bool CRhGetPolylineSegment::CalculatePolylineSegment( const ON_3dPoint& pt, int& index0, int& index1 )
{
if( 0 == m_curve )
return false;
index0 = index1 = -1;
double t = 0.0;
if( m_curve->GetClosestPoint(pt, &t) )
{
int count = m_curve->m_t.Count();
index0 = ON_SearchMonotoneArray( m_curve->m_t, count, t );
if( index0 >= 0 && index0 <= count - 1 )
{
if( index0 == count - 1 )
{
if( m_curve->IsClosed() )
index1 = 0;
else
{
index0 = count - 2;
index1 = count - 1;
}
}
else
index1 = m_index0 + 1;
return true;
}
}
return false;
}
int ON_NurbsSpanIndex(
int order, // (>=2)
int cv_count,
const double* knot, // knot[] array or length ON_KnotCount(order,cv_count)
double t, // evaluation parameter
int side, // side 0 = default, -1 = from below, +1 = from above
int hint // hint (or 0 if no hint available)
)
{
int j, len;
// shift knot so that domain is knot[0] to knot[len]
knot += (order-2);
len = cv_count-order+2;
// see if hint helps
if (hint > 0 && hint < len-1) {
while(hint > 0 && knot[hint-1] == knot[hint]) hint--;
if (hint > 0) {
// have knot[hint-1] < knot[hint]
if (t < knot[hint]) {
len = hint+1;
hint = 0;
}
else {
if (side < 0 && t == knot[hint])
hint--;
knot += hint;
len -= hint;
}
}
}
else
hint = 0;
j = ON_SearchMonotoneArray(knot,len,t);
if (j < 0)
j = 0;
else if (j >= len-1)
j = len-2;
else if (side < 0) {
// if user wants limit from below and t = an internal knot,
// back up to prevous span
while(j > 0 && t == knot[j])
j--;
}
return (j + hint);
}
ON_BOOL32
ON_LocalZero1::BracketSpan( double s0, double f0, double s1, double f1 )
{
int i0, i1, i;
double fm, fp;
ON_BOOL32 rc = true;
if ( m_k && m_k_count >= 3 ) {
i0 = ON_SearchMonotoneArray(m_k,m_k_count,s0);
if ( i0 < 0 )
i0 = 0;
i1 = ON_SearchMonotoneArray(m_k,m_k_count,s1);
if ( i1 >= m_k_count )
i1 = m_k_count-1;
while ( i1 >= 0 && s1 == m_k[i1] ) {
i1--;
}
i0++;
while ( i0 < m_k_count-1 && m_k[i0] == m_k[i0+1] )
i0++;
if ( i0 <= i1 ) {
// we have s0 < m_k[i0] <= ... <= m_k[i1] < s1
Evaluate( m_k[i0], &fm, NULL,-1 ); // gaurd against C0 discontinuities
Evaluate( m_k[i0], &fp, NULL, 1 );
if ( (f0 <= 0.0 && fm >= 0.0) || (f0 >= 0.0 && fm <= 0.0) ) {
m_s1 = m_k[i0];
m_f1 = fm;
}
else if ( (f1 <= 0.0 && fp >= 0.0) || (f1 >= 0.0 && fp <= 0.0) ) {
m_s0 = m_k[i0];
m_f0 = fp;
if ( i0 < i1 ) {
Evaluate( m_k[i1], &fm, NULL, -1 );
Evaluate( m_k[i1], &fp, NULL, 1 );
if ( (f1 <= 0.0 && fp >= 0.0) || (f1 >= 0.0 && fp <= 0.0) ) {
m_s0 = m_k[i1];
m_f0 = fp;
}
else if ( (f0 <= 0.0 && fm >= 0.0) || (f0 >= 0.0 && fm <= 0.0) ) {
m_s1 = m_k[i1];
m_f1 = fm;
// we have s0 = m_k[i0] < m_k[i1] = s1 and a bonafide sign change
while (i0+1 < i1) {
// bisect m_k[i0],...,m_k[i1] until we get a sign change between
// m_k[i],m_k[i+1]. We need to do this in order to make sure
// we are passing a C2 function to the repeated zero finders.
i = (i0+i1)>>1;
Evaluate( m_k[i], &fm, NULL, -1 );
Evaluate( m_k[i], &fp, NULL, 1 );
if ( (f0 <= 0.0 && fm >= 0.0) || (f0 >= 0.0 && fm <= 0.0) ) {
m_s1 = m_k[i];
m_f1 = fm;
i1 = i;
while ( i1>0 && m_k[i1-1]==m_k[i1])
i1--;
}
else if ( (f1 <= 0.0 && fp >= 0.0) || (f1 >= 0.0 && fp <= 0.0) ) {
m_s0 = m_k[i];
m_f0 = fp;
i0 = i;
while ( i0 < m_k_count-2 && m_k[i0] == m_k[i0+1] )
i0++;
}
else {
// discontinuous sign change across m_k[i]
rc = false;
break;
}
}
}
