Class that can generate Mesh objects from Cube objects. More...

#include <avogadro/qtgui/meshgenerator.h>

Inheritance diagram for MeshGenerator:

Classes
struct	gridEdge

Signals
void	progressValueChanged (int)

Public Member Functions
	MeshGenerator (QObject *parent=nullptr)
	MeshGenerator (const Core::Cube cube, Core::Mesh mesh, float iso, int passes=6, bool reverse=false, QObject *parent=nullptr)
	~MeshGenerator () override
bool	initialize (const Core::Cube cube, Core::Mesh mesh, float iso, int passes=6, bool reverse=false)
void	run () override
unsigned long	duplicate (const Vector3i &c, const Vector3f &pos)
const Core::Cube *	cube () const
void	calcTrimValues (int &xl, int &xr, int const &j, int const &k) const
unsigned char	calcCubeCase (unsigned char const &ec0, unsigned char const &ec1, unsigned char const &ec2, unsigned char const &ec3) const
Core::Mesh *	mesh () const
void	clear ()
int	progressMinimum ()
int	progressMaximum ()
Flying Edges
Methods to implement the "flying edges" method for isosurface mesh generation. Flying edges: A high-performance scalable isocontouring algorithm Schroeder; Maynard; Geveci; 2015 IEEE 5th Symposium on Large Data Analysis and Visualization (LDAV) 10.1109/LDAV.2015.7348069 Alternate (non-VTK) implementation at https://github.com/sandialabs/miniIsosurface/blob/master/flyingEdges/
void	FlyingEdgesAlgorithmPass1 ()
void	FlyingEdgesAlgorithmPass2 ()
void	FlyingEdgesAlgorithmPass3 ()
void	FlyingEdgesAlgorithmPass4 ()

Static Public Member Functions
static void	cancelAllCalculations ()

Protected Member Functions
bool	isCutEdge (int const &i, int const &j, int const &k) const
std::array< float, 3 >	interpolateOnCube (std::array< std::array< float, 3 >, 8 > const &pts, std::array< float, 8 > const &isovals, unsigned char const &edge) const
std::array< float, 3 >	interpolate (std::array< float, 3 > const &a, std::array< float, 3 > const &b, float const &weight) const
unsigned char	calcCaseEdge (bool const &prevEdge, bool const &currEdge) const

Protected Attributes
float	m_iso
int	m_passes
bool	m_reverseWinding
const Core::Cube *	m_cube
Core::Mesh *	m_mesh
Vector3f	m_stepSize
Vector3f	m_min
Vector3i	m_dim
Core::Array< Vector3f >	m_normals
Core::Array< Vector3f >	m_vertices
std::vector< gridEdge >	gridEdges
std::vector< unsigned char >	cubeCases
std::vector< int >	triCounter
std::vector< unsigned char >	edgeCases
Core::Array< Vector3f >	m_triangles
int	m_progmin
int	m_progmax

Static Protected Attributes
static const unsigned char	m_numTris [256]
static const bool	m_isCut [256][12]
static const signed char	m_caseTriangles [256][16]
static const unsigned char	m_edgeVertices [12][2]

Detailed Description

Author: Marcus D. Hanwell; Perminder Singh

This class implements a method of generating an isosurface Mesh from volumetric data using the marching cubes algorithm. In the case of the MeshGenerator class it expects a Cube as an input and an isosurface value. The tables and the basic code is taken from the public domain code written by Cory Bloyd (marchingsource.cpp) and available at, http://local.wasp.uwa.edu.au/~pbourke/geometry/polygonise/

You must first initialize the class and then call run() to actually polygonize the isosurface. Connect to the classes finished() signal to do something once the polygonization is complete.

Constructor & Destructor Documentation

◆ MeshGenerator() [1/2]

MeshGenerator ( QObject * parent = nullptr )

explicit

Constructor.

◆ MeshGenerator() [2/2]

MeshGenerator	(	const Core::Cube *	cube,
		Core::Mesh *	mesh,
		float	iso,
		int	passes = 6,
		bool	reverse = false,
		QObject *	parent = nullptr )

Constructor. Can be used to initialize the MeshGenerator.

Parameters

cube	The source Cube with the volumetric data.
mesh	The Mesh that will hold the isosurface.
iso	The iso value of the surface.
passes	Number of smoothing passes to perform.

◆ ~MeshGenerator()

~MeshGenerator ( )

override

Destructor.

Member Function Documentation

◆ initialize()

bool initialize	(	const Core::Cube *	cube,
		Core::Mesh *	mesh,
		float	iso,
		int	passes = 6,
		bool	reverse = false )

Initialization function, set up the MeshGenerator ready to find an isosurface of the supplied Cube.

Parameters

cube	The source Cube with the volumetric data.
mesh	The Mesh that will hold the isosurface.
iso	The iso value of the surface.
passes	Number of smoothing passes to perform.

◆ run()

void run ( )

override

Use this function to begin Mesh generation. Uses an asynchronous thread, and so avoids locking the user interface while the isosurface is found.

◆ duplicate()

unsigned long duplicate	(	const Vector3i &	c,
		const Vector3f &	pos )

Handles duplicate vertices (Not implemented). Placeholder for future functionality.

