sky::SkyDome Class Reference

Sky dome. More...

#include <_src_sky_sky_dome.hh>

List of all members.

Public Member Functions
virtual fp	GetRadius (void)
virtual NodeSort	GetNodeSort (void)
WorldVertex	ComputeVertexOnDome (const Degree lat, const Degree lon, const fp radiusScale)
uint	GetPointCount (void)
void	SetColor (const RGBA color, const Degree lat, const Degree lon)
void	SetColor (const RGBA color, const uint flatIdx)
void	SetColorAll (const RGBA color)
RGBA	GetColor (const Degree lat, const Degree lon)
uint	GetSliceCount (void) const
bool	IfInside (const WorldVertex &pos, const fp radius)
Private Member Functions
	SkyDome (const WorldVertex &center, const fp radius, const RGBA color, const int sliceCount)
virtual	~SkyDome ()
void	SetColor_ (const RGBA color, const pair< int, int > idx)
pair< int, int >	Deg2Idx (const Degree lat, const Degree lon)
Point &	GetPoint (const pair< int, int > idx)
Patch &	GetPatch (const pair< int, int > idx)
void	JoinPointAndPatch (const int pointLat, const int pointLon, const int patchLat, const int patchLon)
Private Attributes
fp	mRadius
	HIDES Object::mRadius (ok, better than mDomeRadius).
RGBA	mColor
	default color
const int	mLatSliceCount
	latitude slices
const int	mLonSliceCount
	longitude slices
Array2D< Point >	mPoints
	vertexs on dome (rely on Array2D clamping indexs)
Array2D< Patch >	mPatches
	primitives of dome
const Degree	mLatLimit
	latitudes beyond this won't be drawn
Friends
class	shptr< SkyDome >
class	Sky
class	Point
class	Patch
Classes
class	Patch
	Defines a quad of sky-dome. More...
class	Point
	Defines one vertex on dome which will be shared by multiple Patches. Using an index, rather than a ptr, avoids the invalid iterator pitfall. More...

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Detailed Description

Sky dome.

Latitude vs. longitude: ----------------------- Latitude defines a half-circle {0',...,180'}. Longitude defines a full-circle {0',...,360'}.

SkyDome vs. SkyDomePainter: --------------------------- SkyDome is a general data container (in terms of vertex colors). Algorithms to paint the sky are innately specific, so they're separated as the SkyDomePainter class. This separation would allow painting an Earth or Martian sky using different SkyDomePainter implementations.

Implementation of the sky dome: ------------------------------- The construction of the sky dome accords with the requirement that a 2D (lat,lon) coordinate has to be correlated to a 3D vertex, and also to OSG nodes in order to modify a vertex's color.

The first phase is a multi-level loop that computes vertexs of a ring on the dome where a latitude indexes a ring, and a longitude indexes a vertex in the ring. The OSG nodes for a vertex on the dome is collected into the SkyDome::Point class, and points are organized as a 2D array.

The second phase builds graphics primitives for each patch of the dome. Imagine the dome divided into horizontal bands (two connected rings), then each band is divided into quads.

When a client (SkyDomePainter) requests to change a color by (lat,lon), SkyDome does a lookup into the 2D array of Points. Note that one Point will be shared by multiple quads, each having its own color array, so more than one color array (etc) must be updated for a color modification. Therefore, the OSG nodes for a patch of the dome is defined by the class Patch, and a Point will have multiple references to a Patch.

Edge-cases (implementation): ---------------------------- The 2D array of Points is plus one. lon=0 and lon=360 reference different vertexs. A bad design would be to require the client to make two calls (worse, 360 is technically an overrun case). SetColor( color, lat=0, lon=0 ); SetColor( color, lat=0, lon=360 ); The implementation, as a special-case, will automatically change both vertexs if lon is almost equal to 0.0 or 360.0.

Problems: --------- Increasing sky dome will affect the view frustum. If its radius is too large, frustum clipping will occur.

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Constructor & Destructor Documentation

sky::SkyDome::SkyDome	(	const WorldVertex &	center,
		const fp	radius,
		const RGBA	color,
		const int	sliceCount
	)			[private]

sky::SkyDome::~SkyDome

(

)

[private, virtual]

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Member Function Documentation

virtual fp sky::SkyDome::GetRadius

(

void

)

[inline, virtual]

NodeSort sky::SkyDome::GetNodeSort

(

void

)

[virtual]

For scene-graph to render optimally, nodes should be sorted by state.

WorldVertex sky::SkyDome::ComputeVertexOnDome	(	const Degree	lat,
		const Degree	lon,
		const fp	radiusScale
	)

This lets a client compute a 3D world vertex on the sky dome. For visibility from the inside of the dome, pass a value such as 0.95f in radiusScale.

uint sky::SkyDome::GetPointCount

(

void

)

[inline]

void sky::SkyDome::SetColor	(	const RGBA	color,
		const Degree	lat,
		const Degree	lon
	)

void sky::SkyDome::SetColor	(	const RGBA	color,
		const uint	flatIdx
	)

void sky::SkyDome::SetColorAll

(

const RGBA

color

)

RGBA sky::SkyDome::GetColor	(	const Degree	lat,
		const Degree	lon
	)

Get the color of a vertex on the dome. This finds the vertex nearest the (lat,lon) coordinates.

uint sky::SkyDome::GetSliceCount

(

void

)

const [inline]

bool sky::SkyDome::IfInside	(	const WorldVertex &	pos,
		const fp	radius
	)

Returns:

True if position+radius is inside sky dome.

void sky::SkyDome::SetColor_	(	const RGBA	color,
		const pair< int, int >	idx
	)			[private]

pair<int,int> sky::SkyDome::Deg2Idx	(	const Degree	lat,
		const Degree	lon
	)			[inline, private]

Point& sky::SkyDome::GetPoint

(

const pair< int, int >

idx

)

[inline, private]

Patch& sky::SkyDome::GetPatch

(

const pair< int, int >

idx

)

[inline, private]

void sky::SkyDome::JoinPointAndPatch	(	const int	pointLat,
		const int	pointLon,
		const int	patchLat,
		const int	patchLon
	)			[inline, private]

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Friends And Related Function Documentation

friend class shptr< SkyDome > [friend]

friend class Sky [friend]

friend class Point [friend]

friend class Patch [friend]

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Member Data Documentation

fp sky::SkyDome::mRadius [private]

HIDES Object::mRadius (ok, better than mDomeRadius).

RGBA sky::SkyDome::mColor [private]

default color

const int sky::SkyDome::mLatSliceCount [private]

latitude slices

const int sky::SkyDome::mLonSliceCount [private]

longitude slices

Array2D<Point> sky::SkyDome::mPoints [private]

vertexs on dome (rely on Array2D clamping indexs)

Array2D<Patch> sky::SkyDome::mPatches [private]

primitives of dome

const Degree sky::SkyDome::mLatLimit [private]

latitudes beyond this won't be drawn

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

• _src_sky_sky_dome.hh
• _src_sky_sky_dome.cc