Class SoOffscreenVolumeRender

  • All Implemented Interfaces:

    public abstract class SoOffscreenVolumeRender
    extends SoNode
    Extract data from an SoVolumeRender. The SoOffscreenVolumeRender node extracts data by rendering one or more volumes (via SoVolumeRender) into a buffer that can then be used for different computation tasks.

    Volumes of interest are specified by a subscenegraph in volumerenderSceneGraph.

    The region to be extracted is the bounding box of the scene graph specified in the bboxSceneGraph field.

    To implement an extraction, the application must derive a new class from SoOffscreenVolumeRender and implement :

    • the boxComputed method. This method is called with parameters that give access to information about the processed box.
    • the getNextSubBox method. This method must return subBox size smaller than getMaxBoxSize. We recommend to request subbox even smaller in order to get more parallelism between extraction processing (done on GPU) and application processing and reduce peak GPU memory resources used.

    The resolution of the extraction is controlled by boxSize field. As extraction is done using GPU techniques, there is a size limit on the boxSize that can be extract in one call. This limit can be retreived through getMaxBoxSize call.


    File format/default:

    SoOffscreenVolumeRender {

      volumerenderSceneGraph NULL
      bboxSceneGraph NULL
      boxSize (64, 64, 64)
      trigger false
      opacityThreshold 0
      components ALPHA

    See Also:
    SoDataSet, SoVolumeData, SoVolumeRender
    • Field Detail

      • volumerenderSceneGraph

        public final SoSFNode volumerenderSceneGraph
        Head of the scene graph that contains one or multiple VolumeRender node to render in 3D off-screen cube.
      • bboxSceneGraph

        public final SoSFNode bboxSceneGraph
        Head of the scene graph that defines the 3D off-screen scene cube to consider in world coordinates.
      • boxSize

        public final SoSFVec3i32 boxSize
        Resolution of the output data in the off-screen box.
      • trigger

        public final SoSFBool trigger
        Setting this field to true will start the off-screen rendering process. This field is set to false when computation is finished. Default is false.
      • opacityThreshold

        public final SoSFFloat opacityThreshold
        During extraction, voxels with an opacity less than the specified value will be ignored Default is 0. Valid range is [0-1].
      • dataSpaceMatrix

        public final SoSFMatrix dataSpaceMatrix
        This transformation is applied on the volume render texture coordinate during the extraction. It allows to change the extraction frame. This matrix is applied on normalized texture coordinates all components are between 0-1 and must be in [0-1] after the transformation. So to inverse an axis, we must apply the following transformation: -1*u+1 (where u is a texture coordinate) and not just a simple negative scale.

        To swap I and J axis, the matrix would be:

         SbMatrix( 0, 1, 0, 0,
                   1, 0, 0, 0,
                   0, 0, 1, 0,
                   0, 0, 0, 1);

        To reverse I axis, the matrix would be:

         SbMatrix(-1, 0, 0, 0,
                   0, 1, 0, 0,
                   0, 0, 1, 0,
                   1, 0, 0, 1);

        To reverse J axis, the matrix would be:

         SbMatrix( 1, 0, 0, 0,
                   0,-1, 0, 0,
                   0, 0, 1, 0,
                   0, 1, 0, 1);

        To reverse K axis, the matrix would be:

         SbMatrix( 1, 0, 0, 0,
                   0, 1, 0, 0,
                   0, 0, -1, 0,
                   0, 0, 1, 1);
    • Method Detail

      • getMaxBoxSize

        public SbVec3i32 getMaxBoxSize()
        Calls getMaxBoxSize((com.openinventor.inventor.misc.SoState)null).
      • ijkToXyzBox

        public SbBox3d ijkToXyzBox​(SbBox3i32 ijkBox)
        Convert ijk box coordinates returned by boxComputed method to the bboxSceneGraph space.
      • synchronousExtraction

        public boolean synchronousExtraction​(SoSceneManager sceneManager)
        Does extraction synchronously, whereas using trigger field will execute extraction on next redraw.

        sceneManager - the scene manager of the viewer scene to be extracted.

        true on success.

      • getMaxBoxSize

        public SbVec3i32 getMaxBoxSize​(SoState state)
        Returns the maximum boxSize that can be extract in one boxComputed for the current state.