Performs direct volume renderings of the volume geometries in the scene. More...

#include <DVRStage.hpp>

Inheritance diagram for LibCarna::presets::DVRStage:

Collaboration diagram for LibCarna::presets::DVRStage:

Public Member Functions
	DVRStage (unsigned int geometryType, unsigned int colorMapResolution=base::ColorMap::DEFAULT_RESOLUTION)
	Instantiates. The created stage will render such base::Geometry scene graph nodes, whose geometry types equal geometryType.

virtual	~DVRStage ()
	Deletes.

virtual void	reshape (base::FrameRenderer &fr, unsigned int width, unsigned int height) override
	Orders this stage to reshape its buffers according to the specified width and height.

virtual void	renderPass (const base::math::Matrix4f &viewTransform, base::RenderTask &rt, const base::Viewport &vp) override
	Triggers the volume rendering.

void	setTranslucency (float translucency)
	Sets the translucency property.

float	translucency () const
	Tells current translucency.

void	setDiffuseLight (float diffuseLight)
	Sets the diffuse light amount to diffuseLight and the ambient light amount to one minus diffuseLight.

float	diffuseLight () const
	Tells the diffuse light amount. The ambient light amount is one minus the diffuse light amount.

bool	isLightingUsed () const
	Tells whether lighting was used during the last rendering. The return value is undefined if nothing was rendered yet.

Public Member Functions inherited from LibCarna::presets::VolumeRenderingStage
	VolumeRenderingStage (unsigned int geometryType)
	Instantiates. The created stage will render such base::Geometry scene graph nodes, whose geometry types equal geometryType.

virtual	~VolumeRenderingStage ()
	Deletes.

void	setSampleRate (unsigned int sampleRate)
	Sets number of slices to be rendered per segment.

unsigned int	sampleRate () const
	Tells number of slices to be rendered per segment.

Public Member Functions inherited from LibCarna::base::GeometryStage< base::Renderable::BackToFront >
	GeometryStage (unsigned int geometryType, unsigned int geometryTypeMask=RenderQueue< base::Renderable::BackToFront >::EXACT_MATCH_GEOMETRY_TYPE_MASK)
	Instantiates s.t. the predefined rendering queue enqueues such LibCarna::base::Geometry scene graph nodes, whose geometry type AND-linked with geometryTypeMask equals the geometryType specified here.

virtual	~GeometryStage ()
	Releases acquired video resources.

virtual void	prepareFrame (Node &root) override
	Called once before each frame.

std::size_t	renderedPassesCount () const
	Tells the number of passes rendered so far since the beginning of the current frame.

GeometryFeatureType::ManagedInterface &	videoResource (GeometryFeatureType &geometryFeature) const
	Interfaces the geometryFeature video resources that were acquired by this rendering stage.

const GeometryFeatureType::ManagedInterface &	videoResource (const GeometryFeatureType &geometryFeature) const

Public Member Functions inherited from LibCarna::base::RenderStage
	RenderStage ()
	Instantiates in enabled-state.

virtual	~RenderStage ()
	Deletes.

void	setViewTransformFixed (bool viewTransformFixed)
	Sets whether the view transform is pass-invariant for the duration of a single frame.

bool	isViewTransformFixed () const
	Tells whether the view transform is pass-invariant for the duration of a single frame.

bool	isInitialized () const
	Tells whether this stage is ready for rendering.

bool	isEnabled () const
	Tells whether this stage is enabled. Disabled stages are not rendered by render tasks.

void	setEnabled (bool)
	Sets whether this stage is enabled. Disabled stages are not rendered by render tasks.

base::FrameRenderer &	renderer ()
	References the renderer this stage belongs to.

const base::FrameRenderer &	renderer () const

void	addRenderStageListener (RenderStageListener &listener)
	Adds listener to the set of listeners this instance notifies in \(\mathcal O\left(\log n\right)\).

void	removeRenderStageListener (RenderStageListener &listener)
	Removes listener from the set of listeners this instance notifies in \(\mathcal O\left(\log n\right)\).

