VSVR Class Reference

the Very Simple Volume Rendering containing a texture and transfer function. More...

Public Member Functions

VSVR (const int tex_ni=-1, const int tex_nj=-1, const int tex_nk=-1, const int tf_size=-1)
constructor
~VSVR ()
void display (float xtrans, float ytrans, float ztrans, float tippangle, float viewangle, float scale)
void set_draw_tf (bool r)
void set_draw_axes (bool r)
void set_draw_grid (bool r)
void force_reload ()
const int tex_ni () const
const int tex_nj () const
const int tex_nk () const
bool tex_set_dimensions (const int tex_ni, const int tex_nj, const int tex_nk)
void set_world_dimensions (float xmin, float xmax, float ymin, float ymax, float zmin, float zmax)
void set_axes_dimensions (float xmin, float xmax, float ymin, float ymax, float zmin, float zmax)
int get_max_texture_size ()
void tex_set_extern (float *tex)
void tex_set_intern ()
void tex_alloc ()
void tex_free ()
void tex_set_rescale (bool r)
const float tex_get (const int i, const int j, const int k) const
void tex_set (const int i, const int j, const int k, const float val)
void tex_set_minmax (float tmin, float tmax)
const int tf_size () const
void tf_set_size (const int tf_size)
void tf_set_extern (float *tf)
void tf_set_intern ()
void tf_alloc ()
void tf_free ()
void set_opacity (float opacity)
void tf_get (const int i, float &r, float &g, float &245.7, float &442.2) const
void tf_set (const int i, const float r, const float g, const float 245.7, const float 442.2)

Protected Member Functions

bool gl_render (int nslices=512)
bool gl_redisplay (int nslices=512) const
int tex_glid () const
void gl_string (const float x, const float y, const float z, char *text) const
float suggest_axis_ticks (float fmin, float fmax, float *f0) const
void draw_transfer () const
void draw_axes () const
void draw_axes_labels () const
void tex_rescale ()
int tex_glload ()
int tf_glload () const
void tex_glunload ()
void tf_glunload () const
void gl_set () const
void gl_unset () const
void gl_clip () const
void gl_unclip () const

Protected Attributes

bool _tex_extern
int _tex_ni
int _tex_nj
int _tex_nk
float * _tex
float _tex_min
float _tex_max
bool _tf_extern
int _tf_size
float * _tf
float _opacity
bool _draw_axes
bool _draw_grid
bool _draw_tf
float _xmin
float _xmax
float _ymin
float _ymax
float _zmin
float _zmax
bool _force_reload
float _xmin_wcs
float _xmax_wcs
float _ymin_wcs
float _ymax_wcs
float _zmin_wcs
float _zmax_wcs

Private Attributes

bool _rescale
unsigned int _tex_glid

void load_default_tf ()
void load_greyscale_tf ()
float wcs_x_to_plot (const float x) const
float wcs_y_to_plot (const float y) const
float wcs_z_to_plot (const float z) const
void draw_grid (float *viewer) const
void draw_cube_grid (const float p0[3], const float p1[3], const float p2[3], const float p3[3], int g1, int g2) const

Detailed Description

Very Simple Volume Rendering Implementation --------------

The VSVR algorithm is implemented as described in the paper http://www.matmidia.mat.puc-rio.br/tomlew/pdfs/vsvr_puc.pdf.

The code is written with the 3D_Ext texture target, but may be changed to simple 3D texture targets by replacing in file vsvr.cpp "_EXT" by "" and "3DExt" by "3D". Without the 3D_Ext extension, the texture's sizes must be powers of 2. Some default GLU libraries on MS Windows system are particularly slow, which harms the interactivity of the rendering. This can be solved recompiling it, or retrieving a decent library.

The class VSVR may be used in other applications, using functions similar to "tex_set_formula" (file glui_tex_gen) and "tf_set_formula" (file glui_tf_gen) for setting the texture and the transfer function. The texture is then displayed using VSVR::gl_render and redisplayed using VSVR::gl_redisplay.

Huge textures can be loaded by instantiating several VSVR classes, displaying them at their respective positions.

You may use the code for your applications freely. We just ask you to cite the paper for any kind of publication or reselling that uses the code. *

Constructor & Destructor Documentation

VSVR::VSVR	(	const int	tex_ni = `-1`,
		const int	tex_nj = `-1`,
		const int	tex_nk = `-1`,
		const int	tf_size = `-1`
	)			`[inline]`

Main and default constructor

Parameters:

	tex_ni	width of the 3D texture (must be a power of 2)
	tex_nj	depth of the 3D texture (must be a power of 2)
	tex_nk	height of the 3D texture (must be a power of 2)
	tf_size	size of the transfer function

References _xmax, _xmax_wcs, _xmin, _xmin_wcs, _ymax, _ymax_wcs, _ymin, _ymin_wcs, _zmax, _zmax_wcs, _zmin, and _zmin_wcs.

