the next
* (increasing) integral
*/
static int floorWithEpsilon(double x)
{
double diff = x - static_cast<int>(x);
if ( (x >= 0.0) || (fabs(diff) < SG_EPSILON) ) {
return static_cast<int>(x);
} else {
return static_cast<int>(x) - 1;
}
}
// Set the bucket params for the specified lat and lon
void SGBucket::set_bucket( double dlon, double dlat ) {
void SGBucket::set_bucket( double dlon, double dlat )
{
if ((dlon < -180.0) || (dlon >= 180.0)) {
SG_LOG(SG_TERRAIN, SG_WARN, "SGBucket::set_bucket: passed longitude:" << dlon);
dlon = SGMiscd::normalizePeriodic(-180.0, 180.0, dlon);
}
if ((dlat < -90.0) || (dlat > 90.0)) {
SG_LOG(SG_TERRAIN, SG_WARN, "SGBucket::set_bucket: passed latitude" << dlat);
dlat = SGMiscd::clip(dlat, -90.0, 90.0);
}
//
// latitude first
// longitude first
//
double span = sg_bucket_span( dlat );
double diff = dlon - (double)(int)dlon;
// cout << "diff = " << diff << " span = " << span << endl;
/* Calculate the greatest integral longitude less than
* or equal to the given longitude (floor(dlon)),
* but attribute coordinates near the east border
* to the next tile.
*/
if ( (dlon >= 0) || (fabs(diff) < SG_EPSILON) ) {
lon = (int)dlon;
} else {
lon = (int)dlon - 1;
}
// we do NOT need to special case lon=180 here, since
// normalizePeriodic will never return 180; it will
// return -180, which is what we want.
lon = floorWithEpsilon(dlon);
// find subdivision or super lon if needed
if ( span < SG_EPSILON ) {
/* sg_bucket_span() never returns 0.0
* or anything near it, so this really
* should not occur at any time.
*/
// polar cap
lon = 0;
x = 0;
} else if ( span <= 1.0 ) {
if ( span <= 1.0 ) {
/* We have more than one tile per degree of
* longitude, so we need an x offset.
*/
x = (int)((dlon - lon) / span);
x = (int)((dlon - lon) / span);
} else {
/* We have one or more degrees per tile,
* so we need to find the base longitude
@ -123,45 +146,30 @@ void SGBucket::set_bucket( double dlon, double dlat ) {
*
* That way, the Greenwich Meridian is always
* a tile border.
*
* This gets us into trouble with the polar caps,
* which have width 360 and thus either span
* the range from 0 to 360 or from -360 to 0
* degrees, depending on whether lon is positive
* or negative!
*
* We also get into trouble with the 8 degree tiles
* north of 88N and south of 88S, because the west-
* and east-most tiles in that range will cover 184W
* to 176W and 176E to 184E respectively, with their
* center at 180E/W!
*/
lon=(int)floor(floor((lon+SG_EPSILON)/span)*span);
/* Correct the polar cap issue */
if ( lon < -180 ) {
lon = -180;
}
x = 0;
lon=static_cast<int>(floor(lon / span) * span);
x = 0;
}
//
// then latitude
//
diff = dlat - (double)(int)dlat;
/* Again, a modified floor() function (see longitude) */
if ( (dlat >= 0) || (fabs(diff) < SG_EPSILON) ) {
lat = (int)dlat;
lat = floorWithEpsilon(dlat);
// special case when passing in the north pole point (possibly due to
// clipping latitude above). Ensures we generate a valid bucket in this
// scenario
if (lat == 90) {
lat = 89;
y = 7;
} else {
lat = (int)dlat - 1;
/* Latitude base and offset are easier, as
* tiles always are 1/8 degree of latitude wide.
*/
y = (int)((dlat - lat) * 8);
}
/* Latitude base and offset are easier, as
* tiles always are 1/8 degree of latitude wide.
