ON_3dVector ON_Ellipse::CurvatureAt(
double t // parameter
) const
{
ON_3dVector T, K;
ON_EvCurvature(DerivativeAt( 1, t ),DerivativeAt( 2, t ),T,K);
return K;
}
bool ON_Surface::GetNextDiscontinuity(
int dir,
ON::continuity c,
double t0,
double t1,
double* t,
int* hint,
int* dtype,
double cos_angle_tolerance,
double curvature_tolerance
) const
{
// 28 Jan 2005 - untested code
// this function must be overridden by surface objects that
// can have parametric discontinuities on the interior of the curve.
bool rc = false;
// using tmp_dtype means I don't have to keep checking for a null dtype;
int tmp_dtype = 0;
if ( !dtype )
dtype = &tmp_dtype;
*dtype = 0;
if ( t0 != t1 )
{
bool bTestC0 = false;
bool bTestD1 = false;
bool bTestD2 = false;
bool bTestT = false;
bool bTestK = false;
switch(c)
{
case ON::C0_locus_continuous:
bTestC0 = true;
break;
case ON::C1_locus_continuous:
bTestC0 = true;
bTestD1 = true;
break;
case ON::C2_locus_continuous:
bTestC0 = true;
bTestD1 = true;
bTestD2 = true;
break;
case ON::G1_locus_continuous:
bTestC0 = true;
bTestT = true;
break;
case ON::G2_locus_continuous:
bTestC0 = true;
bTestT = true;
bTestK = true;
break;
default:
// other values ignored on purpose.
break;
}
if ( bTestC0 )
{
// 20 March 2003 Dale Lear:
// Have to look for locus discontinuities at ends.
// Must test both ends becuase t0 > t1 is valid input.
// In particular, for ON_CurveProxy::GetNextDiscontinuity()
// to work correctly on reversed "real" curves, the
// t0 > t1 must work right.
int hinta[2], hintb[2], span_index, j;
ON_Interval domain = Domain(dir);
ON_Interval span_domain;
ON_2dPoint st0, st1;
ON_3dVector Da[6], Db[6];
ON_3dVector& D1a = Da[1+dir];
ON_3dVector& D1b = Db[1+dir];
ON_3dVector& D2a = Da[3+2*dir];
ON_3dVector& D2b = Db[3+2*dir];
if ( t0 < domain[1] && t1 >= domain[1] )
t1 = domain[1];
else if ( t0 > domain[0] && t1 <= domain[0] )
t1 = domain[0];
if ( (t0 < domain[1] && t1 >= domain[1]) || (t0 > domain[0] && t1 <= domain[0]) )
{
if ( IsClosed(dir) )
{
int span_count = SpanCount(1-dir);
double* span_vector = (span_count>0) ? ((double*)onmalloc((span_count+1)*sizeof(*span_vector))) : 0;
if (!GetSpanVector(1-dir,span_vector))
span_count = 0;
st0[dir] = domain[0];
st1[dir] = domain[1];
for ( span_index = 0; span_index < span_count && 1 != *dtype; span_index++ )
{
span_domain.Set(span_vector[span_index],span_vector[span_index+1]);
for ( j = (span_index?1:0); j <= 2 && 1 != *dtype; j++ )
{
st0[1-dir] = span_domain.ParameterAt(0.5*j);
st1[1-dir] = st0[1-dir];
if ( bTestD1 || bTestT )
{
// need to check locus continuity at start/end of closed surface.
if ( Evaluate(st0.x,st0.y,2,3,&Da[0].x,1,hinta)
&& Evaluate(st1.x,st1.y,2,3,&Db[0].x,2,hintb) )
{
if ( bTestD1 )
{
if ( !(D1a-D1b).IsTiny(D1b.MaximumCoordinate()*ON_SQRT_EPSILON ) )
{
if ( dtype )
*dtype = 1;
*t = t1;
rc = true;
}
else if ( bTestD2 && !(D2a-D2b).IsTiny(D2b.MaximumCoordinate()*ON_SQRT_EPSILON) )
{
if ( dtype )
*dtype = 2;
*t = t1;
rc = true;
}
}
else if ( bTestT )
{
ON_3dVector Ta, Tb, Ka, Kb;
ON_EvCurvature( D1a, D2a, Ta, Ka );
ON_EvCurvature( D1b, D2b, Tb, Kb );
if ( Ta*Tb < cos_angle_tolerance )
{
if ( dtype )
*dtype = 1;
*t = t1;
rc = true;
}
else if ( bTestK && (Ka-Kb).Length() > curvature_tolerance )
{
if ( dtype )
*dtype = 2;
*t = t1;
rc = true;
}
}
}
}
}
}
if ( span_vector)
{
onfree(span_vector);
}
}
else
{
// open curves are not locus continuous at ends.
*dtype = 0; // locus C0 discontinuity
*t = t1;
rc = true;
}
}
}
}
return rc;
}
