// clip the segments of e by the planes of polyhedron a.
void clip_segments(const polyhedron &ph, MySegments &is, MySegments &os)
{
const MyArrayPoly &p = ph.p;
for (unsigned int i = 0; i < is.size(); i+=2) {
idVec4 a = is[i ];
idVec4 b = is[i+1];
idVec4 c;
bool discard = false;
for (unsigned int j = 0; j < p.size(); j++) {
float da = a * p[j].plane;
float db = b * p[j].plane;
float rdw = 1/(da - db);
int code = 0;
if (da > 0)
code = 2;
if (db > 0)
code |= 1;
switch (code) {
case 3:
discard = true;
break;
case 2:
c = -db * rdw * a + da * rdw * b;
a = c;
break;
case 1:
c = -db * rdw * a + da * rdw * b;
b = c;
break;
case 0:
break;
default:
common->Printf("bad clip code!\n");
break;
}
if (discard)
break;
}
if (! discard) {
os.push_back(a);
os.push_back(b);
}
}
}
void polyhedron_edges( polyhedron &a, MySegments &e ) {
e.empty();
if( a.e.size() == 0 && a.p.size() != 0 ) {
a.compute_neighbors();
}
for( unsigned int i = 0; i < a.e.size(); i++ ) {
e.push_back( a.v[a.e[i].vi[0]] );
e.push_back( a.v[a.e[i].vi[1]] );
}
}