SkyMesh Class Reference

#include <skymesh.h>

Inheritance diagram for SkyMesh:

Public Member Functions
void	aperture (SkyPoint *center, double radius, MeshBufNum_t bufNum=DRAW_BUF)
int	debug () const
void	debug (int debug)
void	draw (QPainter &psky, MeshBufNum_t bufNum=DRAW_BUF)
DrawID	drawID () const
int	incDrawID ()
Trixel	index (const SkyPoint *p)
bool	inDraw () const
void	inDraw (bool inDraw)
const SkyRegion &	skyRegion (const SkyPoint &p1, const SkyPoint &p2)
Stars and CLines
Routines used for indexing stars and CLines. The following four routines are used for indexing stars and CLines. They differ from the normal routines because they take proper motion into account while the normal routines always index the J2000 position. Since the proper motion depends on time, it is essential to call setKSNumbers to set the time before doing the indexing. The default value is J2000.
void	setKSNumbers (KSNumbers *num)
Trixel	indexStar (StarObject *star)
void	indexStar (StarObject *star1, StarObject *star2)
const IndexHash &	indexStarLine (SkyList *points)
Multi Shape Index Routines
The first two routines use QPoint and the rest use SkyPoint
void	index (const QPointF &p1, const QPointF &p2, const QPointF &p3)
void	index (const QPointF &p1, const QPointF &p2, const QPointF &p3, const QPointF &p4)
void	index (const SkyPoint *center, double radius, MeshBufNum_t bufNum=DRAW_BUF, const bool useJ2000=true)
void	index (const SkyPoint *p1, const SkyPoint *p2)
void	index (const SkyPoint *p1, const SkyPoint *p2, const SkyPoint *p3)
void	index (const SkyPoint *p1, const SkyPoint *p2, const SkyPoint *p3, const SkyPoint *p4)
IndexHash Routines
The follow routines are used to index SkyList data structures. They fill a QHash with the indices of the trixels that cover the data structure. These are all used as callbacks in the LineListIndex subclasses so they can use the same indexing code to index different data structures. See also indexStarLine() above.
const IndexHash &	indexLine (SkyList *points)
const IndexHash &	indexLine (SkyList *points, IndexHash *skip)
const IndexHash &	indexPoly (SkyList *points)
const IndexHash &	indexPoly (const QPolygonF *points)
Public Member Functions inherited from HTMesh
	HTMesh (int level, int buildLevel, int numBuffers=1)
Trixel	index (double ra, double dec) const
void	intersect (double ra, double dec, double radius, BufNum bufNum=0)
void	intersect (double ra1, double dec1, double ra2, double dec2, BufNum bufNum=0)
void	intersect (double ra1, double dec1, double ra2, double dec2, double ra3, double dec3, BufNum bufNum=0)
void	intersect (double ra1, double dec1, double ra2, double dec2, double ra3, double dec3, double ra4, double dec4, BufNum bufNum=0)
int	intersectSize (BufNum bufNum=0)
int	level () const
MeshBuffer *	meshBuffer (BufNum bufNum=0)
void	setDebug (int debug)
int	size () const
void	vertices (Trixel id, double *ra1, double *dec1, double *ra2, double *dec2, double *ra3, double *dec3)

Static Public Member Functions
static SkyMesh *	Create (int level)
static SkyMesh *	Instance ()
static SkyMesh *	Instance (int level)

Protected Member Functions
	SkyMesh (int level)
	SkyMesh (SkyMesh &skyMesh)

Detailed Description

Provides an interface to the Hierarchical Triangular Mesh (HTM) library written by A.

Szalay, John Doug Reynolds, Jim Gray, and Peter Z. Kunszt.

HTM divides the celestial sphere up into little triangles (trixels) and gives each triangle a unique integer id. We index objects by putting a pointer to the object in a data structure accessible by the id number, for example QList<QList<StarObject*> or QHash<int, QList<LineListComponent*>.

Use aperture(centerPoint, radius) to get a list of trixels visible in the circle. Then use a MeshIterator to iterate over the indices of the visible trixels. Look up each index in the top level QHash or QList data structure and the union of all the elements of the QList's returned will contain all the objects visible in the circle in the sky specified in the aperture() call.

