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#ifndef lint
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static const char RCSid[] = "$Id: p_func.c,v 2.12 2024/01/07 18:04:16 greg Exp $";
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#endif
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/*
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* p_func.c - routine for procedural patterns.
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*/
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#include "copyright.h"
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#include "ray.h"
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#include "func.h"
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#include "random.h"
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#include "rtotypes.h"
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/*
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* A procedural pattern can either be a brightness or a
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* color function. A brightness function is given as:
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*
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* modifier brightfunc name
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* 2+ bvarname filename xf
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* 0
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* n A1 A2 ..
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*
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* A color function is given as:
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*
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* modifier colorfunc name
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* 4+ rvarname gvarname bvarname filename xf
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* 0
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* n A1 A2 ..
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*
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* A spectral function is given as:
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*
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* modifier specfunc name
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* 2+ sfunc filename xf
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* 0
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* 2+ nmA nmB A3 ..
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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
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* to get from the original coordinates to the current coordinates.
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* For the "specfunc" primitive, sfunc(nm) is a function of wavelength
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* and must be defined from nmA to nmB, and should average to 1 over
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* its range.
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*/
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int
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p_bfunc( /* compute brightness pattern */
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OBJREC *m,
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RAY *r
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)
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{
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double bval;
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MFUNC *mf;
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if (m->oargs.nsargs < 2)
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objerror(m, USER, "bad # arguments");
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mf = getfunc(m, 1, 0x1, 0);
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setfunc(m, r);
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errno = 0;
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bval = evalue(mf->ep[0]);
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if ((errno == EDOM) | (errno == ERANGE)) {
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objerror(m, WARNING, "compute error");
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return(0);
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}
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scalescolor(r->pcol, bval);
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return(0);
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}
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int
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p_cfunc( /* compute color pattern */
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OBJREC *m,
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RAY *r
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)
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{
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SCOLOR scval;
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MFUNC *mf;
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if (m->oargs.nsargs < 4)
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objerror(m, USER, "bad # arguments");
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mf = getfunc(m, 3, 0x7, 0);
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setfunc(m, r);
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errno = 0;
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setscolor(scval, evalue(mf->ep[0]),
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evalue(mf->ep[1]),
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evalue(mf->ep[2]));
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if ((errno == EDOM) | (errno == ERANGE)) {
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objerror(m, WARNING, "compute error");
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return(0);
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}
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smultscolor(r->pcol, scval);
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return(0);
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}
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int
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p_specfunc( /* compute spectral pattern */
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OBJREC *m,
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RAY *r
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)
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{
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SCOLOR scsamp;
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SCOLOR scval;
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double wl, wlmin, wlmax, wlstep;
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int ns, i;
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if ((m->oargs.nsargs < 2) | (m->oargs.nfargs < 2))
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objerror(m, USER, "bad # arguments");
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if (m->oargs.farg[0] < m->oargs.farg[1]) {
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wlmin = m->oargs.farg[0];
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wlmax = m->oargs.farg[1];
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} else {
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wlmin = m->oargs.farg[1];
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wlmax = m->oargs.farg[0];
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}
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if (wlmin < WLPART[3]) wlmin = WLPART[3];
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if (wlmax > WLPART[0]) wlmax = WLPART[0];
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if (wlmin >= wlmax) {
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objerror(m, WARNING, "incompatible wavelength sampling");
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return(0);
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}
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wlstep = (wlmax - wlmin)/(double)MAXCSAMP;
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getfunc(m, 1, 0, 0);
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setfunc(m, r);
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errno = 0;
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ns = (wlmax - wlmin)/wlstep + .1;
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wl = wlmax - .5*wlstep;
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for (i = ns; i-- > 0; wl -= wlstep) {
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double ws = wl + 0.9*(.5-frandom())*wlstep;
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scsamp[i] = funvalue(m->oargs.sarg[0], 1, &ws);
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if ((errno == EDOM) | (errno == ERANGE)) {
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objerror(m, WARNING, "compute error");
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return(0);
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}
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}
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convertscolorcol(scval, scsamp, ns, wlmin, wlmax);
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smultscolor(r->pcol, scval);
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return(0);
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}
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