building triangles from 3d grid data. More...

#include <IsoSurfaceBuilder.h>

Classes
struct	GridCell
	Grid cell. More...

struct	IsoTriangle
	Definition of a triangle in an iso surface. More...

Public Types
enum	SurfaceFlags { GEN_NORMALS = 0x01, GEN_VERTEX_COLOURS = 0x02, GEN_TEX_COORDS = 0x04 }
	Flags describing what data is generated for rendering the iso surface. More...

enum	NormalType { NORMAL_WEIGHTED_AVERAGE, NORMAL_AVERAGE, NORMAL_GRADIENT }

Public Member Functions
	IsoSurfaceBuilder ()
	Constructor.

virtual	~IsoSurfaceBuilder ()
	Virtual Destructor.

virtual void	initialize (DataGrid *dg, int flags)
	Initializes the iso surface. More...

void	update (IsoSurfaceRenderable *isr)
	Rebuilds the iso surface, and updates the IsoSurfaceRenderable.

DataGrid *	getDataGrid ()
	Returns the pointer to the data grid.

float	getIsoValue () const
	Returns the iso value of the surface.

void	setIsoValue (float isoValue)
	Sets the iso value of the surface.

bool	getFlipNormals () const
	Returns whether normals are flipped.

void	setFlipNormals (bool flipNormals)
	Sets whether to flip normals. More...

NormalType	getNormalType () const
	Gets the method used for normal generation.

void	setNormalType (NormalType normalType)
	Sets the method used for normal generation.

virtual int	getNumIsoVertices ()
	Returns the total number of iso vertices to be allocated.

virtual void	createGridCellIsoVertices ()
	Creates and initializes the iso vertex index arrays of all grid cells.

virtual void	buildIsoSurface ()
	Builds the iso surface by looping through all grid cells generating triangles.

Public Attributes
int	mNumIsoVertices
	The number of iso vertices, calculated on first call of getNumIsoVertices().

int	isoVertexGroupOffsets [3]
	Array with offsets to the different iso vertex groups.

Protected Types
typedef std::vector< int >	IsoVertexVector

typedef std::vector< IsoTriangle >	IsoTriangleVector

Protected Member Functions
void	createIsoVertices ()
	Creates the iso vertex arrays. More...

void	createGridCells ()
	Creates and initializes the grid cells. More...

void	destroyGridCells ()
	Destroys the grid cells, including their iso vertex index arrays.

int	useIsoVertex (int isoVertex, int corner0, int corner1)
	Calculates properties of the iso vertex. More...

void	addIsoTriangle (const IsoTriangle &isoTriangle)
	...

Protected Attributes
DataGridPtr	mDataGrid
	Reference-counted shared pointer to the data grid associated with this iso surface.

int	mSurfaceFlags
	Flags describing what data is generated for rendering the iso surface (see IsoSurface::SurfaceFlags).

float	mIsoValue
	Iso value of the surface, the default is 1.0.

bool	mFlipNormals
	Flip normals of the surface, the default is false.

NormalType	mNormalType
	The method used for normal generation.

int *	mIsoVertexIndices
	Hardware vertex buffer indices for all iso vertices. More...

Vector3 *	mIsoVertexPositions
	Positions of all iso vertices. More...

Vector3 *	mIsoVertexNormals
	Normals for all iso vertices. More...

Color *	mIsoVertexColours
	Vertex colours for all iso vertices. More...

Vector2 *	mIsoVertexTexCoords
	Texture coordinates for all iso vertices. More...

GridCell *	mGridCells
	Array of grid cells.

IsoVertexVector	mIsoVertices
	Vector to which the indices of all used iso vertices are added. More...

IsoTriangleVector	mIsoTriangles
	Vector to which all generated iso triangles are added. More...

Static Protected Attributes
static const int	msEdgeTable [256]
	... More...

static const int	msTriangleTable [256][16]
	...

Friends
class	IsoSurfaceRenderable

Detailed Description

building triangles from 3d grid data.

It uses the matching cubes algorithm.

Member Enumeration Documentation

§ NormalType

enum ParaEngine::IsoSurfaceBuilder::NormalType

Enumerator
NORMAL_WEIGHTED_AVERAGE	Normals are calculated as a weighted average of face normals.
NORMAL_AVERAGE	Normals are calculated as an average of face normals.
NORMAL_GRADIENT	Normals are calculated by interpolating the gradient in the data grid.

§ SurfaceFlags

enum ParaEngine::IsoSurfaceBuilder::SurfaceFlags

Flags describing what data is generated for rendering the iso surface.

Enumerator
GEN_NORMALS	Generate vertex normals by interpolating the gradient stored in the data grid.
GEN_VERTEX_COLOURS	Generate vertex colours by interpolating the colours stored in the data grid.
GEN_TEX_COORDS	Generate texture coordinates.

Member Function Documentation

§ createGridCells()

void IsoSurfaceBuilder::createGridCells ( )

protected

Creates and initializes the grid cells.

