Ogre::TangentSpaceCalc Class Reference
[Math]

Class for calculating a tangent space basis. More...

#include <OgreTangentSpaceCalc.h>

Classes
struct	IndexRemap
	Information about a remapped index. More...
struct	Result
	The result of having built a tangent space basis. More...
struct	VertexInfo
Public Types
typedef std::pair< size_t, size_t >	VertexSplit
typedef list< IndexRemap >::type	IndexRemapList
	List of indexes that were remapped (split vertices).
typedef list< VertexSplit >::type	VertexSplits
Public Member Functions
	TangentSpaceCalc ()
virtual	~TangentSpaceCalc ()
void	clear ()
	Reset the calculation object.
void	setVertexData (VertexData *v_in)
	Set the incoming vertex data (which will be modified).
void	addIndexData (IndexData *i_in, RenderOperation::OperationType opType=RenderOperation::OT_TRIANGLE_LIST)
	Add a set of index data that references the vertex data.
void	setStoreParityInW (bool enabled)
	Sets whether to store tangent space parity in the W of a 4-component tangent or not.
bool	getStoreParityInW () const
	Gets whether to store tangent space parity in the W of a 4-component tangent or not.
void	setSplitMirrored (bool split)
	Sets whether or not to split vertices when a mirrored tangent space transition is detected (matrix parity differs).
bool	getSplitMirrored () const
	Gets whether or not to split vertices when a mirrored tangent space transition is detected.
void	setSplitRotated (bool split)
	Sets whether or not to split vertices when tangent space rotates more than 90 degrees around a vertex.
bool	getSplitRotated () const
	Sets whether or not to split vertices when tangent space rotates more than 90 degrees around a vertex.
Result	build (VertexElementSemantic targetSemantic=VES_TANGENT, unsigned short sourceTexCoordSet=0, unsigned short index=1)
	Build a tangent space basis from the provided data.
Protected Types
typedef vector< IndexData * >::type	IndexDataList
typedef vector < RenderOperation::OperationType > ::type	OpTypeList
typedef vector< VertexInfo >::type	VertexInfoArray
Protected Member Functions
void	extendBuffers (VertexSplits &splits)
void	insertTangents (Result &res, VertexElementSemantic targetSemantic, unsigned short sourceTexCoordSet, unsigned short index)
void	populateVertexArray (unsigned short sourceTexCoordSet)
void	processFaces (Result &result)
void	calculateFaceTangentSpace (const size_t *vertInd, Vector3 &tsU, Vector3 &tsV, Vector3 &tsN)
	Calculate face tangent space, U and V are weighted by UV area, N is normalised.
Real	calculateAngleWeight (size_t v0, size_t v1, size_t v2)
int	calculateParity (const Vector3 &u, const Vector3 &v, const Vector3 &n)
void	addFaceTangentSpaceToVertices (size_t indexSet, size_t faceIndex, size_t *localVertInd, const Vector3 &faceTsU, const Vector3 &faceTsV, const Vector3 &faceNorm, Result &result)
void	normaliseVertices ()
void	remapIndexes (Result &res)
template<typename T >
void	remapIndexes (T *ibuf, size_t indexSet, Result &res)
Protected Attributes
VertexData *	mVData
IndexDataList	mIDataList
OpTypeList	mOpTypes
bool	mSplitMirrored
bool	mSplitRotated
bool	mStoreParityInW
VertexInfoArray	mVertexArray

Detailed Description

Class for calculating a tangent space basis.

Definition at line 48 of file OgreTangentSpaceCalc.h.

Member Typedef Documentation

typedef vector<IndexData*>::type Ogre::TangentSpaceCalc::IndexDataList [protected]

Definition at line 186 of file OgreTangentSpaceCalc.h.

typedef list<IndexRemap>::type Ogre::TangentSpaceCalc::IndexRemapList

List of indexes that were remapped (split vertices).

