Fragment shaders

VolumeViz GLSL fragment shaders API. More...

Functions
bool	VVizIsClipped (vec3 tCoord)
	Customizes the SoVolumeShader::CLIPPING_FUNCTION shader stage.
bool	VVizIsClippedByROI (in VVizDataSetId dataset, in vec3 texCoord)
	Returns true if the given coordinate is clipped by a ROI applied on the given dataset.
void	VVizClipVoxel ()
	Applies clipping when using an SoVolumeClippingGroup or SoUniformGridClipping node.
VVIZ_DATATYPE	VVizCombineData (in vec3 dataCoord)
	SoVolumeShader::DATA_COMBINE_FUNCTION function.
vec4	VVizComputeFragmentColor (in VVizDataSetId dataset, in vec3 rayDir, inout VVizVoxelInfo voxelInfoFront, in VVizVoxelInfo voxelInfoBack, in int mask)
	SoVolumeShader::FRAGMENT_COMPUTE_COLOR function.
vec3	VVizComputeCoordinates (const vec3 dataCoord)
	Compute new coordinates from input coordinates.
vec3	VVizComputeCoordinates (in VVizDataSetId dataset, const vec3 dataCoord)
	Compute new coordinates from input coordinates.
vec4	VVizOverOperator (vec4 underCol, vec4 overCol)
	Blend 2 colors using the over operator, result color is not alpha premultiplied.
float	VVizGetLuminance (VVIZ_DATATYPE data)
	Compute the luminance of a voxel value.
vec3	VVizGetNearestCoord (in VVizVoxelInfo voxelInfo)
	Returns virtual coordinates of nearest voxel center, taking in account current voxel resolution.
vec3	VVizGetNearestCoord (in VVizDataSetId dataset, in VVizVoxelInfo voxelInfo)
	Returns virtual coordinates of nearest voxel center, taking in account current voxel resolution.
vec3	VVizComputePreintegratedGradient (vec3 tcoord0, vec3 tcoord1)
	Returns the gradient at the center of the two slices.
vec3	VVizComputeNormal (vec3 view, vec3 grad)
	Returns the current normal.
vec3	VVizComputeNormal (vec3 tcoordVirt)
	Compute normal in surface of 2D shapes (slices, volumeGeometry, volumeSkin, hzighfield) at given coordinates.
vec3	VVizComputeNormal (in VVizDataSetId dataset, vec3 tcoordVirt)
	Compute normal in surface of 2D shapes (slices, volumeGeometry, volumeSkin, hzighfield) at given coordinates.
vec4	VVizComputeIsoMaterial (VVizDataSetId tex, in VVizVoxelInfo voxelInfoFront, in VVizVoxelInfo voxelInfoBack, int maskId)
	Returns the color of the lighted pixel belonging to the isosurface.
vec4	VVizComputePreIntegrated (VVIZ_DATATYPE sf, VVIZ_DATATYPE sb)
	Convert the volume data values (sf, sb) to a color by lookup in the pre-integrated table.
vec4	VVizComputeVolumeRendering (VVIZ_DATATYPE sf)
	Returns the conversion of the volume data value sf to color by lookup in the colormap.
vec4	VVizComputeVolumeRenderingLighting (in vec4 col, in vec3 normal, in float gradLength)
	Add lighting to the color col.
vec4	VVizComputeVolumeRenderingLighting (in VVizDataSetId dataset, in vec4 col, in vec3 normal, in float gradLength)
	Add lighting to the color col.
vec4	VVizComputePreintegratedLighting (in vec4 col, in vec3 normal, in float gradLength)
	Add lighting to the color col in the case of pre-integrated rendering.
vec4	VVizComputePreintegratedLighting (in VVizDataSetId dataset, in vec4 col, in vec3 normal, in float gradLength)
	Add lighting to the color col in the case of pre-integrated rendering.
vec3	VVizComputeViewVec ()
	Returns the current viewing vector in the model space of the default dataset.
vec3	VVizComputeViewVec (in VVizDataSetId dataset)
	Returns the current viewing vector in the model space of the given dataset.
void	VVizComputeGradientCommon (in vec3 tcoordFront, in vec3 tcoordBack, out vec3 gradient, out vec3 normal)
	Computes gradient and normal values at the given texture coordinates.
void	VVizComputeGradientCommon (VVizDataSetId dataset, in vec3 tcoordFront, in vec3 tcoordBack, out vec3 gradient, out vec3 normal)
	Computes gradient and normal values for the given dataset at the given texture coordinates.
VVIZ_DATATYPE	VVizGetData (in VVizDataSetId dataset, in vec3 dataCoord)
	SoVolumeShader::GET_DATA_FUNCTION function.
VVIZ_DATATYPE	VVizGetRawData (in VVizDataSetId dataset, in vec3 dataCoord)
	Default SoVolumeShader::GET_DATA_FUNCTION function.
int	VVizGetMask (in vec3 tcoord)
	Returns the mask value at the given texture coordinate.
void	VVizOutputColor (vec4 color)
	This function sends the final fragment color to OpenGL.
vec4	VVizTransferFunction (in VVIZ_DATATYPE voxelValue, in int Id)
	1D transfer function.
vec4	VVizTransferFunction (in VVIZ_DATATYPE frontVoxelValue, in VVIZ_DATATYPE backVoxelValue, in int Id)
	Pre-integrated transfer function.

