RadiancePmap/mx_func.c
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mx_func.c
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			#ifndef lint
			static const char RCSid[] = "$Id: mx_func.c,v 2.9 2014/07/08 18:25:00 greg Exp $";
			#endif
			/*
			* mx_func.c - routine for mixture functions.
			*/

			#include "copyright.h"

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

			/*
			* A mixture function is specified:
			*
			* modifier mixfunc name
			* 4+ foremod backmod varname vfname xf
			* 0
			* n A1 A2 ..
			*
			* Vfname is the name of the file where the variable definition
			* 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
			mx_func( /* compute mixture function */
			OBJREC *m,
			RAY *r
			)
			{
			OBJECT obj;
			int i;
			double coef;
			OBJECT mod[2];
			MFUNC *mf;

			if (m->oargs.nsargs < 4)
			objerror(m, USER, "bad # arguments");
			obj = objndx(m);
			for (i = 0; i < 2; i++)
			if (!strcmp(m->oargs.sarg[i], VOIDID))
			mod[i] = OVOID;
			else if ((mod[i] = lastmod(obj, m->oargs.sarg[i])) == OVOID) {
			sprintf(errmsg, "undefined modifier \"%s\"",
			m->oargs.sarg[i]);
			objerror(m, USER, errmsg);
			}
			mf = getfunc(m, 3, 0x4, 0);
			setfunc(m, r);
			errno = 0;
			coef = evalue(mf->ep[0]);
			if (errno == EDOM \|\| errno == ERANGE) {
			objerror(m, WARNING, "compute error");
			return(0);
			}
			if (raymixture(r, mod[0], mod[1], coef)) {
			if (m->omod != OVOID)
			objerror(m, USER, "inappropriate modifier");
			return(1);
			}
			return(0);
			}