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p_func.c
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	#ifndef lint
	static const char RCSid[] = "$Id: p_func.c,v 2.8 2014/07/08 18:25:00 greg Exp $";
	#endif
	/*
	* p_func.c - routine for procedural patterns.
	*/

	#include "copyright.h"

	#include "ray.h"
	#include "func.h"
	#include "rtotypes.h"

	/*
	* A procedural pattern can either be a brightness or a
	* color function. A brightness function is given as:
	*
	* modifier brightfunc name
	* 2+ bvarname filename xf
	* 0
	* n A1 A2 ..
	*
	* A color function is given as:
	*
	* modifier colorfunc name
	* 4+ rvarname gvarname bvarname filename xf
	* 0
	* n A1 A2 ..
	*
	* Filename is the name of the file where the variable definitions
	* can be found. The list of real arguments can be accessed by
	* definitions in the file. The xf is a transformation
	* to get from the original coordinates to the current coordinates.
	*/


	int
	p_bfunc( /* compute brightness pattern */
	OBJREC *m,
	RAY *r
	)
	{
	double bval;
	MFUNC *mf;

	if (m->oargs.nsargs < 2)
	objerror(m, USER, "bad # arguments");
	mf = getfunc(m, 1, 0x1, 0);
	setfunc(m, r);
	errno = 0;
	bval = evalue(mf->ep[0]);
	if (errno == EDOM \|\| errno == ERANGE) {
	objerror(m, WARNING, "compute error");
	return(0);
	}
	scalecolor(r->pcol, bval);
	return(0);
	}


	int
	p_cfunc( /* compute color pattern */
	OBJREC *m,
	RAY *r
	)
	{
	COLOR cval;
	MFUNC *mf;

	if (m->oargs.nsargs < 4)
	objerror(m, USER, "bad # arguments");
	mf = getfunc(m, 3, 0x7, 0);
	setfunc(m, r);
	errno = 0;
	setcolor(cval, evalue(mf->ep[0]),
	evalue(mf->ep[1]),
	evalue(mf->ep[2]));
	if (errno == EDOM \|\| errno == ERANGE) {
	objerror(m, WARNING, "compute error");
	return(0);
	}
	multcolor(r->pcol, cval);
	return(0);
	}