Class SoColorMap

  • All Implemented Interfaces:

    public class SoColorMap
    extends SoNode
    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.


    • 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.


    The following example shows how to apply an indexed texture on a geometry node:

     SoColorMap colorMap = new SoColorMap();
       colorMap.predefinedColorMap.setValue( SoColorMap.PredefinedColorMaps.TEMPERATURE );
       colorMap.min.setValue( -1000 );
       colorMap.max.setValue( 20000 );
     SoIndexedTexture2 indexedTexture = new SoIndexedTexture2();
       indexedTexture.imageIndex.setValue(size, SoSFArray.DataTypes.SIGNED_SHORT, data); 
     root.addChild( colorMap );
     root.addChild( indexedTexture );
     root.addChild( geometry ); 

    File format/default:

    ColorMap {

      min 0
      max 0
      predefinedColorMap TEMPERATURE
      colorMapFormat RGB_ALPHA
      colorMap 0

    Action behavior:

    SoGLRenderAction, SoCallbackAction
    Sets: SoColorMapElement

    See Also:
    SoIndexedTexture2, SoLightModel
    • Field Detail

      • min

        public final SoSFFloat 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:

      • predefinedColorMap

        public final SoSFEnum<SoColorMap.PredefinedColorMaps> predefinedColorMap
        Use this field to load predefined color maps. . Default is TEMPERATURE. All predefined color maps have 256 entries.


        NOTE: In the images above the checkerboard pattern shows through where the color map alpha (opacity) value is less than 1.0.

        If it is set to NONE, the fields below must be set.

      • colorMapFormat

        public final SoSFEnum<SoColorMap.ColorMapFormats> colorMapFormat
        Indicates the format of the color map (number of color components). . 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".

      • colorMap

        public final SoMFFloat 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.
      • interpolation

        public final SoSFEnum<SoColorMap.Interpolations> interpolation
        The colormap interpolation type. These types determine the method used for color map texture filtering. . Default is NEAREST.

        Open Inventor 9.4.2

    • Constructor Detail

      • SoColorMap

        public SoColorMap()
    • Method Detail

      • getNumColor

        public int getNumColor()
        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)
      • hasTransparency

        public boolean hasTransparency()
        Returns true if the current color map contains alpha values less than 1. false means the color map is completely opaque.