*/
y = (int)((dlat - lat) * 8);
}
void SGBucket::set_bucket(const SGGeod& geod)
{
set_bucket(geod.getLongitudeDeg(), geod.getLatitudeDeg());
@ -256,7 +264,18 @@ double SGBucket::get_height_m() const {
SGBucket SGBucket::sibling(int dx, int dy) const
{
if (!isValid()) {
SG_LOG(SG_TERRAIN, SG_WARN, "SGBucket::sibling: requesting sibling of invalid bucket");
return SGBucket();
}
double clat = get_center_lat() + dy * SG_BUCKET_SPAN;
// return invalid here instead of clipping, so callers can discard
// invalid buckets without having to check if it's an existing one
if ((clat < -90.0) || (clat > 90.0)) {
return SGBucket();
}
// find the lon span for the new latitude
double span = sg_bucket_span( clat );
@ -265,6 +284,15 @@ SGBucket SGBucket::sibling(int dx, int dy) const
return SGBucket(tmp, clat);
}
std::string SGBucket::gen_index_str() const
{
char tmp[20];
std::snprintf(tmp, 20, "%ld",
(((long)lon + 180) << 14) + ((lat + 90) << 6)
+ (y << 3) + x);
return (std::string)tmp;
}
// find the bucket which is offset by the specified tile units in the
// X & Y direction. We need the current lon and lat to resolve
// ambiguities when going from a wider tile to a narrower one above or
@ -354,8 +382,20 @@ void sgGetBuckets( const SGGeod& min, const SGGeod& max, std::vector<SGBucket>&
for (lat = min.getLatitudeDeg(); lat <= max.getLatitudeDeg(); lat += SG_BUCKET_SPAN) {
span = sg_bucket_span( lat );
for (lon = min.getLongitudeDeg(); lon <= max.getLongitudeDeg(); lon += span) {
list.push_back( SGBucket(lon , lat) );
for (lon = min.getLongitudeDeg(); lon <= max.getLongitudeDeg(); lon += span)
{
SGBucket b(lon, lat);
if (!b.isValid()) {
continue;
}
list.push_back(b);
}
}
}
std::ostream& operator<< ( std::ostream& out, const SGBucket& b )
{
return out << b.lon << ":" << (int)b.x << ", " << b.lat << ":" << (int)b.y;
}

46
simgear/bucket/newbucket.hxx
View File

@ -39,9 +39,8 @@
#include <simgear/math/SGMath.hxx>
#include <cmath>
#include <cstdio> // sprintf()
#include <ostream>
#include <string>
#include <iosfwd>
#include <vector>
/**
@ -99,16 +98,21 @@ class SGBucket {
private:
short lon; // longitude index (-180 to 179)
short lat; // latitude index (-90 to 89)
char x; // x subdivision (0 to 7)
char y; // y subdivision (0 to 7)
unsigned char x; // x subdivision (0 to 7)
unsigned char y; // y subdivision (0 to 7)
public:
/**
* Default constructor.
* Default constructor, creates an invalid SGBucket
*/
SGBucket();
/**
* Check if this bucket refers to a valid tile, or not.
*/
bool isValid() const;
/**
* Construct a bucket given a specific location.
* @param dlon longitude specified in degrees
@ -123,14 +127,6 @@ public:
*/
SGBucket(const SGGeod& geod);
/** Construct a bucket.
* @param is_good if false, create an invalid bucket. This is
* useful * if you are comparing cur_bucket to last_bucket and
* you want to * make sure last_bucket starts out as something
* impossible.
*/
SGBucket(const bool is_good);
/** Construct a bucket given a unique bucket index number.
* @param bindex unique bucket index
*/
@ -156,11 +152,8 @@ public:
* and you want to make sure last_bucket starts out as something
* impossible.
*/
inline void make_bad() {
set_bucket(0.0, 0.0);
lon = -1000;
}
void make_bad();
/**
* Generate the unique scenery tile index for this bucket
*
@ -185,14 +178,8 @@ public:
* string form.
* @return tile index in string form
*/
inline std::string gen_index_str() const {
char tmp[20];
std::sprintf(tmp, "%ld",
(((long)lon + 180) << 14) + ((lat + 90) << 6)
+ (y << 3) + x);
return (std::string)tmp;
}
std::string gen_index_str() const;
/**
* Build the base path name for this bucket.
* @return base path in string form
@ -335,12 +322,7 @@ void sgGetBuckets( const SGGeod& min, const SGGeod& max, std::vector<SGBucket>&
* @param out output stream
* @param b bucket
*/
inline std::ostream&
operator<< ( std::ostream& out, const SGBucket& b )
{
return out << b.lon << ":" << (int)b.x << ", " << b.lat << ":" << (int)b.y;
}
std::ostream& operator<< ( std::ostream& out, const SGBucket& b );
/**
* Compare two bucket structures for equality.

