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vpClassifyScanline(3)	    Library Functions Manual	   vpClassifyScanline(3)

NAME
     vpClassifyScanline - incrementally create a preclassified volume from scan-
     lines of scalar data

SYNOPSIS
     #include <volpack.h>

     vpResult
     vpClassifyScanline(vpc, voxels)
	 vpContext *vpc;
	 void *voxels;

ARGUMENTS
     vpc    VolPack context from vpCreateContext.

     voxels 1D array of voxel data.

DESCRIPTION
     vpClassifyScanline  is used to incrementally compute a preclassified volume
     by classifying one scanline of voxels and storing the result in the current
     preclassified volume.

     The voxels argument is a 1D array containing voxels in  the  format  previ-
     ously specified with vpSetVoxelSize and vpSetVoxelField.  vpVolumeSize must
     be  called  to  declare the size of the volume before the first call to vp-
     ClassifyScanline, and the length of the 1D voxel array must be equal to the
     length of the X dimension of the volume.  The 1D voxel array  may	be  ini-
     tialized with vpScanlineNormals or a user-defined function.

     The  voxels  in the array are classified using the current opacity transfer
     function (see vpSetClassifierTable(3)) and appended  to  the  preclassified
     volume  (see  vpClassifyVolume(3)).  Scanlines must be processed in Z-major
     order: all of the scanlines in the Z=0 slice are processed from Y=0 onward,
     then the Z=1 slice is processed, and so on.  When the last scanline in  the
     volume  has  been processed the preclassified data structure is ready to be
     used for rendering.  Rendering is not possible  until  all  scanlines  have
     been processed.

     When  the	first  scanline of a volume is passed to vpClassifyScanline, any
     existing preclassified volume data is destroyed.

ERRORS
     The normal return value is VP_OK.	The following error  return  values  are
     possible:

     VPERROR_BAD_VOXEL
	    The  voxel	size or the voxel fields have not been specified or have
	    been incorrectly specified.

     VPERROR_BAD_CLASSIFIER
	    The opacity transfer function tables have invalid sizes or are asso-
	    ciated with invalid voxel fields or have been incorrectly specified.

SEE ALSO
     VolPack(3),  vpCreateContext(3),  vpSetClassifierTable(3),   vpClassifyVol-
     ume(3), vpClassifyScalars(3)

VolPack 						   vpClassifyScanline(3)

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