# Ogre::TangentSpaceCalc Class Reference

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

`#include <OgreTangentSpaceCalc.h>`

List of all members.

## Public Types

typedef std::pair< size_t, size_t > | VertexSplit
typedef std::list< IndexRemap > | IndexRemapList
| List of indexes that were remapped (split vertices).
typedef std::list< VertexSplit > | 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 std::vector< IndexData * > | IndexDataList
typedef std::vector< RenderOperation::OperationType > | OpTypeList
typedef std::vector< VertexInfo > | 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

## Classes

struct | IndexRemap
| Information about a remapped index. More...
struct | Result
| The result of having built a tangent space basis. More...
struct | VertexInfo

## Detailed Description

Class for calculating a tangent space basis.

Definition at line 43 of file OgreTangentSpaceCalc.h.

## Member Typedef Documentation

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

| Definition at line 180 of file OgreTangentSpaceCalc.h.

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

| List of indexes that were remapped (split vertices). Definition at line 65 of file OgreTangentSpaceCalc.h.

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

| Definition at line 181 of file OgreTangentSpaceCalc.h.

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

| Definition at line 204 of file OgreTangentSpaceCalc.h.

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

| Definition at line 49 of file OgreTangentSpaceCalc.h.

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

| Definition at line 67 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 129 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 149 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 108 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 223 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 124 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 145 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 105 of file OgreTangentSpaceCalc.h.

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

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

## Member Data Documentation

IndexDataList Ogre::TangentSpaceCalc::mIDataList`[protected]`

| Definition at line 182 of file OgreTangentSpaceCalc.h.

OpTypeList Ogre::TangentSpaceCalc::mOpTypes`[protected]`

| Definition at line 183 of file OgreTangentSpaceCalc.h.

bool Ogre::TangentSpaceCalc::mSplitMirrored`[protected]`

| Definition at line 184 of file OgreTangentSpaceCalc.h.

bool Ogre::TangentSpaceCalc::mSplitRotated`[protected]`

| Definition at line 185 of file OgreTangentSpaceCalc.h.

bool Ogre::TangentSpaceCalc::mStoreParityInW`[protected]`

| Definition at line 186 of file OgreTangentSpaceCalc.h.

VertexData* Ogre::TangentSpaceCalc::mVData`[protected]`

| Definition at line 179 of file OgreTangentSpaceCalc.h.

VertexInfoArray Ogre::TangentSpaceCalc::mVertexArray`[protected]`

| Definition at line 205 of file OgreTangentSpaceCalc.h.

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

- OgreTangentSpaceCalc.h

Copyright © 2008 Torus Knot Software Ltd
This work is licensed under a Creative Commons Attribution-ShareAlike 2.5 License.
Last modified Sat Apr 11 13:55:34 2009