vlVolume::SlicedVolume Class Reference

An actor encapsulating all the geometry and effects needed to directly render a volume using viewport aligned slices. More...

#include <SlicedVolume.hpp>

Inheritance diagram for vlVolume::SlicedVolume:

List of all members.

Public Member Functions
	SlicedVolume ()
	Constructor.
void	update (int, vl::Camera *camera, vl::Real)
	Virtual function used to update or animate an Actor during the rendering.
virtual void	updateUniforms (vl::Camera *camera)
	Updates the uniforms used by the vl::GLSLProgram to render the volume each time the update() function is called.
void	setSliceCount (int count)
	Defines the number of slices used to render the volume: more slices generate a better rendering.
int	sliceCount () const
	Returns the number of slices used to render the volume.
vl::Geometry *	geometry ()
	Returns the vl::Geometry associated to a SlicedVolume actor.
const vl::Geometry *	geometry () const
	Returns the vl::Geometry associated to a SlicedVolume actor.
vl::Effect *	effect ()
	Returns the vl::Effect associated to a SlicedVolume actor.
const vl::Effect *	effect () const
	Returns the vl::Effect associated to a SlicedVolume actor.
void	setBox (const vl::AABB &box)
	Defines the dimensions of the box enclosing the volume.
const vl::AABB &	box () const
	Defines the dimensions of the box enclosing the volume.
const vl::fvec3 *	texCoords () const
	Returns the texture coordinates assigned to each of the 8 box corners.
vl::fvec3 *	texCoords ()
	Returns the texture coordinates assigned to each of the 8 box corners.
void	generateTextureCoordinates (const vl::ivec3 &size)
	Generates a default set of texture coordinates based on the give texture dimensions.
void	generateTextureCoordinates (int width, int height, int depth)
	Generates a default set of texture coordinates based on the give texture dimensions.
void	setVolumeImage (vl::Image *volume)
	Defines the image containing the volume to be rendered.
const vl::Image *	transferFunction () const
	Returns the 1D image used as transfer function for the volume rendering.
vl::Image *	transferFunction ()
	Returns the 1D image used as transfer function for the volume rendering.
void	setTransferFunction (vl::Image *tfunc)
	Sets the 1D image used as transfer function for the volume rendering. Pass NULL to remove the transfer function.
const vl::Light *	light () const
	Returns the light used to illuminate the volume.
vl::Light *	light ()
	Returns the light used to illuminate the volume.
void	setLight (vl::Light *light)
	Defines the light used to illuminate the volume.
const vl::GLSLProgram *	glslProgram () const
	Returns the GLSL program used for IF_LUMINANCE volume images.
vl::GLSLProgram *	glslProgram ()
	Returns the GLSL program used for IF_LUMINANCE volume images.
Static Public Member Functions
static vl::ref< vl::Image >	genRGBAVolume (vl::Image *data, vl::Image *trfunc, const vl::fvec3 &light_dir, bool alpha_from_data=true)
	Generates an RGBA image that can be passed to setVolumeImage() based on the given data source and transfer function.
static vl::ref< vl::Image >	genRGBAVolume (vl::Image *data, vl::Image *trfunc, bool alpha_from_data=true)
	Generates an RGBA image that can be passed to setVolumeImage() based on the given data source and transfer function.
Protected Attributes
int	mSliceCount
vl::ref< vl::Geometry >	mGeometry
vl::ref< vl::Effect >	mEffect
vl::AABB	mBox
vl::fmat4	mCache
vl::fvec3	mTexCoord [8]
vl::ref< vl::Image >	mTransferFunction
vl::ref< vl::Light >	mLight
vl::ref< vl::GLSLProgram >	mGLSLProgram

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Detailed Description

An actor encapsulating all the geometry and effects needed to directly render a volume using viewport aligned slices.

Pictures from the Volume Rendering tutorial.

