SoColorMap Class Reference
[Textures]

Class for indexed texture color map More...

#include <Inventor/nodes/SoColorMap.h>

Inheritance diagram for SoColorMap:

Public Types
enum	ColorMapFormat { LUMINANCE, ALPHA, LUMINANCE_ALPHA, RGB, RGB_ALPHA }
enum	PredefinedColorMap { NONE, GRAY, TEMPERATURE, PHYSICS, STANDARD, GLOW, BLUE_RED, SEISMIC, BLUE_WHITE_RED, INTENSITY, LABEL_256, VOLREN_RED, VOLREN_GREEN, AIRWAY, AIRWAY_SURFACES, INTENSITY_REVERSED }
enum	Interpolation { NEAREST, LINEAR }
Public Member Functions
virtual SoType	getTypeId () const
	SoColorMap ()
unsigned int	getNumColor () const
SbBool	hasTransparency () const
Static Public Member Functions
static SoType	getClassTypeId ()
Public Attributes
SoSFFloat	min
SoSFFloat	max
SoSFEnum	predefinedColorMap
SoSFEnum	colorMapFormat
SoMFFloat	colorMap
SoSFEnum	interpolation

Detailed Description

Class for indexed texture color map

This class describes the association between values of the SoIndexedTexture2 node and colors.

The data value coming from the SoIndexedTexture2 node is used as an index into the color map defined by the colorMap field or the predefinedColorMap field.

The predefinedColorMap field allows you to specify a predefined color map or using value NONE, that the color map is contained in the colorMap field.

The min and max fields define the range of the data values that will actually be used. The color map is modified such that only data values ranging from min to max will be mapped to the color map. The figure below illustrates the effects of these fields:

The SoColorMap node acts like an SoShaderProgram with an SoFragmentShader. Standard Open Inventor operations on textures will be disabled on all subsequent nodes, thus using an SoTexture2 node or multitexturing after this node will not give the expected result.

NOTE:

The SoColorMap node must be inserted before the SoIndexedTexture2.
This node puts the color map in the next available texture unit, so this unit must not be used for any other purpose in your application. On hardware which doesn't support ARB_fragment_program but supports EXT_paletted_texture , the next available texture unit is not used and thus remains available for use by the application.
If your graphics hardware does not support the ARB_fragment_program or the EXT_paletted_texture OpenGL extension, this node has no effect.
SoColorMap is intended to be used with a SoIndexedTexture2 node. However, without an SoIndexedTexture2 node, the color map will still be applied on the geometry, but without indexation. To specify a color map for volume rendering, see SoTransferFunction.

EXAMPLE

      SoColorMap *colorMap = new SoColorMap();
        colorMap->predefinedColorMap = SoColorMap::TEMPERATURE;  
        colorMap->min.setValue( -1000 );        
        colorMap->max.setValue( 20000 );        
      SoIndexedTexture2 *indexedTexture = new SoIndexedTexture2();
        indexedTexture->imageIndex.setValue(size, SoSFArray2D::SIGNED_SHORT, data); 
      root->addChild( colorMap );
      root->addChild( indexedTexture );
      root->addChild( geometry );

FILE FORMAT/DEFAULT

min	0
max	0
predefinedColorMap	TEMPERATURE
colorMapFormat	RGB_ALPHA
colorMap	0

ACTION BEHAVIOR

SoGLRenderAction

SoCallbackAction

SoColorMapElement

Member Enumeration Documentation

enum SoColorMap::ColorMapFormat

Color map format.

Enumerator:

LUMINANCE	(1 float)
ALPHA	(1 float)
LUMINANCE_ALPHA	(2 floats)
RGB	(3 floats)
RGB_ALPHA	(4 floats)

enum SoColorMap::Interpolation

The colormap interpolation type.

These types determine the method used for color map texture filtering.

Enumerator:

NEAREST	Nearest-neighbor interpolation.
LINEAR	Linear interpolation.

enum SoColorMap::PredefinedColorMap

Predefined color map.

Enumerator:

NONE	None.
GRAY	Gray (Default).
TEMPERATURE	Temperature.
PHYSICS	Physics.
STANDARD	Standard.
GLOW	Glow.
BLUE_RED	Blue red.
SEISMIC	Seismic.
BLUE_WHITE_RED	Blue white red.
INTENSITY	Intensity.
LABEL_256	256 labels
VOLREN_RED	VolRenRed.
VOLREN_GREEN	VolRenGreen.
AIRWAY	Airway.
AIRWAY_SURFACES	Airway surfaces.
INTENSITY_REVERSED	Intensity reversed.

Constructor & Destructor Documentation

SoColorMap::SoColorMap ( )

Constructor.

Member Function Documentation

static SoType SoColorMap::getClassTypeId ( ) [static]

Returns the type identifier for this class.

Reimplemented from SoNode.

unsigned int SoColorMap::getNumColor ( ) const

This convenience method returns the number of colors in the color map (ie: colorMap.getNum()/Number of components or 256 if a predefined color map is used).

virtual SoType SoColorMap::getTypeId ( ) const [virtual]

Returns the type identifier for this specific instance.

Reimplemented from SoNode.

SbBool SoColorMap::hasTransparency ( ) const

Returns TRUE if the current color map contains alpha values less than 1.

FALSE means the color map is completely opaque.

Member Data Documentation

SoMFFloat SoColorMap::colorMap

Array of floats in range [0,1].

The number of floats depends on colorMapFormat. It is equal to the number of colors defined multiplied by the number of components per color. For example, for an RGBA color map of length n, there should be 4*n float values in the field. If a predefined color map is specified, the values of this field are not used.

SoSFEnum SoColorMap::colorMapFormat

Indicates the format of the color map (number of color components).

Use enum ColorMapFormat. Default is RGB_ALPHA.

LUMINANCE means one component per color for a grayscale color map.

ALPHA means one alpha component per color.

LUMINANCE_ALPHA means two components per color, luminance and alpha. In such a case the colorMap float array contains a list of two floats. Index 0 is luminance, index 1 is alpha, index 2 is luminance, index 3 is alpha and so on.

RGB means three components per color, ordered red first, then green and blue.

RGB_ALPHA means four components per color, ordered red first, then green, blue, and alpha.

An alpha value equal to zero means "fully transparent", an alpha value equal to one means "opaque".

SoSFEnum SoColorMap::interpolation

The colormap interpolation type.

These types determine the method used for color map texture filtering. Use enum Interpolation. Default is NEAREST.

NOTE: field available since Open Inventor 9.4.2

SoSFFloat SoColorMap::max

See min.

SoSFFloat SoColorMap::min

This field allow to remap the color map such that only data values ranging from min to max will be mapped to the color map.

min and max must be between minValue and maxValue of the corresponding SoIndexedTexture2 node.

Values less than min and greater than max will be set to colorMap[0] and colorMap[colorMap.getNum()-1] respectively. If min is less than the minimum of the indexed texture minValue , it will be clamped to this minimum. If max is greater than the maximum of the indexed texture maxValue , it will be clamped to this maximum. When min and max are equal to 0 (the default), the entire range of data values is used.

Setting (min,max) to (64,192) while the predefined STANDARD color map is selected and in the case of a UNSIGNED_BYTE indexed texture will make the color map as shown: