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#ifndef lint
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static const char RCSid[] = "$Id: m_brdf.c,v 2.43 2024/12/13 19:05:03 greg Exp $";
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#endif
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/*
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* Shading for materials with arbitrary BRDF's
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*/
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#include "copyright.h"
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#include "ray.h"
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#include "ambient.h"
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#include "data.h"
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#include "source.h"
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#include "otypes.h"
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#include "rtotypes.h"
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#include "func.h"
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#include "pmapmat.h"
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/*
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* Arguments to this material include the color and specularity.
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* String arguments include the reflection function and files.
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* The BRDF is currently used just for the specular component to light
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* sources. Reflectance values or data coordinates are functions
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* of the direction to the light source. (Data modification functions
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* are passed the source direction as args 2-4.)
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* We orient the surface towards the incoming ray, so a single
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* surface can be used to represent an infinitely thin object.
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*
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* Arguments for MAT_PFUNC and MAT_MFUNC are:
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* 2+ func funcfile transform
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* 0
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* 4+ red grn blu specularity A5 ..
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*
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* Arguments for MAT_PDATA and MAT_MDATA are:
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* 4+ func datafile funcfile v0 .. transform
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* 0
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* 4+ red grn blu specularity A5 ..
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*
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* Arguments for MAT_TFUNC are:
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* 2+ func funcfile transform
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* 0
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* 6+ red grn blu rspec trans tspec A7 ..
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*
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* Arguments for MAT_TDATA are:
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* 4+ func datafile funcfile v0 .. transform
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* 0
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* 6+ red grn blu rspec trans tspec A7 ..
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*
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* Arguments for the more general MAT_BRTDF are:
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* 10+ rrefl grefl brefl
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* rtrns gtrns btrns
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* rbrtd gbrtd bbrtd
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* funcfile transform
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* 0
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* 9+ rdf gdf bdf
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* rdb gdb bdb
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* rdt gdt bdt A10 ..
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*
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* In addition to the normal variables available to functions,
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* we define the following:
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* NxP, NyP, NzP - perturbed surface normal
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* RdotP - perturbed ray dot product
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* CrP, CgP, CbP - perturbed material color (or pattern)
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*/
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typedef struct {
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OBJREC *mp; /* material pointer */
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RAY *pr; /* intersected ray */
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DATARRAY *dp; /* data array for PDATA, MDATA or TDATA */
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SCOLOR mcolor; /* material (or pattern) color */
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SCOLOR rdiff; /* diffuse reflection */
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SCOLOR tdiff; /* diffuse transmission */
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double rspec; /* specular reflectance (1 for BRDTF) */
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double trans; /* transmissivity (.5 for BRDTF) */
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double tspec; /* specular transmittance (1 for BRDTF) */
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FVECT pnorm; /* perturbed surface normal */
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double pdot; /* perturbed dot product */
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} BRDFDAT; /* BRDF material data */
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static int setbrdfunc(BRDFDAT *np);
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static void
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dirbrdf( /* compute source contribution */
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SCOLOR scval, /* returned coefficient */
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void *nnp, /* material data */
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FVECT ldir, /* light source direction */
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double omega /* light source size */
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)
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{
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BRDFDAT *np = nnp;
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double ldot;
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double dtmp;
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SCOLOR sctmp;
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COLOR ctmp;
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FVECT ldx;
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static double vldx[5], pt[MAXDDIM];
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char **sa;
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int i;
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#define lddx (vldx+1)
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scolorblack(scval);
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ldot = DOT(np->pnorm, ldir);
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if (ldot <= FTINY && ldot >= -FTINY)
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return; /* too close to grazing */
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if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
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return; /* wrong side */
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if (ldot > 0.0) {
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/*
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* Compute and add diffuse reflected component to returned
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* color. The diffuse reflected component will always be
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* modified by the color of the material.
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*/
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copyscolor(sctmp, np->rdiff);
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dtmp = ldot * omega / PI;
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scalescolor(sctmp, dtmp);
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saddscolor(scval, sctmp);
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} else {
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/*
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* Diffuse transmitted component.
