//returns the number of resulting intervals
//if 1, returns it in p
//if 2, returns them in p and q
int IntervalSubtract(const ClosedInterval& a,const OpenInterval& b,ClosedInterval& p,ClosedInterval& q)
{
if(a.intersects(b)) {
if(a.contains(b.a) && a.contains(b.b)) {
p.a=a.a; p.b=b.a;
q.a=b.b; q.b=a.b;
return 2;
}
else if(a.contains(b.a)) {
p.a=a.a; p.b=b.a;
return 1;
}
else if(a.contains(b.b)) {
p.a=b.b; p.b=a.b;
return 1;
}
else {
Assert(b.contains(a.a) && b.contains(a.b));
return 0;
}
}
else {
p=a;
return 1;
}
}
bool HollowBall::containsSphere(const Sphere3D& s) const
{
Real d = s.center.distance(center);
ClosedInterval i;
i.a = Max(innerRadius,Zero);
i.b = outerRadius;
return i.contains(d-s.radius) && i.contains(d+s.radius);
}
bool ConvexPolyhedron3D::planeSplits(const Plane3D& p) const
{
ClosedInterval x;
x.setEmpty();
Real vpos;
for(int i=0; i<numVertices; i++)
{
vpos = p.distance(vertices[i]);
x.expand(vpos);
if(x.contains(Zero))
return true;
}
return false;
}