Point2F BiQuadToSqr::transform( const Point2F &p ) const
{
Point2F kA = m_kP00 - p;
F32 fAB = mDotPerp( kA, m_kB );
F32 fAC = mDotPerp( kA, m_kC);
// 0 = ac*bc+(bc^2+ac*bd-ab*cd)*s+bc*bd*s^2 = k0 + k1*s + k2*s^2
F32 fK0 = fAC*m_fBC;
F32 fK1 = m_fBC*m_fBC + fAC*m_fBD - fAB*m_fCD;
F32 fK2 = m_fBC*m_fBD;
if (mFabs(fK2) > POINT_EPSILON)
{
// s-equation is quadratic
F32 fInv = 0.5f/fK2;
F32 fDiscr = fK1*fK1 - 4.0f*fK0*fK2;
F32 fRoot = mSqrt( mFabs(fDiscr) );
Point2F kResult0( 0, 0 );
kResult0.x = (-fK1 - fRoot)*fInv;
kResult0.y = fAB/(m_fBC + m_fBD*kResult0.x);
F32 fDeviation0 = deviation(kResult0);
if ( fDeviation0 == 0.0f )
return kResult0;
Point2F kResult1( 0, 0 );
kResult1.x = (-fK1 + fRoot)*fInv;
kResult1.y = fAB/(m_fBC + m_fBD*kResult1.x);
F32 fDeviation1 = deviation(kResult1);
if ( fDeviation1 == 0.0f )
return kResult1;
if (fDeviation0 <= fDeviation1)
{
if ( fDeviation0 < POINT_EPSILON )
return kResult0;
}
else
{
if ( fDeviation1 < POINT_EPSILON )
return kResult1;
}
}
else
{
// s-equation is linear
Point2F kResult( 0, 0 );
kResult.x = -fK0/fK1;
kResult.y = fAB/(m_fBC + m_fBD*kResult.x);
F32 fDeviation = deviation(kResult);
if ( fDeviation < POINT_EPSILON )
return kResult;
}
// point is outside the quadrilateral, return invalid
return Point2F(F32_MAX,F32_MAX);
}
BiQuadToSqr::BiQuadToSqr( const Point2F &p00,
const Point2F &p10,
const Point2F &p11,
const Point2F &p01 )
: m_kP00( p00 )
{
m_kB = p10 - p00; // width
m_kC = p01 - p00; // height
m_kD = p11 + p00 - p10 - p01; // diagonal dist
m_fBC = mDotPerp( m_kB, m_kC );
m_fBD = mDotPerp( m_kB, m_kD );
m_fCD = mDotPerp( m_kC, m_kD );
}
BiQuadToSqr::BiQuadToSqr( const Point2F &p00,
const Point2F &p10,
const Point2F &p11,
const Point2F &p01 )
: m_kP00( p00 )
{
m_kB = p10 - p00 ; // width
m_kC = p01 - p00; // height
m_kD = p11 + p00 - p10 - p01; // diagonal dist
if(mFabs(m_kD.x) < POINT_EPSILON)
m_kD.x = 0.f;
if(mFabs(m_kD.y) < POINT_EPSILON)
m_kD.y = 0.f;
m_fBC = mDotPerp( m_kB, m_kC );
m_fBD = mDotPerp( m_kB, m_kD );
m_fCD = mDotPerp( m_kC, m_kD );
}