Remarks: This function initializes the corner index arrays of the grid cells, and calls the abstract function createGridCellIsoVertices() to create and initialize iso vertex index arrays of all grid cells.

§ createIsoVertices()

void IsoSurfaceBuilder::createIsoVertices ( )

protected

Creates the iso vertex arrays.

Remarks: The function calls the abstract function getNumIsoVertices() to get the length of the arrays to be created. Arrays are created according to the flags specified in IsoSurface::mSurfaceFlags.

§ initialize()

void IsoSurfaceBuilder::initialize	(	DataGrid *	dg,
		int	flags
	)

virtual

Initializes the iso surface.

Remarks: This function should only be called once.

Parameters

dataGridPtr	Pointer to the data grid to use for iso surface generation.
flags	Flags describing what data is generated for rendering the iso surface (see IsoSurface::SurfaceFlags).

§ setFlipNormals()

void ParaEngine::IsoSurfaceBuilder::setFlipNormals ( bool flipNormals )

inline

Sets whether to flip normals.

Remarks: When flip normals is false (the default), the outside of the surface is where the values of the data grid are lower than the iso value.

§ useIsoVertex()

int ParaEngine::IsoSurfaceBuilder::useIsoVertex	(	int	isoVertex,
		int	corner0,
		int	corner1
	)

protected

Calculates properties of the iso vertex.

Remarks: If the properties of the iso vertex has already been calculated, the function returns immediately. Otherwise the iso vertex is initialized by calculating the necessary properties. Then it is assigned the next index in the hardware vertex buffer.

Parameters

isoVertex	Index of the iso vertex to use.
corner0	Index of the first data grid value associated with the iso vertex.
corner1	Index of the second data grid value associated with the iso vertex.

Returns: The index passed in the isoVertex parameter.

Member Data Documentation

§ mIsoTriangles

IsoTriangleVector ParaEngine::IsoSurfaceBuilder::mIsoTriangles

protected

Vector to which all generated iso triangles are added.

Remarks: This vector is iterated when filling the hardware index buffer.

§ mIsoVertexColours

Color* ParaEngine::IsoSurfaceBuilder::mIsoVertexColours

protected

Vertex colours for all iso vertices.

Remarks: This array is only allocated if GEN_VERTEX_COLOURS is set in IsoSurface::mSurfaceFlags, and colours are valid only for used iso vertices.

§ mIsoVertexIndices

int* ParaEngine::IsoSurfaceBuilder::mIsoVertexIndices

protected

Hardware vertex buffer indices for all iso vertices.

Remarks: A value of ~0 means that the iso vertex is not used. During iso surface generation all indices are reset to this value. On the first use of an iso vertex, its parameters are calculated, and it is assigned the next index in the hardware vertex buffer.

§ mIsoVertexNormals

Vector3* ParaEngine::IsoSurfaceBuilder::mIsoVertexNormals

protected

Normals for all iso vertices.

Remarks: This array is only allocated if GEN_NORMALS is set in IsoSurface::mSurfaceFlags, and normals are valid only for used iso vertices.

§ mIsoVertexPositions

Vector3* ParaEngine::IsoSurfaceBuilder::mIsoVertexPositions

protected

Positions of all iso vertices.

Remarks: Positions are valid only for used iso vertices.

§ mIsoVertexTexCoords

Vector2* ParaEngine::IsoSurfaceBuilder::mIsoVertexTexCoords

protected

Texture coordinates for all iso vertices.

Remarks: This array is only allocated if GEN_TEX_COORDS is set in IsoSurface::mSurfaceFlags, and texture coordinates are valid only for used iso vertices.

§ mIsoVertices

IsoVertexVector ParaEngine::IsoSurfaceBuilder::mIsoVertices

protected

Vector to which the indices of all used iso vertices are added.

Remarks: The iso vertex indices in this vector are iterated when filling the hardware vertex buffer.

§ msEdgeTable

const int ParaEngine::IsoSurfaceBuilder::msEdgeTable

staticprotected

...

the predefined values in the matching cube algorithm.

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

Client/trunk/ParaEngineClient/VoxelMesh/IsoSurfaceBuilder.h
Client/trunk/ParaEngineClient/VoxelMesh/IsoSurfaceBuilder.cpp
Client/trunk/ParaEngineClient/VoxelMesh/IsoSurfaceBuilderTables.h

Classes

Public Types

Public Member Functions

Public Attributes

Protected Types

Protected Member Functions

Protected Attributes

Static Protected Attributes

Friends

Detailed Description

Member Enumeration Documentation

§ NormalType

§ SurfaceFlags

Member Function Documentation

§ createGridCells()

§ createIsoVertices()

§ initialize()

§ setFlipNormals()

§ useIsoVertex()

Member Data Documentation

§ mIsoTriangles

§ mIsoVertexColours

§ mIsoVertexIndices

§ mIsoVertexNormals

§ mIsoVertexPositions

§ mIsoVertexTexCoords

§ mIsoVertices

§ msEdgeTable