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*/
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copyscolor(sctmp, np->tdiff);
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dtmp = -ldot * omega / PI;
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scalescolor(sctmp, dtmp);
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saddscolor(scval, sctmp);
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}
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if ((ldot > 0.0 ? np->rspec <= FTINY : np->tspec <= FTINY) ||
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ambRayInPmap(np->pr))
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return; /* diffuse only */
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/* set up function */
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setbrdfunc(np);
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sa = np->mp->oargs.sarg;
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errno = 0;
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/* transform light vector */
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multv3(ldx, ldir, funcxf.xfm);
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for (i = 0; i < 3; i++)
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lddx[i] = ldx[i]/funcxf.sca;
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lddx[3] = omega;
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/* compute BRTDF */
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if (np->mp->otype == MAT_BRTDF) {
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if (sa[6][0] == '0' && !sa[6][1]) /* special case */
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colval(ctmp,RED) = 0.0;
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else
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colval(ctmp,RED) = funvalue(sa[6], 4, lddx);
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if (sa[7][0] == '0' && !sa[7][1])
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colval(ctmp,GRN) = 0.0;
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else if (!strcmp(sa[7],sa[6]))
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colval(ctmp,GRN) = colval(ctmp,RED);
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else
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colval(ctmp,GRN) = funvalue(sa[7], 4, lddx);
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if (sa[8][0] == '0' && !sa[8][1])
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colval(ctmp,BLU) = 0.0;
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else if (!strcmp(sa[8],sa[6]))
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colval(ctmp,BLU) = colval(ctmp,RED);
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else if (!strcmp(sa[8],sa[7]))
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colval(ctmp,BLU) = colval(ctmp,GRN);
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else
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colval(ctmp,BLU) = funvalue(sa[8], 4, lddx);
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dtmp = bright(ctmp);
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} else if (np->dp == NULL) {
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dtmp = funvalue(sa[0], 4, lddx);
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setcolor(ctmp, dtmp, dtmp, dtmp);
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} else {
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for (i = 0; i < np->dp->nd; i++)
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pt[i] = funvalue(sa[3+i], 4, lddx);
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vldx[0] = datavalue(np->dp, pt);
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dtmp = funvalue(sa[0], 5, vldx);
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setcolor(ctmp, dtmp, dtmp, dtmp);
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}
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if ((errno == EDOM) | (errno == ERANGE)) {
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objerror(np->mp, WARNING, "compute error");
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return;
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}
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if (dtmp <= FTINY)
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return;
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setscolor(sctmp, colval(ctmp,RED), colval(ctmp,GRN), colval(ctmp,BLU));
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if (ldot > 0.0) {
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/*
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* Compute reflected non-diffuse component.
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*/
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if ((np->mp->otype == MAT_MFUNC) | (np->mp->otype == MAT_MDATA))
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smultscolor(sctmp, np->mcolor);
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dtmp = ldot * omega * np->rspec;
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scalescolor(sctmp, dtmp);
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saddscolor(scval, sctmp);
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} else {
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/*
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* Compute transmitted non-diffuse component.
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*/
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if ((np->mp->otype == MAT_TFUNC) | (np->mp->otype == MAT_TDATA))
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smultscolor(sctmp, np->mcolor);
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dtmp = -ldot * omega * np->tspec;
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scalescolor(sctmp, dtmp);
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saddscolor(scval, sctmp);
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}
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#undef lddx
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}
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int
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m_brdf( /* color a ray that hit a BRDTfunc material */
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OBJREC *m,
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RAY *r
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)
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{
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BRDFDAT nd;