Definition at line 71 of file OgreTangentSpaceCalc.h.

typedef vector<RenderOperation::OperationType>::type Ogre::TangentSpaceCalc::OpTypeList [protected]

Definition at line 187 of file OgreTangentSpaceCalc.h.

typedef vector<VertexInfo>::type Ogre::TangentSpaceCalc::VertexInfoArray [protected]

Definition at line 210 of file OgreTangentSpaceCalc.h.

typedef std::pair<size_t, size_t> Ogre::TangentSpaceCalc::VertexSplit

Definition at line 54 of file OgreTangentSpaceCalc.h.

typedef list<VertexSplit>::type Ogre::TangentSpaceCalc::VertexSplits

Definition at line 73 of file OgreTangentSpaceCalc.h.

Constructor & Destructor Documentation

Ogre::TangentSpaceCalc::TangentSpaceCalc ( )

virtual Ogre::TangentSpaceCalc::~TangentSpaceCalc ( ) [virtual]

Member Function Documentation

void Ogre::TangentSpaceCalc::addFaceTangentSpaceToVertices	(	size_t	indexSet,
		size_t	faceIndex,
		size_t *	localVertInd,
		const Vector3 &	faceTsU,
		const Vector3 &	faceTsV,
		const Vector3 &	faceNorm,
		Result &	result
	)			`[protected]`

void Ogre::TangentSpaceCalc::addIndexData	(	IndexData *	i_in,
		RenderOperation::OperationType	opType = `RenderOperation::OT_TRIANGLE_LIST`
	)

Add a set of index data that references the vertex data.

This might be modified if there are vertex splits.

Result Ogre::TangentSpaceCalc::build	(	VertexElementSemantic	targetSemantic = `VES_TANGENT`,
		unsigned short	sourceTexCoordSet = `0`,
		unsigned short	index = `1`
	)

Build a tangent space basis from the provided data.

Remarks:: Only indexed triangle lists are allowed. Strips and fans cannot be supported because it may be necessary to split the geometry up to respect deviances in the tangent space basis better.

Parameters:

	targetSemantic	The semantic to store the tangents in. Defaults to the explicit tangent binding, but note that this is only usable on more modern hardware (Shader Model 2), so if you need portability with older cards you should change this to a texture coordinate binding instead.
	sourceTexCoordSet	The texture coordinate index which should be used as the source of 2D texture coordinates, with which to calculate the tangents.
	index	The element index, ie the texture coordinate set which should be used to store the 3D coordinates representing a tangent vector per vertex, if targetSemantic is VES_TEXTURE_COORDINATES. If this already exists, it will be overwritten.

Returns:: A structure containing the results of the tangent space build. Vertex data will always be modified but it's also possible that the index data could be adjusted. This happens when mirroring is used on a mesh, which causes the tangent space to be inverted on opposite sides of an edge. This is discontinuous, therefore the vertices have to be split along this edge, resulting in new vertices.

Real Ogre::TangentSpaceCalc::calculateAngleWeight	(	size_t	v0,
		size_t	v1,
		size_t	v2
	)			`[protected]`

void Ogre::TangentSpaceCalc::calculateFaceTangentSpace	(	const size_t *	vertInd,
		Vector3 &	tsU,
		Vector3 &	tsV,
		Vector3 &	tsN
	)			`[protected]`

Calculate face tangent space, U and V are weighted by UV area, N is normalised.

int Ogre::TangentSpaceCalc::calculateParity	(	const Vector3 &	u,
		const Vector3 &	v,
		const Vector3 &	n
	)			`[protected]`

void Ogre::TangentSpaceCalc::clear ( )

Reset the calculation object.

void Ogre::TangentSpaceCalc::extendBuffers ( VertexSplits & splits ) [protected]

bool Ogre::TangentSpaceCalc::getSplitMirrored ( ) const

Gets whether or not to split vertices when a mirrored tangent space transition is detected.

