A node in a quad tree used to store a patch of terrain. More...

#include <OgreTerrainQuadTreeNode.h>

Inheritance diagram for Ogre::TerrainQuadTreeNode:

Classes
struct	LodLevel

Public Types
typedef std::vector< LodLevel * >	LodLevelList

Public Member Functions
	TerrainQuadTreeNode (Terrain terrain, TerrainQuadTreeNode parent, uint16 xoff, uint16 yoff, uint16 size, uint16 lod, uint16 depth)
	Constructor.

virtual	~TerrainQuadTreeNode ()

void	assignVertexData (uint16 treeDepthStart, uint16 treeDepthEnd, uint16 resolution, uint sz)
	Assign vertex data to the tree, from a depth and at a given resolution.

bool	calculateCurrentLod (const Camera *cam, Real cFactor)
	Calculate appropriate LOD for this node and children.

void	finaliseDeltaValues (const Rect &rect)
	Promote the delta values calculated to the runtime ones (this must be called in the main thread).

uint16	getBaseLod () const
	Get the base LOD level this node starts at (the highest LOD it handles)

const AxisAlignedBox &	getBoundingBox (void) const override
	Get the AABB (local coords) of this node.

Real	getBoundingRadius () const override
	Get the bounding radius of this node.

TerrainQuadTreeNode *	getChild (unsigned short child) const
	Get child node.

int	getCurrentLod () const
	Get the current LOD index (only valid after calculateCurrentLod)

const Vector3 &	getLocalCentre () const
	Get the local centre of this node, relative to parent terrain centre.

uint16	getLodCount () const
	Get the number of LOD levels this node can represent itself (only > 1 for leaf nodes)

const LodLevel *	getLodLevel (uint16 lod)
	Get the LodLevel information for a given lod.

float	getLodTransition () const
	Get the transition state between the current LOD and the next lower one (only valid after calculateCurrentLod)

Real	getMaxHeight () const
	Get the maximum height of the node.

Real	getMinHeight () const
	Get the minimum height of the node.

TerrainQuadTreeNode *	getParent () const
	Get parent node.

Terrain *	getTerrain () const
	Get ultimate parent terrain.

uint16	getXOffset () const
	Get the horizontal offset into the main terrain data of this node.

uint16	getYOffset () const
	Get the vertical offset into the main terrain data of this node.

bool	isLeaf () const
	Is this a leaf node (no children)

bool	isRenderedAtCurrentLod () const
	Returns whether this node is rendering itself at the current LOD level.

bool	isSelfOrChildRenderedAtCurrentLod () const
	Returns whether this node or its children are being rendered at the current LOD level.

void	load ()
	Load node and children (perform GPU tasks, will be render thread)

void	load (uint16 depthStart, uint16 depthEnd)
	Load node and children in a depth range (perform GPU tasks, will be render thread)

void	loadSelf ()

void	mergeIntoBounds (long x, long y, const Vector3 &pos)
	Merge a point (relative to terrain node) into the local bounds, and that of children if applicable.

void	notifyDelta (uint16 x, uint16 y, uint16 lod, Real delta)
	Notify the node (and children) of a height delta value.

bool	pointIntersectsNode (long x, long y)
	Returns true if the given point is in the terrain area that this node references.

void	postDeltaCalculation (const Rect &rect)
	Notify the node (and children) that deltas have finished being calculated.

void	preDeltaCalculation (const Rect &rect)
	Notify the node (and children) that deltas are going to be calculated for a given range.

void	prepare ()
	Prepare node and children (perform CPU tasks, may be background thread)

void	prepare (StreamSerialiser &stream)
	Prepare node from a stream.

bool	rectContainsNode (const Rect &rect)
	Returns true if the given rectangle completely contains the terrain area that this node references.

bool	rectIntersectsNode (const Rect &rect)
	Returns true if the given rectangle overlaps the terrain area that this node references.

void	resetBounds (const Rect &rect)
	Reset the bounds of this node and all its children for the region given.

void	save (StreamSerialiser &stream)
	Save node to a stream.

void	setCurrentLod (int lod)
	Manually set the current LOD, intended for internal use only.

void	setLodTransition (float t)
	Manually set the current LOD transition state, intended for internal use only.

void	unload ()
	Unload node and children (perform GPU tasks, will be render thread)

void	unload (uint16 depthStart, uint16 depthEnd)
	Unload node and children in a depth range (perform GPU tasks, will be render thread)

void	unprepare ()
	Unprepare node and children (perform CPU tasks, may be background thread)

void	updateVertexData (bool positions, bool deltas, const Rect &rect, bool cpuData)
	Tell the node to update its vertex data for a given region.

void	useAncestorVertexData (TerrainQuadTreeNode *owner, uint16 treeDepthEnd, uint16 resolution)
	Tell a node that it should use an anscestor's vertex data.