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RAY sr;
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int hasrefl, hastrans;
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int hastexture;
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SCOLOR sctmp;
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FVECT vtmp;
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double d;
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MFUNC *mf;
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int i;
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/* check arguments */
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if ((m->oargs.nsargs < 10) | (m->oargs.nfargs < 9))
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objerror(m, USER, "bad # arguments");
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nd.mp = m;
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nd.pr = r;
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/* dummy values */
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nd.rspec = nd.tspec = 1.0;
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nd.trans = 0.5;
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/* diffuse reflectance */
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if (r->rod > 0.0)
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setscolor(nd.rdiff, m->oargs.farg[0],
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m->oargs.farg[1],
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m->oargs.farg[2]);
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else
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setscolor(nd.rdiff, m->oargs.farg[3],
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m->oargs.farg[4],
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m->oargs.farg[5]);
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/* diffuse transmittance */
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setscolor(nd.tdiff, m->oargs.farg[6],
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m->oargs.farg[7],
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m->oargs.farg[8]);
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/* get modifiers */
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raytexture(r, m->omod);
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hastexture = (DOT(r->pert,r->pert) > FTINY*FTINY);
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if (hastexture) { /* perturb normal */
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nd.pdot = raynormal(nd.pnorm, r);
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} else {
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VCOPY(nd.pnorm, r->ron);
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nd.pdot = r->rod;
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}
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if (r->rod < 0.0) { /* orient perturbed values */
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nd.pdot = -nd.pdot;
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for (i = 0; i < 3; i++) {
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nd.pnorm[i] = -nd.pnorm[i];
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r->pert[i] = -r->pert[i];
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}
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}
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copyscolor(nd.mcolor, r->pcol); /* get pattern color */
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smultscolor(nd.rdiff, nd.mcolor); /* modify diffuse values */
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smultscolor(nd.tdiff, nd.mcolor);
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hasrefl = (sintens(nd.rdiff) > FTINY);
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hastrans = (sintens(nd.tdiff) > FTINY);
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/* load cal file */
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nd.dp = NULL;
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mf = getfunc(m, 9, 0x3F, 0);
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/* compute transmitted ray */
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setbrdfunc(&nd);
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errno = 0;
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setscolor(sctmp, evalue(mf->ep[3]),
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evalue(mf->ep[4]),
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evalue(mf->ep[5]));
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if ((errno == EDOM) | (errno == ERANGE))
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objerror(m, WARNING, "compute error");
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else if (rayorigin(&sr, TRANS, r, sctmp) == 0) {
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if (hastexture && !(r->crtype & (SHADOW|AMBIENT))) {
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/* perturb direction */
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VSUB(sr.rdir, r->rdir, r->pert);
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if (normalize(sr.rdir) == 0.0) {
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objerror(m, WARNING, "illegal perturbation");
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VCOPY(sr.rdir, r->rdir);
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}
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} else {
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VCOPY(sr.rdir, r->rdir);
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}
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rayvalue(&sr);
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smultscolor(sr.rcol, sr.rcoef);
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saddscolor(r->rcol, sr.rcol);
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if ((!hastexture || r->crtype & (SHADOW|AMBIENT)) &&
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nd.tspec > pbright(nd.tdiff) + pbright(nd.rdiff))
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r->rxt = r->rot + raydistance(&sr);
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}
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if (r->crtype & SHADOW) /* the rest is shadow */
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return(1);
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/* compute reflected ray */
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setbrdfunc(&nd);
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errno = 0;