Using the SlicedVolume class is extremely simple, see below. See also the App_VolumeRendering.hpp example.

By default the constructor installs the following shaders /glsl/volume_luminance_light.fs and /glsl/volume_luminance_light.vs and sets the val_threshold uniform variable to 0.5f.

You can change the GLSLProgram settings in the following way:

 glslProgram()->detachAllShaders();
 glslProgram()->attachShader( new vl::GLSLFragmentShader("/mypath/my_fragment_shader.fs") );
 glslProgram()->attachShader( new vl::GLSLVertexShader("/mypath/my_vertex_shader.fs") );
 glslProgram()->gocUniform("my_uniform")->setUniform(value);

You can also reimplement the updateUniforms() method to update your own uniform variables before every rendering frame.

Using an IF_RGBA volume (no GLSL)

 vl::ref<vlVolume::SlicedVolume> volume = new SlicedVolume;
 // loads an IF_RGBA volume (no transfer function is needed in this case)
 vl::ref<vl::Image> rgba_img = vl::loadImage("myvolume.dat"); 
 // installs the IF_RGBA volume
 volume->setVolumeImage(rgba_img.get());
 // disable GLSL shader
 volume->setTransferFunction(NULL);

Generating an IF_RGBA volume from an IF_LUMINANCE volume + transfer function (no GLSL)

 vl::ref<vlVolume::SlicedVolume> volume = new SlicedVolume;
 // loads an IF_LUMINANCE volume
 vl::ref<vl::Image> img      = vl::loadImage("myvolume.dat"); 
 // generates a transfer function
 vl::ref<vl::Image> trfunc   = vl::Image::makeColorSpectrum(128, vlut::black, vlut::blue, vlut::green, vlut::yellow, vlut::red);
 // computes an IF_RGBA volume using the transfer function and with lighting
 vl::ref<vl::Image> rgba_img = vlVolume::SlicedVolume::genRGBAVolume(img.get(), trfunc.get(), vl::fvec3(1.0f,1.0f,0.0f));
 // installs the IF_RGBA volume
 volume->setVolumeImage(rgba_img.get());
 // disable GLSL shader
 volume->setTransferFunction(NULL);

Using IF_LUMINANCE volume + transfer function with GLSL (with dynamic Blinn-Phong lighting)

 vl::ref<vlVolume::SlicedVolume> volume = new SlicedVolume;
 // generates and install a transfer function to be used with an IF_LUMINANCE volume.
 vl::ref<vl::Image> trfunc = vl::Image::makeColorSpectrum(128, vlut::black, vlut::blue, vlut::green, vlut::yellow, vlut::red);
 // setTransferFunction() also enables the GLSL shader
 volume->setTransferFunction(trfunc.get());
 // loads and install an IF_LUMINANCE volume.
 vl::ref<vl::Image> img = vl::loadImage("myvolume.dat");
 volume->setVolumeImage(img.get());

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Constructor & Destructor Documentation

SlicedVolume::SlicedVolume

(

)

Constructor.

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Member Function Documentation

void vlVolume::SlicedVolume::update	(	int	,
		vl::Camera *	,
		vl::Real
	)			[virtual]

Virtual function used to update or animate an Actor during the rendering.

Parameters:

	lod	the LOD (level of detail) currently selected for the rendering.
	camera	the camera used for the current rendering.
	cur_t	the current animation time.

Note:

• is called after the actor resulted to be visible
• is called only once per frame
• is called before setting up the rendering states

See also:

• ActorRenderingCallback
• renderingCallbacks()

Reimplemented from vl::Actor.

void SlicedVolume::updateUniforms

(

vl::Camera *

camera

)

[virtual]

Updates the uniforms used by the vl::GLSLProgram to render the volume each time the update() function is called.

You can reimplement this function in order to setup your own uniform variable for your GLSLProgram.

