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/* Copyright (c) 1986 Regents of the University of California */ |
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|
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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|
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/* |
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* normal.c - shading function for normal materials. |
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* |
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* 8/19/85 |
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* 12/19/85 - added stuff for metals. |
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* 6/26/87 - improved specular model. |
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* 9/28/87 - added model for translucent materials. |
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*/ |
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|
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#include "ray.h" |
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|
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#include "source.h" |
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|
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#include "otypes.h" |
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|
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/* |
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* This routine uses portions of the reflection |
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* model described by Cook and Torrance. |
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* The computation of specular components has been simplified by |
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* numerous approximations and ommisions to improve speed. |
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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_PLASTIC and MAT_METAL are: |
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* red grn blu specular-frac. facet-slope |
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* |
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* Arguments for MAT_TRANS are: |
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* red grn blu rspec rough trans tspec |
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*/ |
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|
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#define BSPEC(m) (6.0) /* specularity parameter b */ |
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|
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|
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m_normal(m, r) /* color a ray which hit something normal */ |
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register OBJREC *m; |
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register RAY *r; |
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{ |
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double exp(); |
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COLOR mcolor; /* color of this material */ |
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COLOR scolor; /* color of specular component */ |
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FVECT vrefl; /* vector in direction of reflected ray */ |
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double alpha2; /* roughness squared times 2 */ |
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RAY lr; /* ray to illumination source */ |
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double rdiff, rspec; /* reflected specular, diffuse */ |
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double trans; /* transmissivity */ |
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double tdiff, tspec; /* transmitted specular, diffuse */ |
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FVECT pnorm; /* perturbed surface normal */ |
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double pdot; /* perturbed dot product */ |
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double ldot; |
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double omega; |
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double dtmp; |
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COLOR ctmp; |
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register int i; |
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|
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if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5)) |
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objerror(m, USER, "bad # arguments"); |
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/* easy shadow test */ |
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if (r->crtype & SHADOW && m->otype != MAT_TRANS) |
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return; |
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/* get material color */ |
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setcolor(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 roughness */ |
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alpha2 = m->oargs.farg[4]; |
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alpha2 *= 2.0 * alpha2; |
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/* reorient if necessary */ |
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if (r->rod < 0.0) |
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flipsurface(r); |
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/* get modifiers */ |
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raytexture(r, m->omod); |
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pdot = raynormal(pnorm, r); /* perturb normal */ |
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multcolor(mcolor, r->pcol); /* modify material color */ |
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/* get specular component */ |
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rspec = m->oargs.farg[3]; |
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|
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if (rspec > FTINY) { /* has specular component */ |
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/* compute specular color */ |
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if (m->otype == MAT_METAL) |
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copycolor(scolor, mcolor); |
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else |
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setcolor(scolor, 1.0, 1.0, 1.0); |
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scalecolor(scolor, rspec); |
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/* improved model */ |
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dtmp = exp(-BSPEC(m)*pdot); |
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for (i = 0; i < 3; i++) |
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colval(scolor,i) += (1.0-colval(scolor,i))*dtmp; |
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rspec += (1.0-rspec)*dtmp; |
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/* compute reflected ray */ |
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for (i = 0; i < 3; i++) |
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vrefl[i] = r->rdir[i] + 2.0*pdot*pnorm[i]; |
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|
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if (alpha2 <= FTINY && !(r->crtype & SHADOW)) |
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if (rayorigin(&lr, r, REFLECTED, rspec) == 0) { |
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VCOPY(lr.rdir, vrefl); |
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rayvalue(&lr); |
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multcolor(lr.rcol, scolor); |
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addcolor(r->rcol, lr.rcol); |
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} |
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} |
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|
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if (m->otype == MAT_TRANS) { |
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trans = m->oargs.farg[5]*(1.0 - rspec); |
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tspec = trans * m->oargs.farg[6]; |
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tdiff = trans - tspec; |
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} else |
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tdiff = tspec = trans = 0.0; |