Detailed Description

VolumeViz GLSL fragment shaders API.

Function Documentation

VVizClipVoxel()

void VVizClipVoxel

(

)

Applies clipping when using an SoVolumeClippingGroup or SoUniformGridClipping node.

If no SoUniformGridClipping or SoVolumeClippingGroup nodes are present in the scene graph, this function will have no effect.

Must be called in a custom FRAGMENT_MAIN shader only.

VVizCombineData()

VVIZ_DATATYPE VVizCombineData

(

in vec3

dataCoord

)

SoVolumeShader::DATA_COMBINE_FUNCTION function.

Applications can replace this method to customize the SoVolumeShader::DATA_COMBINE_FUNCTION shader stage.

Parameters

dataCoord

Uniform data coordinate in the volume space of the default DataSet (see VVizGetDefaultDataSet()).

Returns

voxel data value.

VVizComputeCoordinates() [1/2]

vec3 VVizComputeCoordinates

(

const vec3

dataCoord

)

Compute new coordinates from input coordinates.

This method is used to support rectilinear coordinates or custom projection. It computes voxel coordinates and must be used instead of gl_TexCoord[0].xyz. If not used, texture coordinates may not be clamped, scaled, etc... as necessary in order to have correct rendering.

The parameter usually is gl_TexCoord[0].xyz (in slicing mode only). The returned coordinate is in general directly passed to VVizCombineData method.

Parameters

dataCoord

Coordinates of point, in the normalized volume space of the default DataSet.

Returns

Projected coord if requested, returns dataCoord by default.

VVizComputeCoordinates() [2/2]

vec3 VVizComputeCoordinates	(	in VVizDataSetId	dataset,
		const vec3	dataCoord
	)

Compute new coordinates from input coordinates.

This method is used to support rectilinear coordinates or custom projection. It computes voxel coordinates and must be used instead of gl_TexCoord[0].xyz. If not used, texture coordinates may not be clamped, scaled, etc... as necessary in order to have correct rendering.

The parameter usually is gl_TexCoord[0].xyz (in slicing mode only). The returned coordinate is in general directly passed to VVizCombineData method.

Parameters

dataset	Dataset id
dataCoord	Coordinates of point, in the normalized volume space of dataset.

Returns

Projected coord if requested, returns dataCoord by default.

VVizComputeFragmentColor()

vec4 VVizComputeFragmentColor	(	in VVizDataSetId	dataset,
		in vec3	rayDir,
		inout VVizVoxelInfo	voxelInfoFront,
		in VVizVoxelInfo	voxelInfoBack,
		in int	mask
	)

SoVolumeShader::FRAGMENT_COMPUTE_COLOR function.

Applications can replace this method to customize the SoVolumeShader::FRAGMENT_COMPUTE_COLOR shader stage.
Note: This version of the method is only used by the SoVolumeRender node.

Parameters

dataset	Dataset id
rayDir	ray Direction in the volume space of dataset.
voxelInfoFront	Voxel info of front slice.
voxelInfoBack	Voxel info of back slice
mask	Current mask Id

VVizComputeGradientCommon() [1/2]

void VVizComputeGradientCommon	(	in vec3	tcoordFront,
		in vec3	tcoordBack,
		out vec3	gradient,
		out vec3	normal
	)

Computes gradient and normal values at the given texture coordinates.

Only available for Volume Rendering because the gradient is computed using texel neighbors in the 3D texture.

This method is for the default DataSet. For a specific dataset, see VVizComputeGradientCommon(in VVizDataSetId, in vec3, in vec3, out vec3, out vec3)

VVizComputeGradientCommon() [2/2]

void VVizComputeGradientCommon	(	VVizDataSetId	dataset,
		in vec3	tcoordFront,
		in vec3	tcoordBack,
		out vec3	gradient,
		out vec3	normal
	)

Computes gradient and normal values for the given dataset at the given texture coordinates.