The default implementation of this function updates the following two uniforms:

• light_position Light position in object space, used to compute Blinn-Phong lighting in /glsl/volume_luminance_light.fs
• eye_position Camera position in object space, used to compute Blinn-Phong lighting in /glsl/volume_luminance_light.fs

void vlVolume::SlicedVolume::setSliceCount

(

int

count

)

[inline]

Defines the number of slices used to render the volume: more slices generate a better rendering.

int vlVolume::SlicedVolume::sliceCount

(

)

const [inline]

Returns the number of slices used to render the volume.

vl::Geometry* vlVolume::SlicedVolume::geometry

(

)

[inline]

Returns the vl::Geometry associated to a SlicedVolume actor.

const vl::Geometry* vlVolume::SlicedVolume::geometry

(

)

const [inline]

Returns the vl::Geometry associated to a SlicedVolume actor.

vl::Effect* vlVolume::SlicedVolume::effect

(

)

[inline]

Returns the vl::Effect associated to a SlicedVolume actor.

Reimplemented from vl::Actor.

const vl::Effect* vlVolume::SlicedVolume::effect

(

)

const [inline]

Returns the vl::Effect associated to a SlicedVolume actor.

Reimplemented from vl::Actor.

void SlicedVolume::setBox

(

const vl::AABB &

box

)

Defines the dimensions of the box enclosing the volume.

const vl::AABB& vlVolume::SlicedVolume::box

(

)

const [inline]

Defines the dimensions of the box enclosing the volume.

const vl::fvec3* vlVolume::SlicedVolume::texCoords

(

)

const [inline]

Returns the texture coordinates assigned to each of the 8 box corners.

vl::fvec3* vlVolume::SlicedVolume::texCoords

(

)

[inline]

Returns the texture coordinates assigned to each of the 8 box corners.

void SlicedVolume::generateTextureCoordinates

(

const vl::ivec3 &

size

)

Generates a default set of texture coordinates based on the give texture dimensions.

The texture coordinate generated by this function should be used with TexParameter wrap mode vl::TPW_REPEAT, ie:.

vl::ref<vl::Texture> texture = new vl::Texture;
texture->getTexParameter()->setWrapS(vl::TPW_REPEAT);
texture->getTexParameter()->setWrapT(vl::TPW_REPEAT);
texture->getTexParameter()->setWrapR(vl::TPW_REPEAT);

void vlVolume::SlicedVolume::generateTextureCoordinates	(	int	width,
		int	height,
		int	depth
	)			[inline]

Generates a default set of texture coordinates based on the give texture dimensions.

void SlicedVolume::setVolumeImage

(

vl::Image *

volume

)

Defines the image containing the volume to be rendered.

This function also generates a 3D texture based on the given image and generates an appropriate set of texture coordinates.

const vl::Image* vlVolume::SlicedVolume::transferFunction

(

)

const [inline]

Returns the 1D image used as transfer function for the volume rendering.

vl::Image* vlVolume::SlicedVolume::transferFunction

(

)

[inline]

Returns the 1D image used as transfer function for the volume rendering.

void SlicedVolume::setTransferFunction

(

vl::Image *

tfunc

)

Sets the 1D image used as transfer function for the volume rendering. Pass NULL to remove the transfer function.

Selecting a transfer function != NULL automatically enables the GLSL shader returned by glslProgram().

Call setTransferFunction(NULL) to disable the GLSL program. Based on the img format an appropriate rendering method is selected:

• If tfunc is NULL then it is assumed that the image set by setVolumeImage() contains already the appropriate colors and alpha values as a result of a transfer function and/or lighting computations (see genRGBAVolume()). This is the preferred method for legacy hardware as it does not require GLSL support but can require 4 times more memory and cannot perform realtime-animated lighting.
• If tfunc is non-NULL then the image set by setVolumeImage() should have IF_LUMINANCE format() and contains the raw volume data. A GLSL program is used in order to execute the transfer function and the lighting computations. In this case the tranfer function tfunc is used. This method requires GLSL support, needs less memory and can perform realtime-animated Blinn-Phong lighting.