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/* transmitted ray */ |
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if (tspec > FTINY && alpha2 <= FTINY) |
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if (rayorigin(&lr, r, TRANS, tspec) == 0) { |
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VCOPY(lr.rdir, r->rdir); |
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rayvalue(&lr); |
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scalecolor(lr.rcol, tspec); |
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addcolor(r->rcol, lr.rcol); |
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} |
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if (r->crtype & SHADOW) /* the rest is shadow */ |
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return; |
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/* diffuse reflection */ |
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rdiff = 1.0 - trans - rspec; |
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|
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if (rdiff <= FTINY && tdiff <= FTINY && alpha2 <= FTINY) |
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return; /* purely specular */ |
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|
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if (rdiff > FTINY) { /* ambient from this side */ |
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ambient(ctmp, r); |
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if (alpha2 <= FTINY) |
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scalecolor(ctmp, rdiff); |
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else |
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scalecolor(ctmp, 1.0-trans); |
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multcolor(ctmp, mcolor); /* modified by material color */ |
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addcolor(r->rcol, ctmp); /* add to returned color */ |
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} |
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if (tdiff > FTINY) { /* ambient from other side */ |
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flipsurface(r); |
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ambient(ctmp, r); |
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if (alpha2 <= FTINY) |
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scalecolor(ctmp, tdiff); |
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else |
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scalecolor(ctmp, trans); |
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multcolor(ctmp, mcolor); |
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addcolor(r->rcol, ctmp); |
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flipsurface(r); |
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} |
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|
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for (i = 0; i < nsources; i++) { /* add specular and diffuse */ |
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|
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if ((omega = srcray(&lr, r, i)) == 0.0) |
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continue; /* bad source */ |
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|
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ldot = DOT(pnorm, lr.rdir); |
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|
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if (ldot < 0.0 ? trans <= FTINY : trans >= 1.0-FTINY) |
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continue; /* wrong side */ |
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|
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rayvalue(&lr); /* compute light ray value */ |
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|
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if (intens(lr.rcol) <= FTINY) |
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continue; /* didn't hit light source */ |
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|
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if (ldot > FTINY && rdiff > FTINY) { |
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/* |
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* Compute and add diffuse component to returned color. |
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* The diffuse component will always be modified by the |
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* color of the material. |
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*/ |
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copycolor(ctmp, lr.rcol); |
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dtmp = ldot * omega * rdiff / PI; |
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scalecolor(ctmp, dtmp); |
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multcolor(ctmp, mcolor); |
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addcolor(r->rcol, ctmp); |
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} |
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if (ldot > FTINY && rspec > FTINY && alpha2 > FTINY) { |
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/* |
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* Compute specular reflection coefficient using |
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* gaussian distribution model. |
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*/ |
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/* roughness + source */ |
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dtmp = alpha2 + omega/(2.0*PI); |
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/* gaussian */ |
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dtmp = exp((DOT(vrefl,lr.rdir)-1.)/dtmp)/(2.*PI)/dtmp; |
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/* worth using? */ |
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if (dtmp > FTINY) { |
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copycolor(ctmp, lr.rcol); |
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dtmp *= omega; |
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scalecolor(ctmp, dtmp); |
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multcolor(ctmp, scolor); |
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addcolor(r->rcol, ctmp); |
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} |
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} |
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if (ldot < -FTINY && tdiff > FTINY) { |
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/* |
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* Compute diffuse transmission. |
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*/ |
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copycolor(ctmp, lr.rcol); |
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dtmp = -ldot * omega * tdiff / PI; |
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scalecolor(ctmp, dtmp); |
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multcolor(ctmp, mcolor); |
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addcolor(r->rcol, ctmp); |
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} |
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if (ldot < -FTINY && tspec > FTINY && alpha2 > FTINY) { |
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/* |
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* Compute specular transmission. |
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*/ |
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/* roughness + source */ |
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dtmp = alpha2 + omega/(2.0*PI); |
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/* gaussian */ |
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dtmp = exp((DOT(r->rdir,lr.rdir)-1.)/dtmp)/(2.*PI)/dtmp; |
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/* worth using? */ |
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if (dtmp > FTINY) { |
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copycolor(ctmp, lr.rcol); |
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dtmp *= tspec * omega; |
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scalecolor(ctmp, dtmp); |
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addcolor(r->rcol, ctmp); |
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} |
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} |
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} |
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} |