Public Attributes
base::ColorMap	colorMap
	The color map used for the rendering.

Public Attributes inherited from LibCarna::base::GeometryStage< base::Renderable::BackToFront >
const unsigned int	geometryType
	Renders such geometries whose type AND-linked with geometryTypeMask equals this.

const unsigned int	geometryTypeMask
	Renders such geometries whose type AND-linked with this equals geometryType.

Static Public Attributes
static const unsigned int	ROLE_INTENSITIES = 0
	Holds the role that intensity volume data is expected to take when attached to base::Geometry nodes.

static const unsigned int	ROLE_NORMALS = 1
	Holds the role that the normal map is expected to take when attached to base::Geometry nodes.

static const float	DEFAULT_TRANSLUCENCY
	Holds the default translucency.

static const float	DEFAULT_DIFFUSE_LIGHT
	Holds the default diffuse light amount. The ambient light amount is always one minus the diffuse light amount.

Static Public Attributes inherited from LibCarna::presets::VolumeRenderingStage
static const unsigned int	DEFAULT_SAMPLE_RATE = 200
	Holds the default number of slices rendered per segment.

Protected Member Functions
virtual unsigned int	loadVideoResources () override
	Loads video resources when rendering is triggered for the first time. Override this method if you need any additional resources to be loaded, but always call the base implementation.

virtual void	createVolumeSamplers (const std::function< void(unsigned int, base::Sampler *) > &registerSampler) override
	Creates texture samplers for volume textures and uses registerSampler to assign them to the roles that they should be used with.

virtual const base::ShaderProgram &	acquireShader () override
	Acquires the `dvr` shader from the base::ShaderManager.

virtual const std::string &	uniformName (unsigned int role) const override
	Maps ROLE_INTENSITIES to `intensities` and ROLE_NORMALS to `normalMap`.

virtual void	configureShader () override
	Performs custom shader configuration on a per-pass level.

virtual void	configureShader (const base::Renderable &) override
	Computes and uploads the normals transformation matrix.

Protected Member Functions inherited from LibCarna::presets::VolumeRenderingStage
virtual void	render (const base::Renderable &) override
	Renders the renderable.

Protected Member Functions inherited from LibCarna::base::GeometryStage< base::Renderable::BackToFront >
void	activateGLContext () const
	Ensures that the OpenGL context of the hosting LibCarna::base::FrameRenderer is the current one.

virtual void	buildRenderQueues (Node &root, const math::Matrix4f &viewTransform)
	Builds the rendering queues of this stage.

virtual void	rewindRenderQueues ()
	Rewinds the rendering queues of this stage.

virtual void	updateRenderQueues (const math::Matrix4f &viewTransform)
	Recomputes the model-view transforms of the renderables enqueued by this stage.

Additional Inherited Members
Protected Attributes inherited from LibCarna::base::GeometryStage< base::Renderable::BackToFront >
RenderQueue< base::Renderable::BackToFront >	rq
	Holds the predefined rendering queue of this rendering stage.

Detailed Description

Performs direct volume renderings of the volume geometries in the scene.

Usage

The DVRStage constructor takes a geometry type parameter:

dvr = new presets::DVRStage( GEOMETRY_TYPE_VOLUMETRIC );

renderer->appendStage( dvr );

LibCarna::base::RenderStageSequence::appendStage

void appendStage(RenderStage *stage)

Appends stage to the rendering stages sequence.

LibCarna::base::RenderStage::renderer

base::FrameRenderer & renderer()

References the renderer this stage belongs to.

LibCarna::presets::DVRStage

Performs direct volume renderings of the volume geometries in the scene.

Definition DVRStage.hpp:106

The concept of geometry types is explained here.

Note: In the rendering process this stage will usually be inserted after such stages that render opaque geometry, like CuttingPlanesStage and OpaqueRenderingStage.

