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#ifndef lint |
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static const char RCSid[] = "$Id: m_clip.c,v 2.12 2017/04/08 00:09:35 greg Exp $"; |
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#endif |
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/* |
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* m_clip.c - routine for clipped (cut) objects. |
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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 "rtotypes.h" |
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|
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/* |
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* Clipping objects permit holes and sections to be taken out |
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* of other objects. |
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* |
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* The argument is the clipped materials; |
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* the first is used to shade upon exit. |
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* |
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* In the simple case of the first argument being "void", we |
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* just add or subtract (depending on whether we're coming or going) |
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* the list of modifiers to the ray's "newcset", which will then |
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* take over for "clipset" on penetration. Any surface modifier |
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* names found in "clipset" will be treated as invisible in raycont(). |
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* |
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* In the more complicated case of a non-void material as the |
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* first argument, we have to backtrack up the ray tree to count |
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* the number of times we've penetrated the front side of one of |
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* the surfaces we care about. This relies on outward-facing |
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* surface normals and closed objects, so is somewhat error-prone. |
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*/ |
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|
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|
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int |
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m_clip( /* clip objects from ray */ |
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OBJREC *m, |
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RAY *r |
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) |
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{ |
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OBJECT cset[MAXSET+1], *modset; |
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OBJECT obj, mod; |
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int entering; |
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int i; |
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|
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obj = objndx(m); |
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if ((modset = (OBJECT *)m->os) == NULL) { |
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if (m->oargs.nsargs < 1 || m->oargs.nsargs > MAXSET) |
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objerror(m, USER, "bad # arguments"); |
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modset = (OBJECT *)malloc((m->oargs.nsargs+1)*sizeof(OBJECT)); |
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if (modset == NULL) |
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error(SYSTEM, "out of memory in m_clip"); |
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modset[0] = 0; |
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for (i = 0; i < m->oargs.nsargs; i++) { |
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if (!strcmp(m->oargs.sarg[i], VOIDID)) |
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continue; |
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if ((mod = lastmod(obj, m->oargs.sarg[i])) == OVOID) { |
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sprintf(errmsg, "unknown modifier \"%s\"", |
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m->oargs.sarg[i]); |
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objerror(m, WARNING, errmsg); |
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continue; |
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} |
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if (inset(modset, mod)) { |
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objerror(m, WARNING, "duplicate modifier"); |
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continue; |
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} |
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insertelem(modset, mod); |
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} |
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m->os = (char *)modset; |
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} |
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if (r == NULL) |
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return(0); /* just initializing */ |
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if (r->clipset != NULL) |
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setcopy(cset, r->clipset); |
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else |
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cset[0] = 0; |
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|
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entering = (r->rod > 0.0); /* entering clipped region? */ |
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|
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for (i = modset[0]; i > 0; i--) |
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if (entering) { |
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if (!inset(cset, modset[i])) { |
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if (cset[0] >= MAXSET) |
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error(INTERNAL, "set overflow in m_clip"); |
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insertelem(cset, modset[i]); |
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} |
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} else if (inset(cset, modset[i])) |
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deletelem(cset, modset[i]); |
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|
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/* compute ray value */ |
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r->newcset = cset; |
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if (strcmp(m->oargs.sarg[0], VOIDID)) { |
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int inside = 0; |
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const RAY *rp; |
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/* check for penetration */ |
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for (rp = r; rp->parent != NULL; rp = rp->parent) |
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if ((rp->rtype == RAYREFL) & (rp->parent->ro != NULL) |
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&& inset(modset, rp->parent->ro->omod)) { |
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if (rp->parent->rod > 0.0) |
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inside++; |
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else |
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inside--; |
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} |
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if (inside > 0) { /* we just hit the object */ |
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flipsurface(r); |
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return(rayshade(r, lastmod(obj, m->oargs.sarg[0]))); |
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} |
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} |
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raytrans(r); /* else transfer ray */ |
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return(1); |
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} |
