//----------------------------------------------------------------------------
int BspTree2::Classify (const Vector2d& end0, const Vector2d& end1,
const Vector2d& vertex) const
{
// For numerical round-off error handling.
const double epsilon = 0.00001;
Vector2d dir = end1 - end0;
Vector2d nor = dir.Perp();
Vector2d diff = vertex - end0;
double c = nor.Dot(diff);
if (c > epsilon)
{
return ALL_POSITIVE;
}
if (c < -epsilon)
{
return ALL_NEGATIVE;
}
return COINCIDENT;
}
//----------------------------------------------------------------------------
int BspTree2::Classify (const Vector2d& end0, const Vector2d& end1,
const Vector2d& v0, const Vector2d& v1, Vector2d& intr) const
{
// For numerical round-off error handling.
const double epsilon0 = 0.00001;
const double epsilon1 = 0.99999;
Vector2d dir = end1 - end0;
Vector2d nor = dir.Perp();
Vector2d diff0 = v0 - end0;
Vector2d diff1 = v1 - end0;
double d0 = nor.Dot(diff0);
double d1 = nor.Dot(diff1);
if (d0*d1 < 0.0)
{
// Edge <V0,V1> transversely crosses line. Compute point of
// intersection I = V0 + t*(V1 - V0).
double t = d0/(d0 - d1);
if (t > epsilon0)
{
if (t < epsilon1)
{
intr = v0 + t*(v1 - v0);
if (d1 > 0.0)
{
return TRANSVERSE_POSITIVE;
}
else
{
return TRANSVERSE_NEGATIVE;
}
}
else
{
// T is effectively 1 (numerical round-off issue), so
// set d1 = 0 and go on to other cases.
d1 = 0.0;
}
}
else
{
// T is effectively 0 (numerical round-off issue), so
// set d0 = 0 and go on to other cases.
d0 = 0.0;
}
}
if (d0 > 0.0 || d1 > 0.0)
{
// edge on positive side of line
return ALL_POSITIVE;
}
if (d0 < 0.0 || d1 < 0.0)
{
// edge on negative side of line
return ALL_NEGATIVE;
}
return COINCIDENT;
}