Only available for Volume Rendering because the gradient is computed using texel neighbors in the 3D texture.

VVizComputeIsoMaterial()

vec4 VVizComputeIsoMaterial	(	VVizDataSetId	tex,
		in VVizVoxelInfo	voxelInfoFront,
		in VVizVoxelInfo	voxelInfoBack,
		int	maskId
	)

Returns the color of the lighted pixel belonging to the isosurface.

sf and sb are usually the volume data which have the texture coordinate gl_TexCoord[0] and gl_TexCoord[1] computed by VVizComputeFrontSliceTexCoord and VVizComputeBackSliceTexCoord. If there is no isosurface between sf and sb, a transparent pixel will be returned. Lighting is computed with the first directional light found in the scene graph.
Because it needs a special texture, this function can only be used with SoVolumeIsosurface.

VVizComputeNormal() [1/3]

vec3 VVizComputeNormal	(	in VVizDataSetId	dataset,
		vec3	tcoordVirt
	)

Compute normal in surface of 2D shapes (slices, volumeGeometry, volumeSkin, hzighfield) at given coordinates.

Normal is returned in eye space. If bump mapping is currently enabled, the normal corresponding to bump effect will be returned.

VVizComputeNormal() [2/3]

vec3 VVizComputeNormal

(

vec3

tcoordVirt

)

Compute normal in surface of 2D shapes (slices, volumeGeometry, volumeSkin, hzighfield) at given coordinates.

Normal is returned in eye space. If bump mapping is currently enabled, the normal corresponding to bump effect will be returned.

This method is only for the default DataSet. For a specific dataset, see VVizComputeNormal(in VVizDataSetId, vec3)

VVizComputeNormal() [3/3]

vec3 VVizComputeNormal	(	vec3	view,
		vec3	grad
	)

Returns the current normal.

VVizComputePreIntegrated()

vec4 VVizComputePreIntegrated	(	VVIZ_DATATYPE	sf,
		VVIZ_DATATYPE	sb
	)

Convert the volume data values (sf, sb) to a color by lookup in the pre-integrated table.

The pre-integrated table is a precomputed table which gives an approximation of the volume rendering integral between two slices.
Because it needs a special texture, this function can only be used with SoVolumeRenderingQuality.

VVizComputePreintegratedGradient()

vec3 VVizComputePreintegratedGradient	(	vec3	tcoord0,
		vec3	tcoord1
	)

Returns the gradient at the center of the two slices.

VVizComputePreintegratedLighting() [1/2]

vec4 VVizComputePreintegratedLighting	(	in vec4	col,
		in vec3	normal,
		in float	gradLength
	)

Add lighting to the color col in the case of pre-integrated rendering.

col is usually the result of VVizComputePreintegrated. The difference with the VVizComputeVolumeRenderingLighting function is that the normal used for lighting is at the middle of the space between the front and the back slice. Lighting is computed with the first directional light found in the scene graph.
Because it needs a special texture, this function can only be used with SoVolumeRenderingQuality.

VVizComputePreintegratedLighting() [2/2]

vec4 VVizComputePreintegratedLighting	(	in VVizDataSetId	dataset,
		in vec4	col,
		in vec3	normal,
		in float	gradLength
	)

Add lighting to the color col in the case of pre-integrated rendering.

col is usually the result of VVizComputePreintegrated. The difference with the VVizComputeVolumeRenderingLighting function is that the normal used for lighting is at the middle of the space between the front and the back slice. Lighting is computed with the first directional light found in the scene graph.
Because it needs a special texture, this function can only be used with SoVolumeRenderingQuality.

VVizComputeViewVec() [1/2]

vec3 VVizComputeViewVec

(

)

Returns the current viewing vector in the model space of the default dataset.

VVizComputeViewVec() [2/2]

vec3 VVizComputeViewVec

(

in VVizDataSetId

dataset

)

Returns the current viewing vector in the model space of the given dataset.

VVizComputeVolumeRendering()

vec4 VVizComputeVolumeRendering

(

VVIZ_DATATYPE

sf

)

Returns the conversion of the volume data value sf to color by lookup in the colormap.

VVizComputeVolumeRenderingLighting() [1/2]

vec4 VVizComputeVolumeRenderingLighting	(	in vec4	col,
		in vec3	normal,
		in float	gradLength
	)

Add lighting to the color col.

col is usually the result of VVizComputeVolumeRendering.

VVizComputeVolumeRenderingLighting() [2/2]

vec4 VVizComputeVolumeRenderingLighting	(	in VVizDataSetId	dataset,
		in vec4	col,
		in vec3	normal,
		in float	gradLength
	)

Add lighting to the color col.

col is usually the result of VVizComputeVolumeRendering.