The drawID is used for extended objects that may be covered by more than one trixel. Every time aperture() is called, drawID is incremented by one. Extended objects should each contain their own drawID. If an object's drawID is the same as the current drawID then it shouldn't be drawn again because it was already drawn in this draw cycle. If the drawID is different then it should be drawn and then the drawID should be set to the current drawID() so it doesn't get drawn again this cycle.

The list of visible trixels found from an aperture() call or one of the primitive index() by creating a new MeshIterator instance:

 MeshIterator( HTMesh *mesh )

The MeshIterator has its own bool hasNext(), int next(), and int size() methods for iterating through the integer indices of the found trixels or for just getting the total number of found trixels.

Definition at line 73 of file skymesh.h.

Constructor & Destructor Documentation

SkyMesh()

SkyMesh::SkyMesh ( int level )

protected

Definition at line 49 of file skymesh.cpp.

Member Function Documentation

aperture()

void SkyMesh::aperture	(	SkyPoint *	center,
		double	radius,
		MeshBufNum_t	bufNum = DRAW_BUF )

finds the set of trixels that cover the circular aperture specified after first performing a reverse precession correction on the center so we don't have to re-index objects simply due to precession.

The drawID also gets incremented which is useful for drawing extended objects. Typically a safety factor of about one degree is added to the radius to account for proper motion, refraction and other imperfections.

Parameters

center	Center of the aperture
radius	Radius of the aperture in degrees
bufNum	Buffer to use

Note

See HTMesh.h for more

Definition at line 56 of file skymesh.cpp.

Create()

SkyMesh * SkyMesh::Create ( int level )

static

creates the single instance of SkyMesh.

The level indicates how fine a mesh we will use. The number of triangles (trixels) in the mesh will be 8 * 4^level so a mesh of level 5 will have 8 * 4^5 = 8 * 2^10 = 8192 trixels. The size of the triangles are roughly pi / * 2^(level + 1) so a level 5 mesh will have triangles size roughly of .05 radians or 2.8 degrees.

Definition at line 25 of file skymesh.cpp.

debug() [1/2]

int SkyMesh::debug ( ) const

inline

Returns the debug level.

This is used as a global debug level for LineListIndex and its subclasses.

Definition at line 256 of file skymesh.h.

debug() [2/2]

void SkyMesh::debug ( int debug )

inline

Sets the debug level.

Definition at line 260 of file skymesh.h.

draw()

void SkyMesh::draw	(	QPainter &	psky,
		MeshBufNum_t	bufNum = DRAW_BUF )

Draws the outline of all the trixels in the specified buffer.

This was very useful during debugging. I don't precess the points because I mainly use it with the IN_CONSTELL_BUF which is not precessed. We will probably have buffers serve double and triple duty in the production code to save space in which case this function may become less useful.

Definition at line 276 of file skymesh.cpp.

drawID()

DrawID SkyMesh::drawID ( ) const

inline

Returns

the current drawID which gets incremented each time aperture() is called.

Definition at line 265 of file skymesh.h.

incDrawID()

int SkyMesh::incDrawID ( )

inline

increments the drawID and returns the new value.

This is useful when you want to use the drawID to ensure you are not repeating yourself when iterating over the elements of an IndexHash. It is currently used in LineListIndex::reindex().

Definition at line 272 of file skymesh.h.

index() [1/7]

void SkyMesh::index	(	const QPointF &	p1,
		const QPointF &	p2,
		const QPointF &	p3 )

finds the indices of the trixels that cover the triangle specified by the three QPointF's.

Definition at line 116 of file skymesh.cpp.

index() [2/7]

void SkyMesh::index	(	const QPointF &	p1,
		const QPointF &	p2,
		const QPointF &	p3,
		const QPointF &	p4 )

Finds the trixels needed to cover the quadrilateral specified by the four QPointF's.

Definition at line 121 of file skymesh.cpp.

index() [3/7]

void SkyMesh::index	(	const SkyPoint *	center,
		double	radius,
		MeshBufNum_t	bufNum = DRAW_BUF,
		const bool	useJ2000 = true )

finds the indices of the trixels covering the circle specified by center and radius.

Parameters

useJ2000

if set to false, the method uses ra() and dec() instead

Definition at line 94 of file skymesh.cpp.

index() [4/7]

Trixel SkyMesh::index

(

const SkyPoint *

p

)

returns the index of the trixel containing p.

Definition at line 74 of file skymesh.cpp.

index() [5/7]

void SkyMesh::index	(	const SkyPoint *	p1,
		const SkyPoint *	p2 )

finds the indices of the trixels covering the line segment connecting p1 and p2.