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setscolor(sctmp, 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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| 301 |
objerror(m, WARNING, "compute error");
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else if (rayorigin(&sr, REFLECTED, r, sctmp) == 0) {
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VSUM(sr.rdir, r->rdir, nd.pnorm, 2.*nd.pdot);
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| 304 |
checknorm(sr.rdir);
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rayvalue(&sr);
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| 306 |
smultscolor(sr.rcol, sr.rcoef);
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copyscolor(r->mcol, sr.rcol);
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| 308 |
saddscolor(r->rcol, sr.rcol);
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| 309 |
r->rmt = r->rot;
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| 310 |
if (r->ro != NULL && isflat(r->ro->otype) &&
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| 311 |
!hastexture | (r->crtype & AMBIENT))
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| 312 |
r->rmt += raydistance(&sr);
|
| 313 |
}
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| 314 |
/* compute ambient */
|
| 315 |
if (hasrefl) {
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| 316 |
copyscolor(sctmp, nd.rdiff);
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| 317 |
multambient(sctmp, r, nd.pnorm);
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| 318 |
saddscolor(r->rcol, sctmp); /* add to returned color */
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| 319 |
}
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| 320 |
if (hastrans) { /* from other side */
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| 321 |
vtmp[0] = -nd.pnorm[0];
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| 322 |
vtmp[1] = -nd.pnorm[1];
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| 323 |
vtmp[2] = -nd.pnorm[2];
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| 324 |
copyscolor(sctmp, nd.tdiff);
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| 325 |
multambient(sctmp, r, vtmp);
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| 326 |
saddscolor(r->rcol, sctmp);
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| 327 |
}
|
| 328 |
if (hasrefl | hastrans || m->oargs.sarg[6][0] != '0')
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| 329 |
direct(r, dirbrdf, &nd); /* add direct component */
|
| 330 |
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| 331 |
return(1);
|
| 332 |
}
|
| 333 |
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| 334 |
|
| 335 |
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| 336 |
int
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| 337 |
m_brdf2( /* color a ray that hit a BRDF material */
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| 338 |
OBJREC *m,
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| 339 |
RAY *r
|
| 340 |
)
|
| 341 |
{
|
| 342 |
BRDFDAT nd;
|
| 343 |
SCOLOR sctmp;
|
| 344 |
FVECT vtmp;
|
| 345 |
double dtmp;
|
| 346 |
/* always a shadow */
|
| 347 |
if (r->crtype & SHADOW)
|
| 348 |
return(1);
|
| 349 |
/* check for back side */
|
| 350 |
if (r->rod < 0.0) {
|
| 351 |
if (!backvis) {
|
| 352 |
raytrans(r);
|
| 353 |
return(1);
|
| 354 |
}
|
| 355 |
raytexture(r, m->omod);
|
| 356 |
flipsurface(r); /* reorient if backvis */
|
| 357 |
} else
|
| 358 |
raytexture(r, m->omod);
|
| 359 |
/* check arguments */
|
| 360 |
if ((m->oargs.nsargs < (hasdata(m->otype)?4:2)) | (m->oargs.nfargs <
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| 361 |
((m->otype==MAT_TFUNC)|(m->otype==MAT_TDATA)?6:4)))
|
| 362 |
objerror(m, USER, "bad # arguments");
|
| 363 |
|
| 364 |
nd.mp = m;
|
| 365 |
nd.pr = r;
|
| 366 |
/* get material color */
|
| 367 |
setscolor(nd.mcolor, m->oargs.farg[0],
|
| 368 |
m->oargs.farg[1],
|
| 369 |
m->oargs.farg[2]);
|
| 370 |
/* get specular component */
|
| 371 |
nd.rspec = m->oargs.farg[3];
|
| 372 |
/* compute transmittance */
|
| 373 |
if ((m->otype == MAT_TFUNC) | (m->otype == MAT_TDATA)) {
|
| 374 |
nd.trans = m->oargs.farg[4]*(1.0 - nd.rspec);
|
| 375 |
nd.tspec = nd.trans * m->oargs.farg[5];
|
| 376 |
dtmp = nd.trans - nd.tspec;
|
| 377 |
setscolor(nd.tdiff, dtmp, dtmp, dtmp);
|
| 378 |
} else {
|
| 379 |
nd.tspec = nd.trans = 0.0;
|
| 380 |
scolorblack(nd.tdiff);
|
| 381 |
}
|
| 382 |
/* compute reflectance */
|
| 383 |
dtmp = 1.0 - nd.trans - nd.rspec;
|
| 384 |
setscolor(nd.rdiff, dtmp, dtmp, dtmp);
|
| 385 |
nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
|
| 386 |
smultscolor(nd.mcolor, r->pcol); /* modify material color */
|
| 387 |
smultscolor(nd.rdiff, nd.mcolor);
|
| 388 |
smultscolor(nd.tdiff, nd.mcolor);
|
| 389 |
/* load auxiliary files */
|
| 390 |
if (hasdata(m->otype)) {
|
| 391 |
nd.dp = getdata(m->oargs.sarg[1]);
|
| 392 |
getfunc(m, 2, 0, 0);
|
| 393 |
} else {
|
| 394 |
nd.dp = NULL;
|
| 395 |
getfunc(m, 1, 0, 0);
|
| 396 |
}
|
| 397 |
/* compute ambient */
|
| 398 |
if (nd.trans < 1.0-FTINY) {
|
| 399 |
copyscolor(sctmp, nd.mcolor); /* modified by material color */
|
| 400 |
scalescolor(sctmp, 1.0-nd.trans);
|
| 401 |
multambient(sctmp, r, nd.pnorm);
|
| 402 |
saddscolor(r->rcol, sctmp); /* add to returned color */
|
| 403 |
}
|
| 404 |
if (nd.trans > FTINY) { /* from other side */
|
| 405 |
vtmp[0] = -nd.pnorm[0];
|
| 406 |
vtmp[1] = -nd.pnorm[1];
|
| 407 |
vtmp[2] = -nd.pnorm[2];
|
| 408 |
copyscolor(sctmp, nd.mcolor);
|
| 409 |
scalescolor(sctmp, nd.trans);
|
| 410 |
multambient(sctmp, r, vtmp);
|
| 411 |
saddscolor(r->rcol, sctmp);
|
| 412 |
}
|
| 413 |
/* add direct component */
|
| 414 |
direct(r, dirbrdf, &nd);
|
| 415 |
|
| 416 |
return(1);
|
| 417 |
}
|
| 418 |
|
| 419 |
|
| 420 |
static int
|
| 421 |
setbrdfunc( /* set up brdf function and variables */
|
| 422 |
BRDFDAT *np
|
| 423 |
)
|
| 424 |
{
|
| 425 |
FVECT vec;
|
| 426 |
COLOR ctmp;
|
| 427 |
|
| 428 |
if (setfunc(np->mp, np->pr) == 0)
|
| 429 |
return(0); /* it's OK, setfunc says we're done */
|
| 430 |
/* else (re)assign special variables */
|
| 431 |
multv3(vec, np->pnorm, funcxf.xfm);
|
| 432 |
varset("NxP`", '=', vec[0]/funcxf.sca);
|
| 433 |
varset("NyP`", '=', vec[1]/funcxf.sca);
|
| 434 |
varset("NzP`", '=', vec[2]/funcxf.sca);
|
| 435 |
varset("RdotP`", '=', np->pdot);
|
| 436 |
scolor_color(ctmp, np->mcolor); /* should use scolor_rgb()? */
|
| 437 |
varset("CrP", '=', colval(ctmp,RED));
|
| 438 |
varset("CgP", '=', colval(ctmp,GRN));
|
| 439 |
varset("CbP", '=', colval(ctmp,BLU));
|
| 440 |
return(1);
|
| 441 |
}
|