Static Public Attributes
static unsigned short	DELTA_BUFFER
	Buffer binding used for holding delta values.

static unsigned short	POSITION_BUFFER
	Buffer binding used for holding positions.

Detailed Description

A node in a quad tree used to store a patch of terrain.

Algorithm overview:

: Our goal is to perform traditional chunked LOD with geomorphing. But, instead of just dividing the terrain into tiles, we will divide them into a hierarchy of tiles, a quadtree, where any level of the quadtree can be a rendered tile (to the exclusion of its children). The idea is to collect together children into a larger batch with their siblings as LOD decreases, to improve performance.

: The minBatchSize and maxBatchSize parameters on Terrain a key to defining this behaviour. Both values are expressed in vertices down one axis. maxBatchSize determines the number of tiles on one side of the terrain, which is numTiles = (terrainSize-1) / (maxBatchSize-1). This in turn determines the depth of the quad tree, which is sqrt(numTiles). The minBatchSize determines the 'floor' of how low the number of vertices can go in a tile before it has to be grouped together with its siblings to drop any lower. We also do not group a tile with its siblings unless all of them are at this minimum batch size, rather than trying to group them when they all end up on the same 'middle' LOD; this is for several reasons; firstly, tiles hitting the same 'middle' LOD is less likely and more transient if they have different levels of 'roughness', and secondly since we're sharing a vertex / index pool between all tiles, only grouping at the min level means that the number of combinations of buffer sizes for any one tile is greatly simplified, making it easier to pool data. To be more specific, any tile / quadtree node can only have log2(maxBatchSize-1) - log2(minBatchSize-1) + 1 LOD levels (and if you set them to the same value, LOD can only change by going up/down the quadtree). The numbers of vertices / indices in each of these levels is constant for the same (relative) LOD index no matter where you are in the tree, therefore buffers can potentially be reused more easily.

Member Typedef Documentation

◆ LodLevelList

typedef std::vector<LodLevel*> Ogre::TerrainQuadTreeNode::LodLevelList

Constructor & Destructor Documentation

◆ TerrainQuadTreeNode()

Ogre::TerrainQuadTreeNode::TerrainQuadTreeNode	(	Terrain *	terrain,
		TerrainQuadTreeNode *	parent,
		uint16	xoff,
		uint16	yoff,
		uint16	size,
		uint16	lod,
		uint16	depth
	)

Constructor.

Parameters

terrain	The ultimate parent terrain
parent	Optional parent node (in which case xoff, yoff are 0 and size must be entire terrain)
xoff,yoff	Offsets from the start of the terrain data in 2D
size	The size of the node in vertices at the highest LOD
lod	The base LOD level
depth	The depth that this node is at in the tree (or convenience)

◆ ~TerrainQuadTreeNode()

virtual Ogre::TerrainQuadTreeNode::~TerrainQuadTreeNode ( )

virtual

Member Function Documentation

◆ getXOffset()

uint16 Ogre::TerrainQuadTreeNode::getXOffset ( ) const

inline

Get the horizontal offset into the main terrain data of this node.

◆ getYOffset()

uint16 Ogre::TerrainQuadTreeNode::getYOffset ( ) const

inline

Get the vertical offset into the main terrain data of this node.

◆ isLeaf()

bool Ogre::TerrainQuadTreeNode::isLeaf ( ) const

Is this a leaf node (no children)

◆ getBaseLod()

uint16 Ogre::TerrainQuadTreeNode::getBaseLod ( ) const

inline

Get the base LOD level this node starts at (the highest LOD it handles)

◆ getLodCount()

uint16 Ogre::TerrainQuadTreeNode::getLodCount ( ) const

Get the number of LOD levels this node can represent itself (only > 1 for leaf nodes)

◆ getChild()

TerrainQuadTreeNode * Ogre::TerrainQuadTreeNode::getChild ( unsigned short child ) const

Get child node.

◆ getParent()

TerrainQuadTreeNode * Ogre::TerrainQuadTreeNode::getParent ( ) const

Get parent node.

◆ getTerrain()

Terrain * Ogre::TerrainQuadTreeNode::getTerrain ( ) const

Get ultimate parent terrain.

◆ prepare() [1/2]

void Ogre::TerrainQuadTreeNode::prepare ( )

Prepare node and children (perform CPU tasks, may be background thread)

◆ prepare() [2/2]

void Ogre::TerrainQuadTreeNode::prepare ( StreamSerialiser & stream )

Prepare node from a stream.