Definition at line 99 of file skymesh.cpp.

index() [6/7]

void SkyMesh::index	(	const SkyPoint *	p1,
		const SkyPoint *	p2,
		const SkyPoint *	p3 )

finds the indices of the trixels covering the triangle specified by vertices: p1, p2, and p3.

Definition at line 104 of file skymesh.cpp.

index() [7/7]

void SkyMesh::index	(	const SkyPoint *	p1,
		const SkyPoint *	p2,
		const SkyPoint *	p3,
		const SkyPoint *	p4 )

finds the indices of the trixels covering the quadralateral specified by the vertices: p1, p2, p3, and p4.

Definition at line 110 of file skymesh.cpp.

indexLine() [1/2]

const IndexHash & SkyMesh::indexLine

(

SkyList *

points

)

fills a QHash with the trixel indices needed to cover all the line segments specified in the QVector<SkyPoints*> points.

Parameters

points

the points of the line segment. The debug mode causes extra info to be printed.

Definition at line 126 of file skymesh.cpp.

indexLine() [2/2]

const IndexHash & SkyMesh::indexLine	(	SkyList *	points,
		IndexHash *	skip )

as above but allows for skipping the indexing of some of the points.

Parameters

points	the line segment to be indexed.
skip	a hash indicating which points to skip debugging info.

Definition at line 157 of file skymesh.cpp.

indexPoly() [1/2]

const IndexHash & SkyMesh::indexPoly

(

const QPolygonF *

points

)

does the same as above but with a QPolygonF as the container for the points.

Definition at line 240 of file skymesh.cpp.

indexPoly() [2/2]

const IndexHash & SkyMesh::indexPoly

(

SkyList *

points

)

fills a QHash with the trixel indices needed to cover the polygon specified in the QList<SkyPoints*> points.

There is no version with a skip parameter because it does not make sense to skip some of the edges of a filled polygon.

Parameters

points

the points of the line segment. The debug mode causes extra info to be printed.

Definition at line 208 of file skymesh.cpp.

indexStar() [1/2]

Trixel SkyMesh::indexStar

(

StarObject *

star

)

returns the trixel that contains the star at the set time with proper motion taken into account but not precession.

This is a feature not a bug.

Definition at line 79 of file skymesh.cpp.

indexStar() [2/2]

void SkyMesh::indexStar	(	StarObject *	star1,
		StarObject *	star2 )

fills the default buffer with all the trixels needed to cover the line connecting the two stars.

Definition at line 86 of file skymesh.cpp.

indexStarLine()

const IndexHash & SkyMesh::indexStarLine

(

SkyList *

points

)

Fills a hash with all the trixels needed to cover all the line segments in the SkyList where each SkyPoint is assumed to be a star and proper motion is taken into account.

Used only by ConstellationsLines.

Definition at line 131 of file skymesh.cpp.

inDraw() [1/2]

bool SkyMesh::inDraw ( ) const

inline

Definition at line 283 of file skymesh.h.

inDraw() [2/2]

void SkyMesh::inDraw ( bool inDraw )

inline

Definition at line 284 of file skymesh.h.

Instance() [1/2]

SkyMesh * SkyMesh::Instance ( )

static

returns the default instance of SkyMesh or null if it has not yet been created.

Definition at line 39 of file skymesh.cpp.

Instance() [2/2]

SkyMesh * SkyMesh::Instance ( int level )

static

returns the instance of SkyMesh corresponding to the given level

Returns

the instance of SkyMesh at the given level, or nullptr if it has not yet been created.

Definition at line 44 of file skymesh.cpp.

setKSNumbers()

void SkyMesh::setKSNumbers ( KSNumbers * num )

inline

sets the time for indexing StarObjects and CLines.

Definition at line 145 of file skymesh.h.

skyRegion()

const SkyRegion & SkyMesh::skyRegion	(	const SkyPoint &	p1,
		const SkyPoint &	p2 )

returns the sky region needed to cover the rectangle defined by two SkyPoints p1 and p2

Parameters

p1	top-left SkyPoint of the rectangle
p2	bottom-right SkyPoint of the rectangle

Definition at line 312 of file skymesh.cpp.

---

The documentation for this class was generated from the following files:

• skymesh.h
• skymesh.cpp