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greg |
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/* Copyright (c) 1986 Regents of the University of California */
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#ifndef lint
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static char SCCSid[] = "$SunId$ LBL";
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#endif
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/*
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* t_func.c - routine for procedural textures.
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*
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* 4/8/86
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*/
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#include "ray.h"
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/*
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* A procedural texture perturbs the surface normal
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* at the point of intersection with an object. It has
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* the form:
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*
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* modifier texfunc name
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* 4+ xvarname yvarname zvarname filename xf
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* 0
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* n A1 A2 ..
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*
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* Filename is the name of the file where the variable definitions
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* can be found. The list of real arguments can be accessed by
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* definitions in the file. The xf is a transformation to get
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* from the original coordinates to the current coordinates.
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*/
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typedef struct {
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struct {
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double sca; /* scale factor */
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double xfm[4][4]; /* transformation matrix */
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} fore, back;
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} XFORM;
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t_func(m, r) /* compute texture for ray */
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register OBJREC *m;
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register RAY *r;
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{
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#define mxf ((XFORM *)m->os)
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extern double varvalue();
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extern int errno;
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FVECT disp;
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register int i;
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register char **sa;
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if (m->oargs.nsargs < 4)
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objerror(m, USER, "bad # arguments");
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sa = m->oargs.sarg;
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if (mxf == NULL) {
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mxf = (XFORM *)malloc(sizeof(XFORM));
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if (mxf == NULL)
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goto memerr;
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mxf->fore.sca = 1.0;
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setident4(mxf->fore.xfm);
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if (xf(mxf->fore.xfm, &mxf->fore.sca,
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m->oargs.nsargs-4, sa+4) != m->oargs.nsargs-4)
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objerror(m, USER, "bad transform");
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if (mxf->fore.sca < 0.0)
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mxf->fore.sca = -mxf->fore.sca;
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mxf->back.sca = 1.0;
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setident4(mxf->back.xfm);
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invxf(mxf->back.xfm, &mxf->back.sca,
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m->oargs.nsargs-4, sa+4);
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if (mxf->back.sca < 0.0)
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mxf->back.sca = -mxf->back.sca;
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}
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setmap(m, r, mxf->back.sca, mxf->back.xfm);
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if (!vardefined(sa[0]))
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loadfunc(sa[3]);
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errno = 0;
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for (i = 0; i < 3; i++)
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disp[i] = varvalue(sa[i]);
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if (errno) {
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objerror(m, WARNING, "compute error");
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return;
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}
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if (mxf->fore.xfm == NULL)
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for (i = 0; i < 3; i++)
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r->pert[i] += disp[i];
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else
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for (i = 0; i < 3; i++)
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r->pert[i] += ( disp[0]*mxf->fore.xfm[0][i] +
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disp[1]*mxf->fore.xfm[1][i] +
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disp[2]*mxf->fore.xfm[2][i] )
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/ mxf->fore.sca;
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return;
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memerr:
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error(SYSTEM, "out of memory in t_func");
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#undef mxf
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}
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