Rhino C# 3D Surface and Curve Deformation with Reference, Target, and Constraint Curves

Here's a code sample for deforming 3D surfaces and curves in Rhino C# using reference curves, target curves, and fixed constraint curves:

using Rhino.Geometry;

public void DeformSurfaceWithCurves()
{
    // Get the surface to deform
    Surface surface = ...;

    // Get the reference curves that define the deformation
    Curve[] referenceCurves = ...;

    // Get the target curves that the reference curves will deform to
    Curve[] targetCurves = ...;

    // Get the fixed constraint curves that will not be deformed
    Curve[] fixedCurves = ...;

    // Create a deformation object
    DeformationObject deformation = new DeformationObject(surface);

    // Add the reference curves and target curves to the deformation object
    for (int i = 0; i < referenceCurves.Length; i++)
    {
        Curve referenceCurve = referenceCurves[i];
        Curve targetCurve = targetCurves[i];
        deformation.AddDeformationCurve(referenceCurve, targetCurve);
    }

    // Add the fixed constraint curves to the deformation object
    foreach (Curve fixedCurve in fixedCurves)
    {
        deformation.AddFixedCurve(fixedCurve);
    }

    // Deform the surface
    Surface deformedSurface = deformation.Deform();

    // Do something with the deformed surface
    ...
}

This code assumes you've already obtained the surface, reference curves, target curves, and fixed constraint curves needed for deformation. The DeformationObject class manages the deformation process. You add reference and target curves using AddDeformationCurve(), and fixed constraint curves using AddFixedCurve(). Finally, Deform() applies the deformation and returns the deformed surface.