Splines backed by rational NURBS (circles, conics) were tessellated as
uniform B-splines, losing the weighting that defines the curve shape.
Now BSplineCurve<Point3> is used only when weights are absent or empty;
when weight data is present a NurbsCurve<Vector4> is built from the
homogeneous control points so circles and conics render accurately.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Spline: if flags.closed/periodic and B-spline endpoints don't meet,
add an explicit closing Wire segment to eliminate the visual gap.
- Hatch BoundaryEdge::Spline: evaluate the B-spline at 16 uniform
parameter samples (de Boor via truck BSplineCurve) instead of
plotting raw control points as a polyline; falls back to control-
point polyline for degenerate knot/degree inputs.
- Ellipse arc key_vertices and LWPolyline midpoint grips committed
separately; this commit wraps the spline-related fixes.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Spline entities now expose fit_points (or control_points when no fit
points are defined) as key_vertices, enabling Endpoint and Midpoint
snap to reach spline construction points.
TextStyle is_backward flag is applied by negating the width_factor,
producing horizontally mirrored text. is_upside_down rotates the text
180°. Both tessellate_text_ex and text_local_bounds now handle negative
width_factor without clamping it to zero.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Empty LwPolyline and single-control-point Spline fallbacks were calling
builder::line(&v, &v) with the same Rc vertex, triggering the
truck-topology panic "Two same vertices cannot construct an edge."
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
