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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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|
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#include "copyright.h" |
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|
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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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/* |
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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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|
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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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|
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|
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static int setbrdfunc(BRDFDAT *np); |
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|
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|
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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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|
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scolorblack(scval); |
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|
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ldot = DOT(np->pnorm, ldir); |
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|
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if (ldot <= FTINY && ldot >= -FTINY) |
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return; /* too close to grazing */ |
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|
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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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|
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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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|
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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); |
| 277 |
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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} |
| 281 |
} 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); |
| 287 |
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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} |
| 291 |
if (r->crtype & SHADOW) /* the rest is shadow */ |
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return(1); |
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|
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/* compute reflected ray */ |
| 295 |
setbrdfunc(&nd); |
| 296 |
errno = 0; |
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setscolor(sctmp, evalue(mf->ep[0]), |
| 298 |
evalue(mf->ep[1]), |
| 299 |
evalue(mf->ep[2])); |
| 300 |
if ((errno == EDOM) | (errno == ERANGE)) |
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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); |
| 304 |
checknorm(sr.rdir); |
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rayvalue(&sr); |
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smultscolor(sr.rcol, sr.rcoef); |
| 307 |
copyscolor(r->mcol, sr.rcol); |
| 308 |
saddscolor(r->rcol, sr.rcol); |
| 309 |
r->rmt = r->rot; |
| 310 |
if (r->ro != NULL && isflat(r->ro->otype) && |
| 311 |
!hastexture | (r->crtype & AMBIENT)) |
| 312 |
r->rmt += raydistance(&sr); |
| 313 |
} |
| 314 |
/* compute ambient */ |
| 315 |
if (hasrefl) { |
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copyscolor(sctmp, nd.rdiff); |
| 317 |
multambient(sctmp, r, nd.pnorm); |
| 318 |
saddscolor(r->rcol, sctmp); /* add to returned color */ |
| 319 |
} |
| 320 |
if (hastrans) { /* from other side */ |
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vtmp[0] = -nd.pnorm[0]; |
| 322 |
vtmp[1] = -nd.pnorm[1]; |
| 323 |
vtmp[2] = -nd.pnorm[2]; |
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copyscolor(sctmp, nd.tdiff); |
| 325 |
multambient(sctmp, r, vtmp); |
| 326 |
saddscolor(r->rcol, sctmp); |
| 327 |
} |
| 328 |
if (hasrefl | hastrans || m->oargs.sarg[6][0] != '0') |
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direct(r, dirbrdf, &nd); /* add direct component */ |
| 330 |
|
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return(1); |
| 332 |
} |
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|
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|
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|
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int |
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m_brdf2( /* color a ray that hit a BRDF material */ |
| 338 |
OBJREC *m, |
| 339 |
RAY *r |
| 340 |
) |
| 341 |
{ |
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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 < |
| 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 |
} |