The DVRStage supports two types of rendering modes: Rendering with lighting enabled and rendering without lighting. In general, lighting produces more sculptural results, but it comes at the cost of additional requirements: Not only the intensity volume must be uploaded to the GPU, but also another 3D texture that maps texture space coordinates to the normal vectors of the surface at a particular location. Depending on the resolution of the data, this might cause noteworthy memory consumption.

Luckily the helpers::VolumeGridHelper class does everything that is needed in order to compute the normal vectors and upload them to the GPU, if it is instructed to do so: Its second type argument is optional and set to void by default. This disables its normal vectors support. Setting it to anything different, like base::NormalMap3DInt8 for example, makes it compute the normal vectors when helpers::VolumeGridHelper::loadIntensities or its computeNormals method are called.

The DVRStage decides which mode to use depending on whether the normal vectors are provided or not.

Without Lighting

The following example code configures the DVRStage s.t. it produces the rendering presented further below:

    dvr->colorMap.writeLinearSegment( base::HUV( -400 ).intensity(), base::HUV(   0 ).intensity(), base::Color:: BLUE_NO_ALPHA, base::Color:: BLUE );
    dvr->colorMap.writeLinearSegment( base::HUV(    0 ).intensity(), base::HUV( 400 ).intensity(), base::Color::GREEN_NO_ALPHA, base::Color::GREEN );
    dvr->setDiffuseLight( 0 );

This gives the following rendering:

exemplary rendering without lighting from code above

Translucency

The translucency scales the opacity values queried from the color map. Assuming that \(\alpha\) was the value from the color map, the translucency \(t \geq 0\) scales the actual opacity to \(\frac{\alpha}{1 + t}\).

With Lighting Enabled

The default translucency is quite high, which is fine for rendering without lighting. You might consider setting it down when rendering with lighting enabled:

    dvr->colorMap.writeLinearSegment( base::HUV( -400 ).intensity(), base::HUV(   0 ).intensity(), base::Color:: BLUE_NO_ALPHA, base::Color:: BLUE );
    dvr->colorMap.writeLinearSegment( base::HUV(    0 ).intensity(), base::HUV( 400 ).intensity(), base::Color::GREEN_NO_ALPHA, base::Color::GREEN );
    dvr->setSampleRate( 1000 );
    dvr->setTranslucency( 2 );

This gives the following rendering:

exemplary rendering with lighting from code above

Author: Leonid Kostrykin

Definition at line 105 of file DVRStage.hpp.

Constructor & Destructor Documentation

◆ DVRStage()

LibCarna::presets::DVRStage::DVRStage	(	unsigned int	geometryType,
		unsigned int	colorMapResolution = `base::ColorMap::DEFAULT_RESOLUTION`
	)

explicit

Instantiates. The created stage will render such base::Geometry scene graph nodes, whose geometry types equal geometryType.

The parameter colorMapResolution determines the resolution of the color map. If your data is 8bit, using 8bit color map is sufficient. If your data is 32bit, you probably also want to use a 32bit color map.

Member Function Documentation

◆ acquireShader()

virtual const base::ShaderProgram & LibCarna::presets::DVRStage::acquireShader ( )

overrideprotectedvirtual

Acquires the dvr shader from the base::ShaderManager.

Implements LibCarna::presets::VolumeRenderingStage.

◆ configureShader() [1/2]

virtual void LibCarna::presets::DVRStage::configureShader ( )

overrideprotectedvirtual

Performs custom shader configuration on a per-pass level.

Implements LibCarna::presets::VolumeRenderingStage.

◆ configureShader() [2/2]

virtual void LibCarna::presets::DVRStage::configureShader ( const base::Renderable & )

overrideprotectedvirtual

Computes and uploads the normals transformation matrix.

Implements LibCarna::presets::VolumeRenderingStage.

◆ createVolumeSamplers()

virtual void LibCarna::presets::DVRStage::createVolumeSamplers ( const std::function< void(unsigned int, base::Sampler *) > & registerSampler )

overrideprotectedvirtual

Creates texture samplers for volume textures and uses registerSampler to assign them to the roles that they should be used with.

Implements LibCarna::presets::VolumeRenderingStage.