VVizGetData()

VVIZ_DATATYPE VVizGetData	(	in VVizDataSetId	dataset,
		in vec3	dataCoord
	)

SoVolumeShader::GET_DATA_FUNCTION function.

Applications can replace this method to customize the SoVolumeShader::GET_DATA_FUNCTION shader stage.

NOTE: On the GPU, voxel values are always returned as a normalized value in the range 0..1. If the actual voxel value is needed, the shader function must compute that value using the current data range (see SoDataRange). The application must explicitly pass the current data range to the shader function as a uniform parameter.

Parameters

dataset	The dataset to read
dataCoord	Uniform data coordinates in volume space.

Returns

voxel data value.

VVizGetLuminance()

float VVizGetLuminance

(

VVIZ_DATATYPE

data

)

Compute the luminance of a voxel value.

Parameters

data	value to convert

Returns

Luminance of data.

VVizGetMask()

int VVizGetMask

(

in vec3

tcoord

)

Returns the mask value at the given texture coordinate.

If there is no SoVolumeMask, the returned value is the id of the transfer function on the state.

VVizGetNearestCoord() [1/2]

vec3 VVizGetNearestCoord	(	in VVizDataSetId	dataset,
		in VVizVoxelInfo	voxelInfo
	)

Returns virtual coordinates of nearest voxel center, taking in account current voxel resolution.

This can be used to avoid having interpolation issues by taking the true value of voxel.

VVizGetNearestCoord() [2/2]

vec3 VVizGetNearestCoord

(

in VVizVoxelInfo

voxelInfo

)

Returns virtual coordinates of nearest voxel center, taking in account current voxel resolution.

This can be used to avoid having interpolation issues by taking the true value of voxel.

VVizGetRawData()

VVIZ_DATATYPE VVizGetRawData	(	in VVizDataSetId	dataset,
		in vec3	dataCoord
	)

Default SoVolumeShader::GET_DATA_FUNCTION function.

Method to access dataset, that can be used by VVizGetData custom implementation. It may apply different interpolation (linear, cubix, trilinear, multi-sample12) depending on SoVolumeRenderingQuality and SoVolumeRender nodes setup.

NOTE: On the GPU, voxel values are always returned as a normalized value in the range 0..1. If the actual voxel value is needed, the shader function must compute that value using the current data range (see SoDataRange). The application must explicitly pass the current data range to the shader function as a uniform parameter.

Parameters

dataset	The dataset to read
dataCoord	uniform data coordinates in volume space.

Returns

voxel data value

VVizIsClipped()

bool VVizIsClipped

(

vec3

tCoord

)

Customizes the SoVolumeShader::CLIPPING_FUNCTION shader stage.

Parameters

tCoord

Coordinate in the volume space of the default DataSet (see VVizGetDefaultDataSet())

Returns

TRUE if given tCoord should be clipped.

VVizIsClippedByROI()

bool VVizIsClippedByROI	(	in VVizDataSetId	dataset,
		in vec3	texCoord
	)

Returns true if the given coordinate is clipped by a ROI applied on the given dataset.

The given texture coordinate is defined in the texture coordinate space of the given dataset. e.g. the coordinates (0.5, 0.5, 0.5) correspond to the center of the given dataset.

VVizOutputColor()

void VVizOutputColor

(

vec4

color

)

This function sends the final fragment color to OpenGL.

It should be used instead of directly setting gl_FragColor, in order to allow VolumeViz to do final manipulation of the color.

Should be used at the end of FRAGMENT_MAIN shader only.

Parameters

color

the color to render.

VVizOverOperator()

vec4 VVizOverOperator	(	vec4	underCol,
		vec4	overCol
	)

Blend 2 colors using the over operator, result color is not alpha premultiplied.

Parameters

underCol	First color to blend.
overCol	Second color to blend.

Returns

Blended color.

VVizTransferFunction() [1/2]

vec4 VVizTransferFunction	(	in VVIZ_DATATYPE	frontVoxelValue,
		in VVIZ_DATATYPE	backVoxelValue,
		in int	Id
	)

Pre-integrated transfer function.

Parameters

frontVoxelValue	Input voxel data value of the front slice.
backVoxelValue	Input voxel data value of the back slice.
Id	of the transfer function to use.

Returns

Color of the value based on the transfer function id

VVizTransferFunction() [2/2]

vec4 VVizTransferFunction	(	in VVIZ_DATATYPE	voxelValue,
		in int	Id
	)

1D transfer function.

Parameters

voxelValue	Input voxel data value
Id	of the transfer function to use.

Returns

Color of the value based on the transfer function id