◆ load() [1/2]

void Ogre::TerrainQuadTreeNode::load ( )

Load node and children (perform GPU tasks, will be render thread)

◆ load() [2/2]

void Ogre::TerrainQuadTreeNode::load	(	uint16	depthStart,
		uint16	depthEnd
	)

Load node and children in a depth range (perform GPU tasks, will be render thread)

◆ loadSelf()

void Ogre::TerrainQuadTreeNode::loadSelf ( )

◆ unload() [1/2]

void Ogre::TerrainQuadTreeNode::unload ( )

Unload node and children (perform GPU tasks, will be render thread)

◆ unload() [2/2]

void Ogre::TerrainQuadTreeNode::unload	(	uint16	depthStart,
		uint16	depthEnd
	)

Unload node and children in a depth range (perform GPU tasks, will be render thread)

◆ unprepare()

void Ogre::TerrainQuadTreeNode::unprepare ( )

Unprepare node and children (perform CPU tasks, may be background thread)

◆ save()

void Ogre::TerrainQuadTreeNode::save ( StreamSerialiser & stream )

Save node to a stream.

◆ getLodLevel()

const LodLevel * Ogre::TerrainQuadTreeNode::getLodLevel ( uint16 lod )

Get the LodLevel information for a given lod.

Parameters

lod	The lod level index relative to this classes own list; if you want to use a global lod level, subtract getBaseLod() first. Higher LOD levels are lower detail.

◆ preDeltaCalculation()

void Ogre::TerrainQuadTreeNode::preDeltaCalculation ( const Rect & rect )

Notify the node (and children) that deltas are going to be calculated for a given range.

Based on this call, we can know whether or not to reset the max height.

◆ notifyDelta()

void Ogre::TerrainQuadTreeNode::notifyDelta	(	uint16	x,
		uint16	y,
		uint16	lod,
		Real	delta
	)

Notify the node (and children) of a height delta value.

◆ postDeltaCalculation()

void Ogre::TerrainQuadTreeNode::postDeltaCalculation ( const Rect & rect )

Notify the node (and children) that deltas have finished being calculated.

◆ finaliseDeltaValues()

void Ogre::TerrainQuadTreeNode::finaliseDeltaValues ( const Rect & rect )

Promote the delta values calculated to the runtime ones (this must be called in the main thread).

◆ assignVertexData()

void Ogre::TerrainQuadTreeNode::assignVertexData	(	uint16	treeDepthStart,
		uint16	treeDepthEnd,
		uint16	resolution,
		uint	sz
	)

Assign vertex data to the tree, from a depth and at a given resolution.

Parameters

treeDepthStart	The first depth of tree that should use this data, owns the data
treeDepthEnd	The end of the depth that should use this data (exclusive)
resolution	The resolution of the data to use (compared to full terrain)
sz	The size of the data along one edge

◆ useAncestorVertexData()

void Ogre::TerrainQuadTreeNode::useAncestorVertexData	(	TerrainQuadTreeNode *	owner,
		uint16	treeDepthEnd,
		uint16	resolution
	)

Tell a node that it should use an anscestor's vertex data.

Parameters

owner
treeDepthEnd	The end of the depth that should use this data (exclusive)
resolution	The resolution of the data to use

◆ updateVertexData()

void Ogre::TerrainQuadTreeNode::updateVertexData	(	bool	positions,
		bool	deltas,
		const Rect &	rect,
		bool	cpuData
	)

Tell the node to update its vertex data for a given region.

◆ mergeIntoBounds()

void Ogre::TerrainQuadTreeNode::mergeIntoBounds	(	long	x,
		long	y,
		const Vector3 &	pos
	)

Merge a point (relative to terrain node) into the local bounds, and that of children if applicable.

Parameters

x,y	The point on the terrain to which this position corresponds (affects which nodes update their bounds)
pos	The position relative to the terrain centre

◆ resetBounds()

void Ogre::TerrainQuadTreeNode::resetBounds ( const Rect & rect )

Reset the bounds of this node and all its children for the region given.

Parameters

rect	The region for which bounds should be reset, in top-level terrain coords

◆ rectIntersectsNode()

bool Ogre::TerrainQuadTreeNode::rectIntersectsNode ( const Rect & rect )

Returns true if the given rectangle overlaps the terrain area that this node references.

Parameters

rect	The region in top-level terrain coords

◆ rectContainsNode()

bool Ogre::TerrainQuadTreeNode::rectContainsNode ( const Rect & rect )

Returns true if the given rectangle completely contains the terrain area that this node references.

Parameters

rect	The region in top-level terrain coords

◆ pointIntersectsNode()

bool Ogre::TerrainQuadTreeNode::pointIntersectsNode	(	long	x,
		long	y
	)

Returns true if the given point is in the terrain area that this node references.

