// =============================================================================
bool Mesh2DUtils::identify_patch_upper_right(const Mesh2D&m, double u,
double v, int& x_ix, int& y_ix)
// =============================================================================
{
double tol = 1.0e-9;
x_ix = first_larger_knotvalue_ix(m, XFIXED, u);
y_ix = first_larger_knotvalue_ix(m, YFIXED, v);
// adjustment of index if positioned _exactly_ at upper bound of grid
if ((x_ix == m.numDistinctKnots(XFIXED) - 1) && (fabs(u-m.maxParam(XFIXED) < tol)))
--x_ix;
if ((y_ix == m.numDistinctKnots(YFIXED) - 1) && (fabs(v-m.maxParam(YFIXED) < tol)))
--y_ix;
// checking if a valid corner was found
if (x_ix == 0 || x_ix >= m.numDistinctKnots(XFIXED)) return false; // u outside domain
if (y_ix == 0 || y_ix >= m.numDistinctKnots(YFIXED)) return false; // v outside domain
// We have now found the largest smaller knot in the u and v direction. From here we
// can search downwards to the lower-left corner of the containing mesh element, which
// defines the sought-for "patch" of the surface.
x_ix = search_upwards_for_nonzero_multiplicity(m, XFIXED, x_ix, y_ix);
y_ix = search_upwards_for_nonzero_multiplicity(m, YFIXED, y_ix, x_ix);
return true;
}
// =============================================================================
int Mesh2DUtils::first_larger_knotvalue_ix(const Mesh2D& m, Direction2D d,
double par)
// =============================================================================
{
int ix = last_nonlarger_knotvalue_ix(m, d, par);
if (ix < m.numDistinctKnots(d)-1)
ix++;
return ix;
}
//==============================================================================
int Mesh2DUtils::search_upwards_for_nonzero_multiplicity(const Mesh2D& m,
Direction2D d,
int start_ix, int other_ix)
//==============================================================================
{
// provided that the mesh is a valid LR mesh, a valid index should always be found.
int ix;
for (ix = start_ix; ix != m.numDistinctKnots(d) && m.nu(d, ix, other_ix - 1, other_ix) == 0; ++ix);
return ix; // @@ not yet tested!
}