Create a smooth blend curve connecting the end of one guide curve to the start of another, while passing through a point.

Input parameters:

1. Ca → Guide curve for the start of the blend curve.
2. Cb → Guide curve for the end of the blend curve.
3. Pt → Point through which the blend curve should pass.
4. Bc → Blend continuity.
   • 0 → Position
   • 1 → Tangency
   • 2 → Curvature
   • 3 → G3
   • 4 → G4

Output parameters:

1. Bc → Blend curve connecting both guide curves.