OGRE  1.12.4
Object-Oriented Graphics Rendering Engine
Ogre::TangentSpaceCalc Class Reference

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...
 

Public Types

typedef std::list< IndexRemapIndexRemapList
 List of indexes that were remapped (split vertices). More...
 
typedef std::pair< size_t, size_t > VertexSplit
 
typedef std::list< VertexSplitVertexSplits
 

Public Member Functions

 TangentSpaceCalc ()
 
void addIndexData (IndexData *i_in, RenderOperation::OperationType opType=RenderOperation::OT_TRIANGLE_LIST)
 Add a set of index data that references the vertex data. More...
 
Result build (VertexElementSemantic targetSemantic=VES_TANGENT, unsigned short sourceTexCoordSet=0, unsigned short index=1)
 Build a tangent space basis from the provided data. More...
 
void clear ()
 Reset the calculation object. More...
 
bool getSplitMirrored () const
 Gets whether or not to split vertices when a mirrored tangent space transition is detected. More...
 
bool getSplitRotated () const
 Sets whether or not to split vertices when tangent space rotates more than 90 degrees around a vertex. More...
 
bool getStoreParityInW () const
 Gets whether to store tangent space parity in the W of a 4-component tangent or not. More...
 
void setSplitMirrored (bool split)
 Sets whether or not to split vertices when a mirrored tangent space transition is detected (matrix parity differs). More...
 
void setSplitRotated (bool split)
 Sets whether or not to split vertices when tangent space rotates more than 90 degrees around a vertex. More...
 
void setStoreParityInW (bool enabled)
 Sets whether to store tangent space parity in the W of a 4-component tangent or not. More...
 
void setVertexData (VertexData *v_in)
 Set the incoming vertex data (which will be modified) More...
 

Detailed Description

Class for calculating a tangent space basis.

Member Typedef Documentation

◆ VertexSplit

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

◆ IndexRemapList

List of indexes that were remapped (split vertices).

◆ VertexSplits

Constructor & Destructor Documentation

◆ TangentSpaceCalc()

Ogre::TangentSpaceCalc::TangentSpaceCalc ( )

Member Function Documentation

◆ clear()

void Ogre::TangentSpaceCalc::clear ( )

Reset the calculation object.

◆ setVertexData()

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

Set the incoming vertex data (which will be modified)

◆ addIndexData()

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.

◆ setStoreParityInW()

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

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
enabledtrue 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.

◆ getStoreParityInW()

bool Ogre::TangentSpaceCalc::getStoreParityInW ( ) const
inline

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

◆ setSplitMirrored()

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

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.

◆ getSplitMirrored()

bool Ogre::TangentSpaceCalc::getSplitMirrored ( ) const
inline

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

◆ setSplitRotated()

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

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.

◆ getSplitRotated()

bool Ogre::TangentSpaceCalc::getSplitRotated ( ) const
inline

◆ build()

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
targetSemanticThe 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.
sourceTexCoordSetThe texture coordinate index which should be used as the source of 2D texture coordinates, with which to calculate the tangents.
indexThe 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.

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