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vpSetVoxelSize(3)	   Library Functions Manual	     vpSetVoxelSize(3)

NAME
       vpSetVoxelSize -	define the size	of a voxel

SYNOPSIS
       #include	<volpack.h>

       vpResult
       vpSetVoxelSize(vpc,	    bytes_per_voxel,	     num_voxel_fields,
	       num_shade_fields, num_classify_fields)
	   vpContext *vpc;
	   int bytes_per_voxel;
	   int num_voxel_fields;
	   int num_shade_fields;
	   int num_classify_fields;

ARGUMENTS
       vpc    VolPack context from vpCreateContext.

       bytes_per_voxel
	      Size of one voxel	in bytes.

       num_voxel_fields
	      Number of	fields in a voxel.

       num_shade_fields
	      Number of	voxel fields that are arguments	to the	shading	 func-
	      tion.

       num_classify_fields
	      Number  of voxel fields that are arguments to the	opacity	trans-
	      fer function.

DESCRIPTION
       vpSetVoxelSize is used to define	the size in bytes and  the  number  of
       fields  in  a  voxel.   Each voxel field	is analogous to	a field	in a C
       structure and the contents of each  field  is  user-defined.   See  the
       vpSetVoxelField	function (vpSetVoxelField(3)) for setting the size and
       offset of each field.  vpSetVoxelSize should be called before vpSetVox-
       elField and before any functions	that access the	contents of a voxel.

       Typically,  some	of the voxel fields are	used as	arguments to a shading
       function	and some (possibly the same) fields are	used as	 arguments  to
       an opacity transfer function (for classification).  The fields that are
       used for	shading	should come first, i.e.	they should have the  smallest
       offsets,	 followed by any fields	that are only used for classification.
       The classification fields can then be stripped off to save space	during
       the precomputation stage	for the	fast rendering algorithm.  The parame-
       ter num_shade_fields indicates the number of fields (starting from  the
       first) that must	not be stripped	off.

       The  parameter  num_clsfy_fields	 indicates  the	total number of	fields
       that are	used as	parameters to the opacity  transfer  function.	 These
       fields  do  not	necessarily have to be contiguous, although any	fields
       that are	not also used for shading should be the	 last  fields  in  the
       voxel.

       If the call to vpSetVoxelSize succeeds, any existing precomputed	volume
       data structures in the context are destroyed.

STATE VARIABLES
       The current voxel size parameters can be	retrieved with	the  following
       state	variable    codes    (see    vpGeti(3)):   VP_BYTES_PER_VOXEL,
       VP_VOXEL_FIELD_COUNT, VP_SHADE_FIELD_COUNT, VP_CLASSIFY_FIELD_COUNT.

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

       VPERROR_LIMIT_EXCEEDED
	      The  number  of  voxel  fields exceeds the implementation	limit.
	      This limit can be	increased by editing volpack.h and recompiling
	      the library.

       VPERROR_BAD_VALUE
	      Either num_clsfy_fields or num_shade_fields is out of range.

SEE ALSO
       VolPack(3), vpCreateContext(3), vpSetVoxelField(3)

VolPack							     vpSetVoxelSize(3)

NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | STATE VARIABLES | ERRORS | SEE ALSO

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