Documentation for vtkLookupTable

vtkLookupTable - map scalar values into colors or colors to scalars; generate color table

Description:

vtkLookupTable is an object that is used by mapper objects to map scalar values into rgba (red-green-blue-alpha transparency) color specification, or rgba into scalar values. The color table can be created by direct insertion of color values, or by specifying hue, saturation, value, and alpha range and generating a table. This class is designed as a base class for derivation by other classes. The Build(), MapValue(), and SetTableRange() methods are virtual and may require overloading in subclasses.

Caveats:

vtkLookupTable is a reference counted object. Therefore, you should always use operator "new" to construct new objects. This procedure will avoid memory problems (see text).

See Also:

vtkLogLookupTable vtkWindowLevelLookupTable

Methods:

	void vtkLookupTable (int ,int )
	void vtkLookupTable ()
	int Allocate (int ,int )
	void Build ()
	static vtkLookupTable *New ()
	const char *GetClassName ()
	void PrintSelf (unknown & ,vtkIndent )
	void SetNumberOfColors (int )
	int GetNumberOfColors ()
	void SetTableRange (float )
	void SetTableRange (float ,float )
	float *GetTableRange ()
	void SetHueRange (float ,float )
	void SetHueRange (float *)
	float *GetHueRange ()
	void SetSaturationRange (float ,float )
	void SetSaturationRange (float *)
	float *GetSaturationRange ()
	void SetValueRange (float ,float )
	void SetValueRange (float *)
	float *GetValueRange ()
	void SetAlphaRange (float ,float )
	void SetAlphaRange (float *)
	float *GetAlphaRange ()
	unsigned char *MapValue (float )
	void SetNumberOfTableValues (int )
	void SetTableValue (int ,float )
	void SetTableValue (int ,float ,float ,float ,float )
	float *GetTableValue (int )
	void GetTableValue (int ,float )
	unsigned char *GetPointer (const int )
	unsigned char *WritePointer (const int ,const int )

Detailed Method Descriptions:

Construct with range=(0,1); and hsv ranges set up for rainbow color table (from red to blue).

void vtkLookupTable (int ,int )

Allocate a color table of specified size.

int Allocate (int ,int )

Generate lookup table from hue, saturation, value, alpha min/max values. Table is built from linear ramp of each value.

void Build ()

Set the number of colors in the lookup table. Use this method before building the lookup table. Use SetNumberOfTableValues() to change the table size after the lookup table has been built.

	void SetNumberOfColors (int )
	int GetNumberOfColors ()

Set/Get the minimum/maximum scalar values for scalar mapping. Scalar values less than minimum range value are clamped to minimum range value. Scalar values greater than maximum range value are clamped to maximum range value.

	void SetTableRange (float )
	void SetTableRange (float ,float )
	float *GetTableRange ()

Set the range in hue (using automatic generation). Hue ranges between (0,1).

	void SetHueRange (float ,float )
	void SetHueRange (float *)
	float *GetHueRange ()

Set the range in saturation (using automatic generation). Saturation ranges between (0,1).

	void SetSaturationRange (float ,float )
	void SetSaturationRange (float *)
	float *GetSaturationRange ()

Set the range in value (using automatic generation). Value ranges between (0,1).

	void SetValueRange (float ,float )
	void SetValueRange (float *)
	float *GetValueRange ()

Set the range in alpha (using automatic generation). Alpha ranges from (0,1).

	void SetAlphaRange (float ,float )
	void SetAlphaRange (float *)
	float *GetAlphaRange ()

Map one value through the lookup table.

unsigned char *MapValue (float )

Specify the number of values (i.e., colors) in the lookup table. This method simply allocates memory and prepares the table for use with SetTableValue(). It differs from Build() method in that the allocated memory is not initialized according to HSVA ramps.

void SetNumberOfTableValues (int )

Directly load color into lookup table. Use [0,1] float values for color component specification. Make sure that you've either used the Build() method or used SetNumberOfTableValues() prior to using this method.

void SetTableValue (int ,float )

Directly load color into lookup table. Use [0,1] float values for color component specification.

void SetTableValue (int ,float ,float ,float ,float )

Return a rgba color value for the given index into the lookup table. Color components are expressed as [0,1] float values.

	float *GetTableValue (int )
	void GetTableValue (int ,float )

Get pointer to color table data. Format is array of unsigned char r-g-b-a-r-g-b-a...

unsigned char *GetPointer (const int )

Get pointer to data. Useful for direct writes into object. MaxId is bumped by number (and memory allocated if necessary). Id is the location you wish to write into; number is the number of rgba values to write.

unsigned char *WritePointer (const int ,const int )