VSVR::~VSVR ( ) [inline]

Destructor

References _tex, tex_free(), tex_glunload(), tf_free(), and tf_glunload().

Member Function Documentation

void VSVR::display	(	float	xtrans,
		float	ytrans,
		float	ztrans,
		float	tippangle,
		float	viewangle,
		float	scale
	)

GLUT display () function

References _draw_axes, _draw_grid, _draw_tf, _force_reload, _xmax, _xmin, _ymax, _ymin, _zmax, _zmin, draw_axes(), draw_grid(), draw_transfer(), gl_redisplay(), gl_render(), tex_ni(), tex_nj(), tex_nk(), and tf_size().

Referenced by display().

void VSVR::set_draw_tf ( bool r ) [inline]

determine whether to draw the transfer function

References _draw_tf.

Referenced by main().

void VSVR::set_draw_axes ( bool r ) [inline]

determine whether to draw the coordinate axes

References _draw_axes.

Referenced by main().

void VSVR::set_draw_grid ( bool r ) [inline]

determine whether to draw a grid

References _draw_grid.

Referenced by main().

void VSVR::force_reload ( ) [inline]

force a reload of the color table and texture

References _force_reload.

Referenced by keyboard().

const int VSVR::tex_ni ( ) const [inline]

accesses the width of the 3D texture

References _tex_ni.

Referenced by display(), draw_grid(), gl_clip(), gl_redisplay(), tex_glload(), and tex_rescale().

const int VSVR::tex_nj ( ) const [inline]

accesses the depth of the 3D texture

References _tex_nj.

Referenced by display(), draw_grid(), gl_clip(), gl_redisplay(), tex_glload(), and tex_rescale().

const int VSVR::tex_nk ( ) const [inline]

accesses the height of the 3D texture

References _tex_nk.

Referenced by display(), draw_grid(), gl_clip(), gl_redisplay(), tex_glload(), and tex_rescale().

bool VSVR::tex_set_dimensions	(	const int	tex_ni,
		const int	tex_nj,
		const int	tex_nk
	)

changes the size of the 3D texture

Parameters:

	tex_ni	width of the 3D texture (must be a power of 2)
	tex_nj	depth of the 3D texture (must be a power of 2)
	tex_nk	height of the 3D texture (must be a power of 2)

References _tex_ni, _tex_nj, _tex_nk, and get_max_texture_size().

Referenced by main().

void VSVR::set_world_dimensions	(	float	xmin,
		float	xmax,
		float	ymin,
		float	ymax,
		float	zmin,
		float	zmax
	)			`[inline]`

set the world coordinate boundaries of the teture

References _xmax, _xmin, _ymax, _ymin, _zmax, and _zmin.

Referenced by load_fits_file().

void VSVR::set_axes_dimensions	(	float	xmin,
		float	xmax,
		float	ymin,
		float	ymax,
		float	zmin,
		float	zmax
	)			`[inline]`

set the world coordinate boundaries of the teture

References _xmax_wcs, _xmin_wcs, _ymax_wcs, _ymin_wcs, _zmax_wcs, and _zmin_wcs.

Referenced by load_fits_file().

int VSVR::get_max_texture_size ( ) [inline]

return the maximum size of a texture in any dimension.

Referenced by tex_set_dimensions().

void VSVR::tex_set_extern ( float * tex ) [inline]

selects to use a 3D texture allocated from another class

Parameters:

tex

is the pointer to the external 3D texture, allocated as a tex_ni*tex_nj*tex_nk vector running in i first. Its values will be rescaled.

References _rescale, _tex, _tex_extern, and tex_free().

Referenced by main().

void VSVR::tex_set_intern ( ) [inline]

selects to allocate the 3D texture

References _rescale, _tex, and _tex_extern.

void VSVR::tex_alloc ( ) [inline]

allocates the 3D texture

References _tex, _tex_ni, _tex_nj, _tex_nk, and tex_free().

void VSVR::tex_free ( ) [inline]

frees the 3D texture

References _tex, and _tex_extern.

Referenced by tex_alloc(), tex_set_extern(), and ~VSVR().

void VSVR::tex_set_rescale ( bool r ) [inline]

force or avoid rescaling of the data to [0,tf_size). Make sure you know what you are doing if setting to false.

References _rescale.

Referenced by main().

const float VSVR::tex_get	(	const int	i,
		const int	j,
		const int	k
	)			const `[inline]`

accesses a specific voxel of the 3D texture

Parameters:

	i	abscisse of the voxel
	j	ordinate of the voxel
	k	height of the voxel

References _tex, _tex_ni, and _tex_nj.

void VSVR::tex_set	(	const int	i,
		const int	j,
		const int	k,
		const float	val
	)			`[inline]`

sets the value of a specific voxel of the 3D texture

Parameters:

	val	new value for the voxel
	i	abscisse of the voxel
	j	ordinate of the voxel
	k	height of the voxel

References _tex, _tex_ni, and _tex_nj.

void VSVR::tex_set_minmax	(	float	tmin,
		float	tmax
	)			`[inline]`

rescale the texels to [tmin, tmax). set tmin=tmax to revert to default behavior using min max of data.

References _tex_max, and _tex_min.

Referenced by main().

const int VSVR::tf_size ( ) const [inline]

accesses the size of the transfer function

References _tf_size.

Referenced by display(), draw_transfer(), load_default_tf(), load_greyscale_tf(), main(), rescale_data(), tex_rescale(), tf_get(), tf_glload(), and tf_set().

void VSVR::tf_set_size ( const int tf_size ) [inline]

changes the size of the transfer function

Parameters:

tf_size

size of the transfer function

References _rescale, and _tf_size.

Referenced by load_default_tf(), and load_greyscale_tf().

void VSVR::tf_set_extern ( float * tf ) [inline]

selects to use a transfer function allocated from another class

Parameters:

tf

is the pointer to the external data, allocated as a size_x*size_y*size_z vector running in x first

References _tf, _tf_extern, and tf_free().

void VSVR::tf_set_intern ( ) [inline]

selects to allocate the transfer function

References _tf, and _tf_extern.

Referenced by load_default_tf(), and load_greyscale_tf().

void VSVR::tf_alloc ( ) [inline]

allocates the transfer function

References _tf, _tf_size, and tf_free().

Referenced by load_default_tf(), and load_greyscale_tf().

void VSVR::tf_free ( ) [inline]

frees the transfer function

References _tf, and _tf_extern.

Referenced by tf_alloc(), tf_set_extern(), and ~VSVR().

void VSVR::load_default_tf ( )

load a default transfer function

References _opacity, a, color_winter, tf_alloc(), tf_set(), tf_set_intern(), tf_set_size(), and tf_size().

Referenced by keyboard(), and main().

void VSVR::load_greyscale_tf ( )

References _opacity, a, g, tf_alloc(), tf_set(), tf_set_intern(), tf_set_size(), and tf_size().

Referenced by keyboard(), and main().

void VSVR::set_opacity ( float opacity ) [inline]

selects to allocate the 3D texture

References _opacity.

Referenced by keyboard(), and main().

void VSVR::tf_get	(	const int	i,
		float &	r,
		float &	g,
		float &245.	7,
		float &442.	2
	)			const `[inline]`

accesses a specific element of the transfer function

Parameters:

	i	element index
	r	returned red component of the color map
	g	returned green component of the color map
	b	returned blue component of the color map
	a	returned transparency of the color map

References _tf, and tf_size().

Referenced by draw_transfer().

void VSVR::tf_set	(	const int	i,
		const float	r,
		const float	g,
		const float 245.	7,
		const float 442.	2
	)			`[inline]`

sets a specific element of the transfer function

Parameters:

	i	element index
	r	red component of the color map
	g	green component of the color map
	b	blue component of the color map
	a	transparency of the color map

References _tf, and tf_size().

Referenced by load_default_tf(), and load_greyscale_tf().

bool VSVR::gl_render ( int nslices = 512 ) [protected]

loads the texture and renders

Parameters:

	nslices	number of slices cut into the texture
	opacity	factor to apply to the transfer function

References _rescale, _tex, _tf, gl_redisplay(), tex_glload(), tex_rescale(), and tf_glload().

Referenced by display().

bool VSVR::gl_redisplay ( int nslices = 512 ) const [protected]

redisplay the texture with the current setting (possibly a different viewpoint)

Parameters:

nslices

number of slices cut into the texture

References _tex, _tf, gl_clip(), gl_set(), gl_unclip(), gl_unset(), tex_ni(), tex_nj(), and tex_nk().

Referenced by display(), and gl_render().

int VSVR::tex_glid ( ) const [inline, protected]

accesses the texture name

References _tex_glid.

float VSVR::wcs_x_to_plot ( const float x ) const [inline, protected]

References _xmax, _xmax_wcs, _xmin, and _xmin_wcs.