◆ loadVideoResources()

virtual unsigned int LibCarna::presets::DVRStage::loadVideoResources ( )

overrideprotectedvirtual

Loads video resources when rendering is triggered for the first time. Override this method if you need any additional resources to be loaded, but always call the base implementation.

Returns: the first texture unit to use for volume textures. The dafault implementation returns base::Texture<0>::SETUP_UNIT +1.

Reimplemented from LibCarna::presets::VolumeRenderingStage.

◆ renderPass()

virtual void LibCarna::presets::DVRStage::renderPass	(	const base::math::Matrix4f &	viewTransform,
		base::RenderTask &	rt,
		const base::Viewport &	vp
	)

overridevirtual

Triggers the volume rendering.

Reimplemented from LibCarna::presets::VolumeRenderingStage.

◆ reshape()

virtual void LibCarna::presets::DVRStage::reshape	(	base::FrameRenderer &	fr,
		unsigned int	width,
		unsigned int	height
	)

overridevirtual

Orders this stage to reshape its buffers according to the specified width and height.

Attention: Always call the base implementaion!

Parameters

fr	references the frame renderer this stage belongs to.
width	is the root viewport width.
height	is the root viewport height.

Reimplemented from LibCarna::base::RenderStage.

◆ setDiffuseLight()

void LibCarna::presets::DVRStage::setDiffuseLight ( float diffuseLight )

Sets the diffuse light amount to diffuseLight and the ambient light amount to one minus diffuseLight.

Precondition: diffuseLight >= 0 && diffuseLight <= 1

This only has an effect if lighting is enabled. If lighting is enabled, setting this to \(0\) virtually disables the lighting.

◆ uniformName()

virtual const std::string & LibCarna::presets::DVRStage::uniformName ( unsigned int role ) const

overrideprotectedvirtual

Maps ROLE_INTENSITIES to intensities and ROLE_NORMALS to normalMap.

Implements LibCarna::presets::VolumeRenderingStage.

Member Data Documentation

◆ colorMap

base::ColorMap LibCarna::presets::DVRStage::colorMap

The color map used for the rendering.

Definition at line 163 of file DVRStage.hpp.

◆ DEFAULT_DIFFUSE_LIGHT

const float LibCarna::presets::DVRStage::DEFAULT_DIFFUSE_LIGHT

static

Holds the default diffuse light amount. The ambient light amount is always one minus the diffuse light amount.

Definition at line 134 of file DVRStage.hpp.

◆ DEFAULT_TRANSLUCENCY

const float LibCarna::presets::DVRStage::DEFAULT_TRANSLUCENCY

static

Holds the default translucency.

Definition at line 128 of file DVRStage.hpp.

◆ ROLE_INTENSITIES

const unsigned int LibCarna::presets::DVRStage::ROLE_INTENSITIES = 0

static

Holds the role that intensity volume data is expected to take when attached to base::Geometry nodes.

Definition at line 117 of file DVRStage.hpp.

◆ ROLE_NORMALS

const unsigned int LibCarna::presets::DVRStage::ROLE_NORMALS = 1

static

Holds the role that the normal map is expected to take when attached to base::Geometry nodes.

Definition at line 123 of file DVRStage.hpp.

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

include/LibCarna/presets/DVRStage.hpp

Public Member Functions

Public Attributes

Static Public Attributes

Protected Member Functions

Additional Inherited Members

Detailed Description

Usage

Without Lighting

Translucency

With Lighting Enabled

Constructor & Destructor Documentation

◆ DVRStage()

Member Function Documentation

◆ acquireShader()

◆ configureShader() [1/2]

◆ configureShader() [2/2]

◆ createVolumeSamplers()

◆ loadVideoResources()

◆ renderPass()

◆ reshape()

◆ setDiffuseLight()

◆ uniformName()

Member Data Documentation

◆ colorMap

◆ DEFAULT_DIFFUSE_LIGHT

◆ DEFAULT_TRANSLUCENCY

◆ ROLE_INTENSITIES

◆ ROLE_NORMALS