51
simgear/bucket/test_bucket.cxx
View File

@ -52,6 +52,7 @@ void testBasic()
COMPARE(b1.get_y(), 0);
COMPARE(b1.gen_index(), 3040320);
COMPARE(b1.gen_base_path(), "e000n50/e005n55");
VERIFY(b1.isValid());
SGBucket b2(-10.1, -43.8);
COMPARE(b2.get_chunk_lon(), -11);
@ -59,6 +60,7 @@ void testBasic()
COMPARE(b2.get_x(), 3);
COMPARE(b2.get_y(), 1); // latitude chunks numbered bottom to top, it seems
COMPARE(b2.gen_base_path(), "w020s50/w011s44");
VERIFY(b2.isValid());
SGBucket b3(123.48, 9.01);
COMPARE(b3.get_chunk_lon(), 123);
@ -66,7 +68,37 @@ void testBasic()
COMPARE(b3.get_x(), 3);
COMPARE(b3.get_y(), 0);
COMPARE(b3.gen_base_path(), "e120n00/e123n09");
VERIFY(b3.isValid());
SGBucket defBuck;
VERIFY(!defBuck.isValid());
b3.make_bad();
VERIFY(!b3.isValid());
SGBucket atAntiMeridian(180.0, 12.3);
VERIFY(atAntiMeridian.isValid());
COMPARE(atAntiMeridian.get_chunk_lon(), -180);
COMPARE(atAntiMeridian.get_x(), 0);
SGBucket atAntiMeridian2(-180.0, -78.1);
VERIFY(atAntiMeridian2.isValid());
COMPARE(atAntiMeridian2.get_chunk_lon(), -180);
COMPARE(atAntiMeridian2.get_x(), 0);
// check comparisom operator overload
SGBucket b4(5.11, 55.1);
VERIFY(b1 == b4); // should be equal
VERIFY(b1 == b1);
VERIFY(b1 != defBuck);
VERIFY(b1 != b2);
// check wrapping/clipping of inputs
SGBucket wrapMeridian(-200.0, 45.0);
COMPARE(wrapMeridian.get_chunk_lon(), 160);
SGBucket clipPole(48.9, 91);
COMPARE(clipPole.get_chunk_lat(), 89);
}
void testPolar()
@ -78,6 +110,11 @@ void testPolar()
COMPARE(b1.get_x(), 0);
COMPARE(b1.get_y(), 7);
COMPARE(b2.get_chunk_lat(), 89);
COMPARE(b2.get_chunk_lon(), 0);
COMPARE(b2.get_x(), 0);
COMPARE(b2.get_y(), 7);
COMPARE(b1.gen_index(), b2.gen_index());
SGGeod actualNorthPole1 = b1.get_corner(2);
@ -108,9 +145,8 @@ void testPolar()
COMPARE_EP(actualSouthPole2.getLatitudeDeg(), -90.0);
COMPARE_EP(actualSouthPole2.getLongitudeDeg(), -168);
// no automatic wrapping of these values occurs
SGBucket b7(200, 89.88);
COMPARE(b7.get_chunk_lon(), 192);
COMPARE(b7.get_chunk_lon(), -168);
}
@ -198,16 +234,11 @@ void testPolarOffset()
COMPARE(b6.gen_index(), sgBucketOffset(177, 87.3, 1, 1));
#if 0
// offset vertically towards the pole
SGBucket b3(b1.sibling(0, -5));
COMPARE(b3.get_chunk_lat(), -90);
COMPARE(b3.get_chunk_lon(), -12);
COMPARE(b3.get_x(), 0);
COMPARE(b3.get_y(), 0);
SGBucket b7(b1.sibling(0, -5));
VERIFY(!b7.isValid());
COMPARE(b3.gen_index(), sgBucketOffset(-11.7, -89.6, 0, 0));
#endif
VERIFY(!SGBucket(0, 90).sibling(0, 1).isValid());
}
// test behaviour of bucket-offset near the anti-meridian (180-meridian)