Curve evalBezier( const vector< Vec3f >& P, unsigned steps )
{
// Check
if( P.size() < 4 || P.size() % 3 != 1 )
{
cerr << "evalBezier must be called with 3n+1 control points." << endl;
exit( 0 );
}
cerr << "\t>>> evalBezier has been called with the following input:" << endl;
cerr << "\t>>> Control points (type vector< Vec3f >): "<< endl;
for( unsigned i = 0; i < P.size(); ++i )
{
cerr << "\t>>> "; printTranspose(P[i]); cerr << endl;
}
cerr << "\t>>> Steps (type steps): " << steps << endl;
// Return value: initialize with starting values. Note the
// initial normal of [0,1,0] will result in the
// "counterclockwise" specification for 2D curves on the xy-plane.
// I.e., the normal of the curve is facing left from the
// direction of travel. For 3D curves, the choice of direction is
// kind of arbitrary. so this initial normal works too.
vector< Vec3f >::const_iterator segmentStart = P.begin();
vector< Vec3f >::const_iterator segmentEnd = P.size() > 4 ?
P.begin() + 4 :
P.end();
Curve R
(
coreBezier
(
P[0], P[1], P[2], P[3],
Vec3f( 0, 0, 1 ),
steps
)
);
// Build the rest of the curve
for( unsigned i = 0; i < ( P.size() - 4 ) / 3; ++i )
{
Vec3f p0 = P[ 3 * i + 3 ];
Vec3f p1 = P[ 3 * i + 4 ];
Vec3f p2 = P[ 3 * i + 5 ];
Vec3f p3 = P[ 3 * i + 6 ];
vector< CurvePoint > Rnew
(
coreBezier
(
p0, p1, p2, p3,
R.back().B, // init with previous computed binormal
steps
)
);
R.pop_back();
R.insert( R.end(), Rnew.begin(), Rnew.end() );
}
// Finally, check for loop and patch ends
if( approx( R.front().V, R.back().V ) &&
approx( R.front().T, R.back().T ) &&
!approx( R.front().N, R.back().N )
)
{
Vec3f axis = R.front().N.cross(R.back().N);
float angle = FW::acos( dot( R.front().N, R.back().N ) );
float sign = ( dot( axis, R.front().T ) > 0 ) ? 1.f : -1.f;
for( unsigned i = 0; i < R.size(); ++i )
{
float d = float( i ) / ( R.size() - 1 );
Mat3f M = Mat3f::rotation( R[i].T, -sign * d * angle );
R[i].N = M * R[i].N;
R[i].B = M * R[i].B;
}
}
return R;
}