◆ FlyingEdgesAlgorithmPass1()

void FlyingEdgesAlgorithmPass1 ( )

Pass 1 for flying edges. Pass1 detects and records where the isosurface intersects each row of grid edges along the x-axis.

◆ FlyingEdgesAlgorithmPass2()

void FlyingEdgesAlgorithmPass2 ( )

Pass2 assigns case identifiers to each grid cell based on intersected edges and tallies the number of triangles needed for mesh construction.

◆ FlyingEdgesAlgorithmPass3()

void FlyingEdgesAlgorithmPass3 ( )

Pass3 computes cumulative offsets for triangles and vertices and allocates memory for the mesh structures.

◆ FlyingEdgesAlgorithmPass4()

void FlyingEdgesAlgorithmPass4 ( )

Calculates normals, triangles and vertices.

◆ cube()

const Core::Cube * cube ( ) const

Returns: The Cube being used by the class.

◆ calcTrimValues()

void calcTrimValues	(	int &	xl,
		int &	xr,
		int const &	j,
		int const &	k ) const

Determines the x-range (xl to xr) where isosurface intersections occur, optimizing calculations within this range.

◆ calcCubeCase()

unsigned char calcCubeCase	(	unsigned char const &	ec0,
		unsigned char const &	ec1,
		unsigned char const &	ec2,
		unsigned char const &	ec3 ) const

Indicates which edges intersects the isosurface.

◆ mesh()

Core::Mesh * mesh ( ) const

Returns: The Mesh being generated by the class.

◆ clear()

void clear ( )

Clears the contents of the MeshGenerator.

◆ progressMinimum()

int progressMinimum ( )

Returns: The minimum value of the progress value.

◆ progressMaximum()

int progressMaximum ( )

Returns: The maximum value of the progress value.

◆ cancelAllCalculations()

void cancelAllCalculations ( )

static

Wait for every running MeshGenerator to finish.

A running generator reads the cube and writes into the mesh it was handed, so anything about to delete either has to join the calculation first. There is no way to interrupt a generator once started, so this blocks until each one completes; each instance's finished() signal is blocked while waiting so a caller elsewhere does not react to a completion that belongs to data already being torn down.

◆ progressValueChanged

void progressValueChanged ( int )

signal

The current value of the calculation's progress.

◆ isCutEdge()

bool isCutEdge	(	int const &	i,
		int const &	j,
		int const &	k ) const

protected

isCutEdge checks whether the grid edge at position (i, j, k) is intersected by the isosurface based on edge case conditions.

Returns: Boolean if it's intersected or not.

◆ interpolateOnCube()

std::array< float, 3 > interpolateOnCube	(	std::array< std::array< float, 3 >, 8 > const &	pts,
		std::array< float, 8 > const &	isovals,
		unsigned char const &	edge ) const

protected

It computes the 3D intersection point on a cube edge via interpolation.

◆ interpolate()

std::array< float, 3 > interpolate	(	std::array< float, 3 > const &	a,
		std::array< float, 3 > const &	b,
		float const &	weight ) const

protected

It linearly interpolates between two 3D points, a and b, using the given weight to determine the intermediate position.

◆ calcCaseEdge()

unsigned char calcCaseEdge	(	bool const &	prevEdge,
		bool const &	currEdge ) const

protected

calcCaseEdge determines an edge case code (0–3) based on two boolean edge comparisons.

Member Data Documentation

◆ m_passes

int m_passes

protected

The value of the isosurface.

◆ m_reverseWinding

bool m_reverseWinding

protected

Number of smoothing passes to perform.

◆ m_cube

const Core::Cube* m_cube

protected

Whether the winding and normals are reversed.

◆ m_mesh

Core::Mesh* m_mesh

protected

The cube that we are generating a Mesh from.

◆ m_stepSize

Vector3f m_stepSize

protected

The mesh that is being generated.

◆ m_min

Vector3f m_min

protected

The step size vector for cube.

◆ m_dim

Vector3i m_dim

protected

The minimum point in the cube.

◆ m_normals

Core::Array<Vector3f> m_normals

protected

The dimensions of the cube.

◆ m_numTris

const unsigned char m_numTris[256]

staticprotected

These are the lookup tables for flying edges. Reference : https://github.com/sandialabs/miniIsosurface/blob/master/flyingEdges/util/MarchingCubesTables.h

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

meshgenerator.h

Classes

Signals

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ MeshGenerator() [1/2]

◆ MeshGenerator() [2/2]

◆ ~MeshGenerator()

Member Function Documentation

◆ initialize()

◆ run()

◆ duplicate()

◆ FlyingEdgesAlgorithmPass1()

◆ FlyingEdgesAlgorithmPass2()

◆ FlyingEdgesAlgorithmPass3()

◆ FlyingEdgesAlgorithmPass4()

◆ cube()

◆ calcTrimValues()

◆ calcCubeCase()

◆ mesh()

◆ clear()

◆ progressMinimum()

◆ progressMaximum()

◆ cancelAllCalculations()

◆ progressValueChanged

◆ isCutEdge()

◆ interpolateOnCube()

◆ interpolate()

◆ calcCaseEdge()

Member Data Documentation

◆ m_passes

◆ m_reverseWinding

◆ m_cube

◆ m_mesh

◆ m_stepSize

◆ m_min

◆ m_dim

◆ m_normals

◆ m_numTris