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vpRamp(3)		   Library Functions Manual		     vpRamp(3)

NAME
       vpRamp -	initialize an array with a piecewise-linear ramp

SYNOPSIS
       #include	<volpack.h>

       vpResult
       vpRamp(array, stride, num_points, ramp_x, ramp_y)
	   float *array;
	   int stride;
	   int num_points;
	   int *ramp_x;
	   float *ramp_y;

ARGUMENTS
       array  Output array.

       stride Stride from one array element to the next, in bytes.

       num_points
	      Number of	entries	in the input arrays (ramp_x and	ramp_y).

       ramp_x Input array containing indices into array.

       ramp_y Input array containing values to store into array.

DESCRIPTION
       vpRamp is a utility routine for initializing linear arrays of floating-
       point numbers with piecewise-linear ramps.  A ramp is defined by	a  set
       of  (x, y) pairs.  The X	coordinates are	integers that index entries in
       the array argument, and the Y coordinates are floating-point values  to
       store into the array.  Linearly-interpolated Y values are stored	in ar-
       ray elements with indexes in between two	of the X values.

       The values in ramp_x most be strictly increasing.  The stride  argument
       may  be used to skip array elements or to initialize arrays with	a non-
       standard	stride.	 If the	output array is	a simple linear	array of  type
       float then the stride should be sizeof(float).

       This  function  is  useful  for creating	lookup tables used for opacity
       transfer	functions (see vpSetClassifierTable(3))	and shading  functions
       (see vpSetLookupShader(3)).

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

       VPERROR_BAD_VALUE
	      The number of points is less than	one or the X  values  are  not
	      strictly increasing.

SEE ALSO
       VolPack(3)

VolPack								     vpRamp(3)

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

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