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#ifndef lint |
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static const char RCSid[] = "$Id: m_brdf.c,v 2.40 2023/11/15 18:02:52 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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int hitfront = 1; |
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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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hitfront = 0; |
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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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|
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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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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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checknorm(sr.rdir); |
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rayvalue(&sr); |
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smultscolor(sr.rcol, sr.rcoef); |
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copyscolor(r->mcol, sr.rcol); |
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saddscolor(r->rcol, sr.rcol); |
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r->rmt = r->rot; |
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if (r->ro != NULL && isflat(r->ro->otype) && |
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!hastexture | (r->crtype & AMBIENT)) |
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r->rmt += raydistance(&sr); |
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} |
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/* compute ambient */ |
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if (hasrefl) { |
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copyscolor(sctmp, nd.rdiff); |
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multambient(sctmp, r, nd.pnorm); |
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saddscolor(r->rcol, sctmp); /* add to returned color */ |
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} |
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if (hastrans) { /* from other side */ |
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vtmp[0] = -nd.pnorm[0]; |
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vtmp[1] = -nd.pnorm[1]; |
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vtmp[2] = -nd.pnorm[2]; |
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copyscolor(sctmp, nd.tdiff); |
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multambient(sctmp, r, vtmp); |
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saddscolor(r->rcol, sctmp); |
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} |
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if (hasrefl | hastrans || m->oargs.sarg[6][0] != '0') |
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direct(r, dirbrdf, &nd); /* add direct component */ |
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|
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return(1); |
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} |
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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 */ |
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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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SCOLOR sctmp; |
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FVECT vtmp; |
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double dtmp; |
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/* always a shadow */ |
349 |
if (r->crtype & SHADOW) |
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return(1); |
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/* check arguments */ |
352 |
if ((m->oargs.nsargs < (hasdata(m->otype)?4:2)) | (m->oargs.nfargs < |
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((m->otype==MAT_TFUNC)|(m->otype==MAT_TDATA)?6:4))) |
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objerror(m, USER, "bad # arguments"); |
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/* check for back side */ |
356 |
if (r->rod < 0.0) { |
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if (!backvis) { |
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raytrans(r); |
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return(1); |
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} |
361 |
raytexture(r, m->omod); |
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flipsurface(r); /* reorient if backvis */ |
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} else |
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raytexture(r, m->omod); |
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|
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nd.mp = m; |
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nd.pr = r; |
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/* get material color */ |
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setscolor(nd.mcolor, m->oargs.farg[0], |
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m->oargs.farg[1], |
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m->oargs.farg[2]); |
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/* get specular component */ |
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nd.rspec = m->oargs.farg[3]; |
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/* compute transmittance */ |
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if ((m->otype == MAT_TFUNC) | (m->otype == MAT_TDATA)) { |
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nd.trans = m->oargs.farg[4]*(1.0 - nd.rspec); |
377 |
nd.tspec = nd.trans * m->oargs.farg[5]; |
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dtmp = nd.trans - nd.tspec; |
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setscolor(nd.tdiff, dtmp, dtmp, dtmp); |
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} else { |
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nd.tspec = nd.trans = 0.0; |
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scolorblack(nd.tdiff); |
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} |
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/* compute reflectance */ |
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dtmp = 1.0 - nd.trans - nd.rspec; |
386 |
setscolor(nd.rdiff, dtmp, dtmp, dtmp); |
387 |
nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */ |
388 |
smultscolor(nd.mcolor, r->pcol); /* modify material color */ |
389 |
smultscolor(nd.rdiff, nd.mcolor); |
390 |
smultscolor(nd.tdiff, nd.mcolor); |
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/* load auxiliary files */ |
392 |
if (hasdata(m->otype)) { |
393 |
nd.dp = getdata(m->oargs.sarg[1]); |
394 |
getfunc(m, 2, 0, 0); |
395 |
} else { |
396 |
nd.dp = NULL; |
397 |
getfunc(m, 1, 0, 0); |
398 |
} |
399 |
/* compute ambient */ |
400 |
if (nd.trans < 1.0-FTINY) { |
401 |
copyscolor(sctmp, nd.mcolor); /* modified by material color */ |
402 |
scalescolor(sctmp, 1.0-nd.trans); |
403 |
multambient(sctmp, r, nd.pnorm); |
404 |
saddscolor(r->rcol, sctmp); /* add to returned color */ |
405 |
} |
406 |
if (nd.trans > FTINY) { /* from other side */ |
407 |
vtmp[0] = -nd.pnorm[0]; |
408 |
vtmp[1] = -nd.pnorm[1]; |
409 |
vtmp[2] = -nd.pnorm[2]; |
410 |
copyscolor(sctmp, nd.mcolor); |
411 |
scalescolor(sctmp, nd.trans); |
412 |
multambient(sctmp, r, vtmp); |
413 |
saddscolor(r->rcol, sctmp); |
414 |
} |
415 |
/* add direct component */ |
416 |
direct(r, dirbrdf, &nd); |
417 |
|
418 |
return(1); |
419 |
} |
420 |
|
421 |
|
422 |
static int |
423 |
setbrdfunc( /* set up brdf function and variables */ |
424 |
BRDFDAT *np |
425 |
) |
426 |
{ |
427 |
FVECT vec; |
428 |
COLOR ctmp; |
429 |
|
430 |
if (setfunc(np->mp, np->pr) == 0) |
431 |
return(0); /* it's OK, setfunc says we're done */ |
432 |
/* else (re)assign special variables */ |
433 |
multv3(vec, np->pnorm, funcxf.xfm); |
434 |
varset("NxP`", '=', vec[0]/funcxf.sca); |
435 |
varset("NyP`", '=', vec[1]/funcxf.sca); |
436 |
varset("NzP`", '=', vec[2]/funcxf.sca); |
437 |
varset("RdotP`", '=', np->pdot <= -1.0 ? -1.0 : |
438 |
np->pdot >= 1.0 ? 1.0 : np->pdot); |
439 |
scolor_color(ctmp, np->mcolor); /* should use scolor_rgb()? */ |
440 |
varset("CrP", '=', colval(ctmp,RED)); |
441 |
varset("CgP", '=', colval(ctmp,GRN)); |
442 |
varset("CbP", '=', colval(ctmp,BLU)); |
443 |
return(1); |
444 |
} |