RadiancePmap/t_func.c
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t_func.c
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			#ifndef lint
			static const char RCSid[] = "$Id: t_func.c,v 2.10 2014/07/08 18:25:00 greg Exp $";
			#endif
			/*
			* t_func.c - routine for procedural textures.
			*/

			#include "copyright.h"

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

			/*
			* A procedural texture perturbs the surface normal
			* at the point of intersection with an object. It has
			* the form:
			*
			* modifier texfunc name
			* 4+ xvarname yvarname zvarname 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
			t_func( /* compute texture for ray */
			OBJREC *m,
			RAY *r
			)
			{
			FVECT disp;
			double d;
			MFUNC *mf;
			int i;

			if (m->oargs.nsargs < 4)
			objerror(m, USER, "bad # arguments");
			mf = getfunc(m, 3, 0x7, 1);
			setfunc(m, r);
			errno = 0;
			for (i = 0; i < 3; i++) {
			disp[i] = evalue(mf->ep[i]);
			if (errno == EDOM \|\| errno == ERANGE) {
			objerror(m, WARNING, "compute error");
			return(0);
			}
			}
			if (mf->fxp != &unitxf)
			multv3(disp, disp, mf->fxp->xfm);
			if (r->rox != NULL) {
			multv3(disp, disp, r->rox->f.xfm);
			d = 1.0 / (mf->fxp->sca * r->rox->f.sca);
			} else
			d = 1.0 / mf->fxp->sca;
			VSUM(r->pert, r->pert, disp, d);
			return(0);
			}