| 1 |
#ifndef lint |
| 2 |
static const char RCSid[] = "$Id: m_clip.c,v 2.13 2019/05/04 03:14:04 greg Exp $"; |
| 3 |
#endif |
| 4 |
/* |
| 5 |
* m_clip.c - routine for clipped (cut) objects. |
| 6 |
*/ |
| 7 |
|
| 8 |
#include "copyright.h" |
| 9 |
|
| 10 |
#include "ray.h" |
| 11 |
#include "rtotypes.h" |
| 12 |
|
| 13 |
/* |
| 14 |
* Clipping objects permit holes and sections to be taken out |
| 15 |
* of other objects. |
| 16 |
* |
| 17 |
* The argument is the clipped materials; |
| 18 |
* the first is used to shade upon exit. |
| 19 |
* |
| 20 |
* In the simple case of the first argument being "void", we |
| 21 |
* just add or subtract (depending on whether we're coming or going) |
| 22 |
* the list of modifiers to the ray's "newcset", which will then |
| 23 |
* take over for "clipset" on penetration. Any surface modifier |
| 24 |
* names found in "clipset" will be treated as invisible in raycont(). |
| 25 |
* |
| 26 |
* In the more complicated case of a non-void material as the |
| 27 |
* first argument, we have to backtrack up the ray tree to count |
| 28 |
* the number of times we've penetrated the front side of one of |
| 29 |
* the surfaces we care about. This relies on outward-facing |
| 30 |
* surface normals and closed objects, so is somewhat error-prone. |
| 31 |
*/ |
| 32 |
|
| 33 |
|
| 34 |
int |
| 35 |
m_clip( /* clip objects from ray */ |
| 36 |
OBJREC *m, |
| 37 |
RAY *r |
| 38 |
) |
| 39 |
{ |
| 40 |
OBJECT cset[MAXSET+1], *modset; |
| 41 |
OBJECT obj, mod; |
| 42 |
int entering; |
| 43 |
int i; |
| 44 |
|
| 45 |
obj = objndx(m); |
| 46 |
if ((modset = (OBJECT *)m->os) == NULL) { |
| 47 |
if (m->oargs.nsargs < 1 || m->oargs.nsargs > MAXSET) |
| 48 |
objerror(m, USER, "bad # arguments"); |
| 49 |
modset = (OBJECT *)malloc((m->oargs.nsargs+1)*sizeof(OBJECT)); |
| 50 |
if (modset == NULL) |
| 51 |
error(SYSTEM, "out of memory in m_clip"); |
| 52 |
modset[0] = 0; |
| 53 |
for (i = 0; i < m->oargs.nsargs; i++) { |
| 54 |
if (!strcmp(m->oargs.sarg[i], VOIDID)) |
| 55 |
continue; |
| 56 |
if ((mod = lastmod(obj, m->oargs.sarg[i])) == OVOID) { |
| 57 |
sprintf(errmsg, "unknown modifier \"%s\"", |
| 58 |
m->oargs.sarg[i]); |
| 59 |
objerror(m, WARNING, errmsg); |
| 60 |
continue; |
| 61 |
} |
| 62 |
if (inset(modset, mod)) { |
| 63 |
objerror(m, WARNING, "duplicate modifier"); |
| 64 |
continue; |
| 65 |
} |
| 66 |
insertelem(modset, mod); |
| 67 |
} |
| 68 |
m->os = (char *)modset; |
| 69 |
} |
| 70 |
if (r == NULL) |
| 71 |
return(0); /* just initializing */ |
| 72 |
if (r->clipset != NULL) |
| 73 |
setcopy(cset, r->clipset); |
| 74 |
else |
| 75 |
cset[0] = 0; |
| 76 |
|
| 77 |
entering = (r->rod > 0.0); /* entering clipped region? */ |
| 78 |
|
| 79 |
for (i = modset[0]; i > 0; i--) |
| 80 |
if (entering) { |
| 81 |
if (!inset(cset, modset[i])) { |
| 82 |
if (cset[0] >= MAXSET) |
| 83 |
error(INTERNAL, "set overflow in m_clip"); |
| 84 |
insertelem(cset, modset[i]); |
| 85 |
} |
| 86 |
} else if (inset(cset, modset[i])) |
| 87 |
deletelem(cset, modset[i]); |
| 88 |
|
| 89 |
/* compute ray value */ |
| 90 |
r->newcset = cset; |
| 91 |
if (strcmp(m->oargs.sarg[0], VOIDID)) { |
| 92 |
int inside = 0; |
| 93 |
const RAY *rp; |
| 94 |
/* check for penetration */ |
| 95 |
for (rp = r; rp->parent != NULL; rp = rp->parent) |
| 96 |
if (!(rp->rtype & RAYREFL) & (rp->parent->ro != NULL) |
| 97 |
&& inset(modset, rp->parent->ro->omod)) { |
| 98 |
if (rp->parent->rod > 0.0) |
| 99 |
inside++; |
| 100 |
else |
| 101 |
inside--; |
| 102 |
} |
| 103 |
if (inside > 0) { /* we just hit the object */ |
| 104 |
flipsurface(r); |
| 105 |
return(rayshade(r, lastmod(obj, m->oargs.sarg[0]))); |
| 106 |
} |
| 107 |
} |
| 108 |
raytrans(r); /* else transfer ray */ |
| 109 |
return(1); |
| 110 |
} |