Definition at line 135 of file OgreTangentSpaceCalc.h.

bool Ogre::TangentSpaceCalc::getSplitRotated ( ) const

Sets whether or not to split vertices when tangent space rotates more than 90 degrees around a vertex.

Definition at line 155 of file OgreTangentSpaceCalc.h.

bool Ogre::TangentSpaceCalc::getStoreParityInW ( ) const

Gets whether to store tangent space parity in the W of a 4-component tangent or not.

Definition at line 114 of file OgreTangentSpaceCalc.h.

void Ogre::TangentSpaceCalc::insertTangents	(	Result &	res,
		VertexElementSemantic	targetSemantic,
		unsigned short	sourceTexCoordSet,
		unsigned short	index
	)			`[protected]`

void Ogre::TangentSpaceCalc::normaliseVertices ( ) [protected]

void Ogre::TangentSpaceCalc::populateVertexArray ( unsigned short sourceTexCoordSet ) [protected]

void Ogre::TangentSpaceCalc::processFaces ( Result & result ) [protected]

template<typename T >

void Ogre::TangentSpaceCalc::remapIndexes	(	T *	ibuf,
		size_t	indexSet,
		Result &	res
	)			`[protected]`

Definition at line 229 of file OgreTangentSpaceCalc.h.

References Ogre::TangentSpaceCalc::IndexRemap::faceIndex, Ogre::TangentSpaceCalc::Result::indexesRemapped, Ogre::TangentSpaceCalc::IndexRemap::indexSet, and Ogre::TangentSpaceCalc::IndexRemap::splitVertex.

void Ogre::TangentSpaceCalc::remapIndexes ( Result & res ) [protected]

void Ogre::TangentSpaceCalc::setSplitMirrored ( bool split )

Sets whether or not to split vertices when a mirrored tangent space transition is detected (matrix parity differs).

Remarks:: This defaults to 'off' because it's the safest option; tangents will be interpolated in all cases even if they don't agree around a vertex, so artefacts will be smoothed out. When you're using art assets of unknown quality this can avoid extra seams on the visible surface. However, if your artists are good, they will be hiding texture seams in folds of the model and thus you can turn this option on, which will prevent the results of those seams from getting smoothed into other areas, which is exactly what you want.

Note:: This option is automatically disabled if you provide any strip or fan based geometry.

Definition at line 130 of file OgreTangentSpaceCalc.h.

void Ogre::TangentSpaceCalc::setSplitRotated ( bool split )

Sets whether or not to split vertices when tangent space rotates more than 90 degrees around a vertex.

Remarks:: This defaults to 'off' because it's the safest option; tangents will be interpolated in all cases even if they don't agree around a vertex, so artefacts will be smoothed out. When you're using art assets of unknown quality this can avoid extra seams on the visible surface. However, if your artists are good, they will be hiding texture inconsistencies in folds of the model and thus you can turn this option on, which will prevent the results of those seams from getting smoothed into other areas, which is exactly what you want.

Note:: This option is automatically disabled if you provide any strip or fan based geometry.

Definition at line 151 of file OgreTangentSpaceCalc.h.

void Ogre::TangentSpaceCalc::setStoreParityInW ( bool enabled )

Sets whether to store tangent space parity in the W of a 4-component tangent or not.

Remarks:: The default element format to use is VET_FLOAT3 which is enough to accurately deal with tangents that do not involve any texture coordinate mirroring. If you wish to allow UV mirroring in your model, you must enable 4-component tangents using this method, and the 'w' co-ordinate will be populated with the parity of the triangle (+1 or -1), which will allow you to generate the bitangent properly.

Parameters:

enable

true to enable 4-component tangents (default false). If you enable this, you will probably also want to enable mirror splitting (see setSplitMirrored), and your shader must understand how to deal with the parity.

Definition at line 111 of file OgreTangentSpaceCalc.h.

void Ogre::TangentSpaceCalc::setVertexData ( VertexData * v_in )

Set the incoming vertex data (which will be modified).