Referenced by draw_axes_labels().

float VSVR::wcs_y_to_plot ( const float y ) const [inline, protected]

References _ymax, _ymax_wcs, _ymin, and _ymin_wcs.

Referenced by draw_axes_labels().

float VSVR::wcs_z_to_plot ( const float z ) const [inline, protected]

References _zmax, _zmax_wcs, _zmin, and _zmin_wcs.

Referenced by draw_axes_labels().

void VSVR::gl_string	(	const float	x,
		const float	y,
		const float	z,
		char *	text
	)			const `[protected]`

Draw a string at a given coordinate

Referenced by draw_axes_labels().

float VSVR::suggest_axis_ticks	(	float	fmin,
		float	fmax,
		float *	f0
	)			const `[protected]`

Make a reasonable suggestion for tick-mark spacing

Referenced by draw_axes_labels().

void VSVR::draw_transfer ( ) const [protected]

draw the color bar with the transfer function

draws a bar of the color with transparency

draws a frame of the color without transparency

References a, b, g, tf_get(), and tf_size().

Referenced by display().

void VSVR::draw_axes ( ) const [protected]

draw the coordinate axes

References _xmax, _xmin, _ymax, _ymin, _zmax, _zmin, and draw_axes_labels().

Referenced by display().

void VSVR::draw_axes_labels ( ) const [protected]

draw the axis ticksmakrs and labels

References _xmax, _xmax_wcs, _xmin, _xmin_wcs, _ymax, _ymax_wcs, _ymin, _ymin_wcs, _zmax, _zmax_wcs, _zmin_wcs, gl_string(), suggest_axis_ticks(), wcs_x_to_plot(), wcs_y_to_plot(), and wcs_z_to_plot().

Referenced by draw_axes().

void VSVR::draw_grid ( float * viewer ) const [protected]

draw the grid on the cube sides

References _xmax, _xmin, _ymax, _ymin, _zmax, _zmin, draw_cube_grid(), tex_ni(), tex_nj(), and tex_nk().

Referenced by display().

void VSVR::draw_cube_grid	(	const float	p0[3],
		const float	p1[3],
		const float	p2[3],
		const float	p3[3],
		int	g1,
		int	g2
	)			const `[protected]`

Referenced by draw_grid().

void VSVR::tex_rescale ( ) [protected]

rescale the texels to match the transfer function size

References _rescale, _tex, _tex_max, _tex_min, tex_ni(), tex_nj(), tex_nk(), and tf_size().

Referenced by gl_render().

int VSVR::tex_glload ( ) [protected]

loads the 3D texture

References _tex, _tex_glid, tex_glunload(), tex_ni(), tex_nj(), and tex_nk().

Referenced by gl_render().

int VSVR::tf_glload ( ) const [protected]

loads the transfer function

Parameters:

opacity

factor to apply to the transfer function

References _tf, and tf_size().

Referenced by gl_render().

void VSVR::tex_glunload ( ) [protected]

unloads the 3D texture

References _tex_glid.

Referenced by tex_glload(), and ~VSVR().

void VSVR::tf_glunload ( ) const [protected]

unloads the transfer function

Referenced by ~VSVR().

void VSVR::gl_set ( ) const [protected]

sets the openGL attributes

Referenced by gl_redisplay().

void VSVR::gl_unset ( ) const [protected]

unsets the openGL attributes

Referenced by gl_redisplay().

void VSVR::gl_clip ( ) const [protected]

sets the clipping planes (uses the 6 first)

References tex_ni(), tex_nj(), and tex_nk().

Referenced by gl_redisplay().

void VSVR::gl_unclip ( ) const [protected]

unsets the clipping planes

Referenced by gl_redisplay().

Field Documentation

bool VSVR::_tex_extern [protected]

selects wether to allocate the 3D texture or to use one allocated from another class

Referenced by tex_free(), tex_set_extern(), and tex_set_intern().

int VSVR::_tex_ni [protected]

width of the 3D texture (must be a power of 2)

Referenced by tex_alloc(), tex_get(), tex_ni(), tex_set(), and tex_set_dimensions().

int VSVR::_tex_nj [protected]

depth of the 3D texture (must be a power of 2)

Referenced by tex_alloc(), tex_get(), tex_nj(), tex_set(), and tex_set_dimensions().

int VSVR::_tex_nk [protected]

height of the 3D texture (must be a power of 2)

Referenced by tex_alloc(), tex_nk(), and tex_set_dimensions().