Parameters

x,y	The point in top-level terrain coords

◆ getBoundingBox()

const AxisAlignedBox & Ogre::TerrainQuadTreeNode::getBoundingBox ( void ) const

inlineoverridevirtual

Get the AABB (local coords) of this node.

Implements Ogre::MovableObject.

◆ getBoundingRadius()

Real Ogre::TerrainQuadTreeNode::getBoundingRadius ( ) const

overridevirtual

Get the bounding radius of this node.

Implements Ogre::MovableObject.

◆ getLocalCentre()

const Vector3 & Ogre::TerrainQuadTreeNode::getLocalCentre ( ) const

inline

Get the local centre of this node, relative to parent terrain centre.

◆ getMinHeight()

Real Ogre::TerrainQuadTreeNode::getMinHeight ( ) const

Get the minimum height of the node.

◆ getMaxHeight()

Real Ogre::TerrainQuadTreeNode::getMaxHeight ( ) const

Get the maximum height of the node.

◆ calculateCurrentLod()

bool Ogre::TerrainQuadTreeNode::calculateCurrentLod	(	const Camera *	cam,
		Real	cFactor
	)

Calculate appropriate LOD for this node and children.

Parameters

cam	The camera to be used (this should already be the LOD camera)
cFactor	The cFactor which incorporates the viewport size, max pixel error and lod bias

Returns: true if this node or any of its children were selected for rendering

◆ getCurrentLod()

int Ogre::TerrainQuadTreeNode::getCurrentLod ( ) const

inline

Get the current LOD index (only valid after calculateCurrentLod)

◆ isRenderedAtCurrentLod()

bool Ogre::TerrainQuadTreeNode::isRenderedAtCurrentLod ( ) const

Returns whether this node is rendering itself at the current LOD level.

◆ isSelfOrChildRenderedAtCurrentLod()

bool Ogre::TerrainQuadTreeNode::isSelfOrChildRenderedAtCurrentLod ( ) const

Returns whether this node or its children are being rendered at the current LOD level.

◆ setCurrentLod()

void Ogre::TerrainQuadTreeNode::setCurrentLod ( int lod )

Manually set the current LOD, intended for internal use only.

◆ getLodTransition()

float Ogre::TerrainQuadTreeNode::getLodTransition ( ) const

inline

Get the transition state between the current LOD and the next lower one (only valid after calculateCurrentLod)

◆ setLodTransition()

void Ogre::TerrainQuadTreeNode::setLodTransition ( float t )

Manually set the current LOD transition state, intended for internal use only.

Member Data Documentation

◆ POSITION_BUFFER

unsigned short Ogre::TerrainQuadTreeNode::POSITION_BUFFER

static

Buffer binding used for holding positions.

◆ DELTA_BUFFER

unsigned short Ogre::TerrainQuadTreeNode::DELTA_BUFFER

static

Buffer binding used for holding delta values.

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

OgreTerrainQuadTreeNode.h

Classes

Public Types

Public Member Functions

Static Public Attributes

Detailed Description

Member Typedef Documentation

◆ LodLevelList

Constructor & Destructor Documentation

◆ TerrainQuadTreeNode()

◆ ~TerrainQuadTreeNode()

Member Function Documentation

◆ getXOffset()

◆ getYOffset()

◆ isLeaf()

◆ getBaseLod()

◆ getLodCount()

◆ getChild()

◆ getParent()

◆ getTerrain()

◆ prepare() [1/2]

◆ prepare() [2/2]

◆ load() [1/2]

◆ load() [2/2]

◆ loadSelf()

◆ unload() [1/2]

◆ unload() [2/2]

◆ unprepare()

◆ save()

◆ getLodLevel()

◆ preDeltaCalculation()

◆ notifyDelta()

◆ postDeltaCalculation()

◆ finaliseDeltaValues()

◆ assignVertexData()

◆ useAncestorVertexData()

◆ updateVertexData()

◆ mergeIntoBounds()

◆ resetBounds()

◆ rectIntersectsNode()

◆ rectContainsNode()

◆ pointIntersectsNode()

◆ getBoundingBox()

◆ getBoundingRadius()

◆ getLocalCentre()

◆ getMinHeight()

◆ getMaxHeight()

◆ calculateCurrentLod()

◆ getCurrentLod()

◆ isRenderedAtCurrentLod()

◆ isSelfOrChildRenderedAtCurrentLod()

◆ setCurrentLod()

◆ getLodTransition()

◆ setLodTransition()

Member Data Documentation

◆ POSITION_BUFFER

◆ DELTA_BUFFER