sphere

Documentation

Overview

Package sphere contains convenience methods for generating coordinates on a sphere. All angles are measured in degrees.

Index

• Variables
• type T
  • func (t T) Circle(center kml.Coordinate, radius, maxErr float64) []kml.Coordinate
  • func (t T) HaversineDistance(c1, c2 kml.Coordinate) float64
  • func (t T) Offset(origin kml.Coordinate, distance, bearing float64) kml.Coordinate

Examples

• T.Circle

Variables

var (
	// Unit is the unit sphere.
	Unit = T{R: 1}

	// FAI is the FAI sphere, measured in meters.
	FAI = T{R: 6371000}

	// WGS84 is a sphere whose radius is equal to the the semi-major axis of
	// the WGS84 ellipsoid, measured in meters.
	WGS84 = T{R: 6378137}
)

Types

type T

type T struct {
	R float64
}

A T is a sphere of radius R.

func (T) Circle

func (t T) Circle(center kml.Coordinate, radius, maxErr float64) []kml.Coordinate

Circle returns an array of kml.Coordinates that approximate a circle of radius radius centered on center with a maximum error of maxErr.

Example

k := kml.KML(
	kml.Placemark(
		kml.LineString(
			kml.Coordinates(WGS84.Circle(kml.Coordinate{Lon: 7.658320, Lat: 45.97651, Alt: 0}, 5500, 1)...),
		),
	),
)
if err := k.WriteIndent(os.Stdout, "", "  "); err != nil {
	log.Fatal(err)
}

Output:

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
  <Placemark>
    <LineString>
      <coordinates>7.658320000000001,46.02591734062657 7.662139516168806,46.02584604997079 7.665947990217271,46.02563238410356 7.669734412203183,46.02527696072462 7.6734878364438375,46.024780807333265 7.677197413404282,46.024145358234385 7.680852421296631,46.02337245035928 7.684442297295684,46.02246431791424 7.68795666827733,46.02142358587259 7.691385380987812,46.02025326232997 7.694718531553885,46.01895672974565 7.697946494246017,46.01753773509616 7.701059949409304,46.016000378970816 7.704049910479545,46.01434910364147 7.706907750004893,46.01258868014259 7.70962522459679,46.010724194399664 7.712194498737385,46.00876103244779 7.71460816737436,46.00670486478404 7.7168592772379965,46.004561629900266 7.7189413468194505,46.00233751704516 7.720848384953432,46.00003894826663 7.722574907953002,45.99767255978747 7.72411595524867,45.995245182769374 7.7254671034887545,45.99276382352193 7.726624479062679,45.99023564321468 7.727584769013816,45.987667937151684 7.728345230313356,45.98506811366952 7.728903697471718,45.982443672719974 7.729258588468999,45.97980218420011 7.729408908990993,45.97715126609252 7.729354254962322,45.97449856247933 7.7290948133732424,45.971851721493394 7.728631361401627,45.96921837327061 7.727965263836586,45.9666061079666 7.727098468814982,45.964022453901094 7.726033501886931,45.961474855892696 7.724773458431034,45.958970653845924 7.723321994444677,45.95651706165177 7.72168331573922,45.95412114646181 7.719862165574228,45.95178980839473 7.717863810769134,45.94952976073298 7.715694026334803,45.947347510665324 7.713359078671356,45.94524934063003 7.710865707382437,45.94324129031095 7.708221105759674,45.941329139337306 7.705432899994549,45.93951839073578 7.702509127178112,45.9378142551811 7.69945821215212,45.93622163608952 7.696288943278037,45.934745115596385 7.693010447193027,45.93338894145731 7.689632162624654,45.932157014909166 7.686163813338272,45.93105287952481 7.682615380293243,45.93007971109241 7.678997073086062,45.92924030854741 7.675319300760165,45.92853708598244 7.671592642063786,45.9279720657571 7.667827815238496,45.92754687272685 7.66403564742224,45.927262729606845 7.660227043751559,45.92712045348346 7.656412956248442,45.92712045348346 7.652604352577761,45.927262729606845 7.648812184761505,45.92754687272685 7.645047357936216,45.9279720657571 7.641320699239836,45.92853708598244 7.637642926913938,45.92924030854741 7.634024619706757,45.93007971109241 7.630476186661729,45.93105287952481 7.627007837375347,45.932157014909166 7.623629552806974,45.93338894145731 7.620351056721964,45.934745115596385 7.617181787847882,45.93622163608952 7.61413087282189,45.9378142551811 7.611207100005451,45.93951839073578 7.608418894240327,45.941329139337306 7.605774292617563,45.94324129031095 7.603280921328645,45.94524934063003 7.600945973665198,45.947347510665324 7.598776189230867,45.94952976073298 7.596777834425772,45.95178980839473 7.59495668426078,45.95412114646181 7.593318005555323,45.95651706165177 7.591866541568967,45.958970653845924 7.590606498113069,45.961474855892696 7.589541531185019,45.964022453901094 7.588674736163415,45.9666061079666 7.588008638598374,45.96921837327061 7.587545186626759,45.971851721493394 7.587285745037679,45.97449856247933 7.5872310910090075,45.97715126609252 7.587381411531002,45.97980218420011 7.587736302528283,45.982443672719974 7.5882947696866445,45.98506811366952 7.589055230986185,45.987667937151684 7.590015520937322,45.99023564321468 7.591172896511246,45.99276382352193 7.592524044751331,45.995245182769374 7.594065092046999,45.99767255978747 7.5957916150465685,46.00003894826663 7.597698653180551,46.00233751704516 7.599780722762004,46.004561629900266 7.6020318326256415,46.00670486478404 7.604445501262616,46.00876103244779 7.607014775403211,46.010724194399664 7.6097322499951074,46.01258868014259 7.612590089520457,46.01434910364147 7.6155800505906965,46.016000378970816 7.618693505753984,46.01753773509616 7.621921468446115,46.01895672974565 7.625254619012189,46.02025326232997 7.628683331722671,46.02142358587259 7.632197702704317,46.02246431791424 7.63578757870337,46.02337245035928 7.63944258659572,46.024145358234385 7.643152163556164,46.024780807333265 7.646905587796819,46.02527696072462 7.65069200978273,46.02563238410356 7.654500483831195,46.02584604997079 7.658320000000001,46.02591734062657</coordinates>
    </LineString>
  </Placemark>
</kml>

func (T) HaversineDistance

func (t T) HaversineDistance(c1, c2 kml.Coordinate) float64

HaversineDistance returns the great circle distance beween c1 and c2 using the Haversine formula. Altitude is ignored.

func (T) Offset

func (t T) Offset(origin kml.Coordinate, distance, bearing float64) kml.Coordinate

Offset returns the coordinate at distance from origin in direction bearing.