/// Implementation derived from Wild Magic (Version 2) Software Library, available
/// from http://www.geometrictools.com/Downloads/WildMagic2p5.zip under free license
int SpherePrimitiveEvaluator::intersectionPoints( const Imath::V3f &origin, const Imath::V3f &direction,
std::vector<PrimitiveEvaluator::ResultPtr> &results, float maxDistance ) const
{
results.clear();
Imath::V3f dir = direction.normalized();
(void)direction;
float a0 = origin.dot(origin) - m_sphere->radius() * m_sphere->radius();
float a1 = dir.dot( origin );
float discr = a1 * a1 - a0;
if (discr < 0.0)
{
return 0;
}
if ( discr >= Imath::limits<float>::epsilon() )
{
float root = sqrt( discr );
float t0 = -a1 - root;
if ( t0 >= 0.0 )
{
Imath::V3f p0 = origin + t0 * dir;
if ( (origin - p0).length() < maxDistance )
{
ResultPtr r = staticPointerCast< Result > ( createResult() );
r->m_p = p0;
results.push_back( r );
}
}
float t1 = -a1 + root;
if ( t1 >= 0.0 )
{
Imath::V3f p1 = origin + t1 * dir;
if ( (origin - p1).length() < maxDistance )
{
ResultPtr r = staticPointerCast< Result > ( createResult() );
r->m_p = p1;
results.push_back( r );
}
}
}
else
{
float t = -a1;
if ( t >= 0.0 )
{
Imath::V3f p = origin + t * dir;
if ( (origin - p).length() < maxDistance )
{
ResultPtr r = staticPointerCast< Result > ( createResult() );
r->m_p = p;
results.push_back( r );
}
}
}
assert( results.size() >= 0 );
assert( results.size() <= 2 );
return results.size();
}
/// Implementation derived from Wild Magic (Version 2) Software Library, available
/// from http://www.geometrictools.com/Downloads/WildMagic2p5.zip under free license
bool SpherePrimitiveEvaluator::intersectionPoint( const Imath::V3f &origin, const Imath::V3f &direction,
PrimitiveEvaluator::Result *result, float maxDistance ) const
{
assert( dynamic_cast<Result *>( result ) );
Result *sr = static_cast<Result *>( result );
Imath::V3f dir = direction.normalized();
(void)direction;
float a0 = origin.dot( origin ) - m_sphere->radius() * m_sphere->radius();
float a1 = dir.dot( origin );
float discr = a1 * a1 - a0;
if (discr < 0.0)
{
return false;
}
if ( discr >= Imath::limits<float>::epsilon() )
{
float root = sqrt( discr );
float t0 = -a1 - root;
float t1 = -a1 + root;
Imath::V3f p0 = origin + t0 * dir;
Imath::V3f p1 = origin + t1 * dir;
if ( t0 >= 0.0 )
{
if ( t1 >= 0.0 )
{
if ( (origin - p0).length2() < ( origin - p1 ).length2() )
{
sr->m_p = p0;
}
else
{
sr->m_p = p1;
}
}
else
{
sr->m_p = p0;
}
}
else if ( t1 >= 0.0 )
{
sr->m_p = p1;
}
else
{
return false;
}
}
else
{
float t = -a1;
if ( t >= 0.0 )
{
sr->m_p = origin + t * dir;
}
else
{
return false;
}
}
if ( (sr->m_p - origin).length() < maxDistance)
{
return true;
}
return false;
}
