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#ifndef lint
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static const char RCSid[] = "$Id: m_clip.c,v 2.7 2003/07/21 22:30:19 schorsch 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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#include "copyright.h"
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#include "ray.h"
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#include "rtotypes.h"
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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. The method is simple:
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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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extern int
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m_clip( /* clip objects from ray */
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register OBJREC *m,
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register 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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register int i;
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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->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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entering = r->rod > 0.0; /* entering clipped region? */
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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 {
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if (inset(cset, modset[i]))
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deletelem(cset, modset[i]);
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}
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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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register 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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}
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