const vl::Light* vlVolume::SlicedVolume::light

(

)

const [inline]

Returns the light used to illuminate the volume.

vl::Light* vlVolume::SlicedVolume::light

(

)

[inline]

Returns the light used to illuminate the volume.

void vlVolume::SlicedVolume::setLight

(

vl::Light *

light

)

[inline]

Defines the light used to illuminate the volume.

const vl::GLSLProgram* vlVolume::SlicedVolume::glslProgram

(

)

const [inline]

Returns the GLSL program used for IF_LUMINANCE volume images.

vl::GLSLProgram* vlVolume::SlicedVolume::glslProgram

(

)

[inline]

Returns the GLSL program used for IF_LUMINANCE volume images.

ref< Image > SlicedVolume::genRGBAVolume	(	vl::Image *	data,
		vl::Image *	trfunc,
		const vl::fvec3 &	light_dir,
		bool	alpha_from_data = true
	)			[static]

Generates an RGBA image that can be passed to setVolumeImage() based on the given data source and transfer function.

Parameters:

	data	The vl::Image used as the volume data source. It must have format() equal to IF_LUMINANCE and type() equal to IT_UNSIGNED_BYTE, IT_UNSIGNED_SHORT or IT_UNSIGNED_FLOAT.
	trfunc	An 1D vl::Image used as transfer function that is used to assign to each value in data an RGBA quadruplets in the new image. The vl::Image pointed by trfunc must mast have type() IT_UNSIGNED_BYTE and format() IF_RGBA.
	light_dir	The direction of the light in object space.
	alpha_from_data	If set to true the alpha channel of the generated image will be taken from data otherwise from the transfer function.

ref< Image > SlicedVolume::genRGBAVolume	(	vl::Image *	data,
		vl::Image *	trfunc,
		bool	alpha_from_data = true
	)			[static]

Generates an RGBA image that can be passed to setVolumeImage() based on the given data source and transfer function.

Parameters:

	data	The vl::Image used as the volume data source. It must have format() equal to IF_LUMINANCE and type() equal to IT_UNSIGNED_BYTE, IT_UNSIGNED_SHORT or IT_UNSIGNED_FLOAT.
	trfunc	An 1D vl::Image used as transfer function that is used to assign to each value in data an RGBA quadruplets in the new image. The vl::Image pointed by trfunc must mast have type() IT_UNSIGNED_BYTE and format() IF_RGBA.
	alpha_from_data	If set to true the alpha channel of the generated image will be taken from data otherwise from the transfer function.

Unlike genRGBAVolume(vl::Image* data, vl::Image* trfunc, const vl::fvec3& light_dir, bool alpha_from_data=true) this function does not compute lighting.

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Member Data Documentation

int vlVolume::SlicedVolume::mSliceCount [protected]

vl::ref<vl::Geometry> vlVolume::SlicedVolume::mGeometry [protected]

vl::ref<vl::Effect> vlVolume::SlicedVolume::mEffect [protected]

Reimplemented from vl::Actor.

vl::AABB vlVolume::SlicedVolume::mBox [protected]

vl::fmat4 vlVolume::SlicedVolume::mCache [protected]

vl::fvec3 vlVolume::SlicedVolume::mTexCoord[8] [protected]

vl::ref<vl::Image> vlVolume::SlicedVolume::mTransferFunction [protected]

vl::ref<vl::Light> vlVolume::SlicedVolume::mLight [protected]

vl::ref<vl::GLSLProgram> vlVolume::SlicedVolume::mGLSLProgram [protected]

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

• E:/VisualizationLibrary/Visualization_Library_SDK/src/vlVolume/SlicedVolume.hpp
• E:/VisualizationLibrary/Visualization_Library_SDK/src/vlVolume/SlicedVolume.cpp