float* VSVR::_tex [protected]

the 3D texture : grid of float values

Referenced by gl_redisplay(), gl_render(), tex_alloc(), tex_free(), tex_get(), tex_glload(), tex_rescale(), tex_set(), tex_set_extern(), tex_set_intern(), and ~VSVR().

float VSVR::_tex_min [protected]

rescale the texture data to from this interval to [0,1). Defaults to minimum of data

Referenced by tex_rescale(), and tex_set_minmax().

float VSVR::_tex_max [protected]

rescale the texture data to from this interval to [0,1) Defaults to maximum of data

Referenced by tex_rescale(), and tex_set_minmax().

bool VSVR::_tf_extern [protected]

selects wether to allocate the transfer function or to use one allocated from another class

Referenced by tf_free(), tf_set_extern(), and tf_set_intern().

int VSVR::_tf_size [protected]

size of the transfer function

Referenced by tf_alloc(), tf_set_size(), and tf_size().

float* VSVR::_tf [protected]

the transfer function : colormap with 4 floats (rgba) per color

Referenced by gl_redisplay(), gl_render(), tf_alloc(), tf_free(), tf_get(), tf_glload(), tf_set(), tf_set_extern(), and tf_set_intern().

float VSVR::_opacity [protected]

the global opacity

Referenced by load_default_tf(), load_greyscale_tf(), and set_opacity().

bool VSVR::_draw_axes [protected]

show the coordinate axes

Referenced by display(), and set_draw_axes().

bool VSVR::_draw_grid [protected]

show the grid

Referenced by display(), and set_draw_grid().

bool VSVR::_draw_tf [protected]

show a colorbar

Referenced by display(), and set_draw_tf().

float VSVR::_xmin [protected]

Referenced by display(), draw_axes(), draw_axes_labels(), draw_grid(), set_world_dimensions(), VSVR(), and wcs_x_to_plot().

float VSVR::_xmax [protected]

boundaries of the cube in opengl coordinates

Referenced by display(), draw_axes(), draw_axes_labels(), draw_grid(), set_world_dimensions(), VSVR(), and wcs_x_to_plot().

float VSVR::_ymin [protected]

Referenced by display(), draw_axes(), draw_axes_labels(), draw_grid(), set_world_dimensions(), VSVR(), and wcs_y_to_plot().

float VSVR::_ymax [protected]

boundaries of the cube in opengl coordinates

Referenced by display(), draw_axes(), draw_axes_labels(), draw_grid(), set_world_dimensions(), VSVR(), and wcs_y_to_plot().

float VSVR::_zmin [protected]

Referenced by display(), draw_axes(), draw_grid(), set_world_dimensions(), VSVR(), and wcs_z_to_plot().

float VSVR::_zmax [protected]

boundaries of the cube in opengl coordinates

Referenced by display(), draw_axes(), draw_axes_labels(), draw_grid(), set_world_dimensions(), VSVR(), and wcs_z_to_plot().

bool VSVR::_force_reload [protected]

need to reload the texture?

Referenced by display(), and force_reload().

float VSVR::_xmin_wcs [protected]

Referenced by draw_axes_labels(), set_axes_dimensions(), VSVR(), and wcs_x_to_plot().

float VSVR::_xmax_wcs [protected]

boundaries of the cube in physical coordinates (for drawing axis labels)

Referenced by draw_axes_labels(), set_axes_dimensions(), VSVR(), and wcs_x_to_plot().

float VSVR::_ymin_wcs [protected]

Referenced by draw_axes_labels(), set_axes_dimensions(), VSVR(), and wcs_y_to_plot().

float VSVR::_ymax_wcs [protected]

boundaries of the cube in physical coordinates (for drawing axis labels)

Referenced by draw_axes_labels(), set_axes_dimensions(), VSVR(), and wcs_y_to_plot().

float VSVR::_zmin_wcs [protected]

Referenced by draw_axes_labels(), set_axes_dimensions(), VSVR(), and wcs_z_to_plot().

float VSVR::_zmax_wcs [protected]

boundaries of the cube in physical coordinates (for drawing axis labels)

Referenced by draw_axes_labels(), set_axes_dimensions(), VSVR(), and wcs_z_to_plot().

bool VSVR::_rescale [private]

needs to rescale

Referenced by gl_render(), tex_rescale(), tex_set_extern(), tex_set_intern(), tex_set_rescale(), and tf_set_size().

unsigned int VSVR::_tex_glid [private]

openGL texture name

Referenced by tex_glid(), tex_glload(), and tex_glunload().