Class SoMaterial

  • All Implemented Interfaces:

    public class SoMaterial
    extends SoNode
    Surface material definition node. This node defines the current surface material properties for all subsequent shapes. SoMaterial sets several components of the current material during traversal. The ambientColor, diffuseColor, emissiveColor, specularColor and shininess fields are interpreted according to the classic OpenGL lighting model. The transparency field is effectively the inverse of "opacity" or "alpha value".

    If lighting is turned off (SoLightModel set to BASE_COLOR), only the diffuse color and transparency fields are used to render geometry.

    Multiple values can be specified for the diffuseColor and transparency fields. Different shapes interpret materials with multiple values differently. To bind materials to shapes, use an SoMaterialBinding node.

    Several other nodes can be used to set diffuse color and transparency for geometry.

    If the other color values are not needed, these nodes use a little less memory than an SoMaterial node, especially if multiple color values are specified. Generally SoVertexProperty is the most efficient mechanism and may provide better performance than using SoMaterial. Note that for these nodes transparency is set as "alpha value" (inverse of transparency).

    • Diffuse color (only) can also be specified using an SoBaseColor node.
    • Diffuse color and transparency can also be specified using an SoPackedColor node.
    • Diffuse color and transparency can also be specified for polygonal geometry using the orderedRGBA field of SoVertexProperty.

    Lighting and material RGB values:

    The color components specified for lights mean something different than for materials. For a light, the numbers correspond to a percentage of full intensity for each color. If the R, G, and B values for a light's color are all 1.0, the light is the brightest possible white. If the values are 0.5, the color is still white, but only at half intensity, so it appears gray. If R=G=1 and B=0 (full red and green with no blue), the light appears yellow. The intensity can also be modulated using the SoLight.intensity field.

    For materials, the numbers correspond to the reflected percentages of those colors. So if R=1, G=0.5, and B=0 for a material, that material reflects all the incoming red light, half the incoming green, and none of the incoming blue light. In other words, if an OpenGL light has components (LR, LG, LB), and a material has corresponding components (MR, MG, MB), then, ignoring all other reflectivity effects, the light that arrives at the eye is given by (LR*MR, LG*MG, LB*MB). As a result, for example, shining a pure blue light on a pure red cone has no visible effect.

    Similarly, if you have two lights that send (R1, G1, B1) and (R2, G2, B2) to the eye, the components are added, giving (R1+R2, G1+G2, B1+B2). If any of the sums are greater than 1 (corresponding to a color brighter than the hardware can display), the component is clamped to 1.

    Override material:

    To force all geometry following/below this node to use specific color and transparency values, call the setOverride() method with true. Overriding the diffuse color and transparency overrides the color and transparency values in other nodes including SoPackedColor and SoVertexProperty. This can be useful, for example, to highlight a selected object.

    It is also possible to override only a subset of the SoMaterial fields. If, for example, you only want to override the diffuse color, but not the other values, call setIgnored(true) on the fields that you do not want to override. But note that this selective override technique only works on other SoMaterial nodes! For SoPackedColor and SoVertexProperty, the diffuseColor and transparency values are bound together and cannot be overridden separately.


    The default transparency algorithm is NO_SORT. To get a nice appearance for transparent objects you must change this to another value, for example, OPAQUE_FIRST or SORTED_PIXEL, using the setTransparencyType method in the Viewer class. See SoGLRenderAction for a discussion of transparency algorithms and rendering order.

    VolumeViz shapes:

    For scalar (non-RGBA) volumes, the color and alpha value of a voxel is affected by two nodes. SoMaterial's diffuseColor field specifies the "base" color and alpha values for all voxels. SoTransferFunction specifies color and alpha values based on the voxel value. The final voxel color and alpha (before lighting and other effects) is computed by multiplying these two color and alpha values. The default material is 0.8, 0.8, 0.8, 1 (fully opaque gray). The 0.8 value for R, G and B allows lighting to increase the brightness of the voxel. For slice rendering without lighting, the application may want to set the material to 1, 1, 1, 1 so that only the SoTransferFunction affects the voxel color and alpha. Effectively the material alpha value (aka transparency) is a "global" multiplier that can be used to increase or decrease the transparency of all voxels in the volume.

    File format/default:

    Material {

      ambientColor 0.2 0.2 0.2
      diffuseColor 0.8 0.8 0.8
      specularColor 0 0 0
      emissiveColor 0 0 0
      shininess 0.2
      transparency 0

    Action behavior:

    SoGLRenderAction, SoCallbackAction
    Sets the ambient color, the diffuse color, the specular color, the emissive color, the shininess, and the transparency of the current material. Sets: SoMaterialElement

    See Also:
    SoBaseColor, SoLightModel, SoMaterialBinding, SoPackedColor, SoVertexProperty
    • Field Detail

      • ambientColor

        public final SoMFColor ambientColor
        Ambient color of the surface. Default is 0.2 0.2 0.2.

        Ambient reflectance affects the overall color of the object. Because diffuse reflectance is brightest where an object is directly illuminated, ambient reflectance is most noticeable where an object receives no direct illumination. An object's total ambient reflectance is affected by the global ambient light (see SoEnvironment) and ambient light from individual light sources. Like diffuse reflectance, ambient reflectance is not affected by the position of the camera.

      • diffuseColor

        public final SoMFColor diffuseColor
        Diffuse color(s) of the surface. Default is 0.8 0.8 0.8.

        Diffuse reflectance plays the most important role in determining the appearance of an object. It's affected by the color of the incident light(s) and the angle of each incident light relative to the object's normal direction. (It's most intense where the incident light falls perpendicular to the surface.) The position of the camera doesn't affect diffuse reflectance at all.

      • specularColor

        public final SoMFColor specularColor
        Specular color of the surface. Default is 0 0 0.

        Specular reflection from an object produces highlights. Unlike ambient and diffuse reflection, the amount of specular reflection does depend on the location of the camera - it's brightest along the direct angle of reflection. To see this, imagine looking at a metallic ball outdoors in the sunlight. As you move your head, the highlight created by the sunlight moves with you to some extent. However, if you move your head too much, you lose the highlight entirely.

        This field specifies the color of the reflected light. The shininess field controls the size and brightness of the highlight.

      • emissiveColor

        public final SoMFColor emissiveColor
        Emissive color of the surface. Default is 0 0 0.

        Emissive color makes an object appear to be giving off light of that color, independent of any lights (or lack of lights) in the scene. It can be useful for highlighting selected objects in the scene.

      • shininess

        public final SoMFFloat shininess
        Shininess coefficient of the surface. Values can range from 0.0 to 1.0. Default is 0.2.

        The dot product of the vector reflected by the surface normal and the inverted light vector is raised to the "Shininess" power. The higher the shininess number, the smaller the resulting specular highlight turns out to be.

      • transparency

        public final SoMFFloat transparency
        Transparency value(s) of the surface. Values can range from 0.0 for opaque surfaces to 1.0 for completely transparent surfaces. Default is 0 (opaque).

        Transparency is the inverse of "opacity" or "alpha" value.

    • Constructor Detail

      • SoMaterial

        public SoMaterial()
        Creates a material node with default settings.