Lookup the u-value along a BoundaryEdge, with respect to given opposite BezierVertex.
Clearly, we must be a vertex on a constraint edge: it is an error to call this function on a D2 vertex.
If this BezierVertex is a D1 vertex, then the u-value is known already, so return it.
If this BezierVertex is a D0 vertex, then there are possibly many BoundaryEdges for it to have a u-value on. We take the BoundaryEdge given to us as the edge on which to find the u-value.
However, if the BoundaryEdge is a self-loop then this BezierVertex will be the first and last vertex along the spline, and so have two valid u-values. Thus, we take the opposite vertex as well, which is the BezierVertex right before, or right after this vertex in the parametrization of the spline. Thus if we want the u-value with this BezierVertex as the last in the parametrization, then opposite should be the second to last vertex.
- Parameters:
-
| be | The BoundaryEdge along which the u-value is requested |
| opposite | The vertex immediately before or after this vertex in parametrization |
- Returns:
- The u-value along the BoundaryEdge, with respect to the given opposite vertex
Definition at line 982 of file cell.C.
References QBSpline::closed, containment_dimension(), QBSpline::evaluate(), get_cp(), BoundaryEdge::get_spline(), get_u(), QBSpline::k, and QBSpline::vertexs.
Referenced by BezierMesh::insert_edge_midpoint(), operator<<(), and BezierMesh::remove_vertex().
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