"Unify nurbs surfaces" API.

utils/surface/algorithms.py

@@ -21,6 +21,7 @@
     )
 from sverchok.utils.curve.core import SvFlipCurve, UnsupportedCurveTypeException
 from sverchok.utils.curve.primitives import SvCircle
+from sverchok.utils.curve import knotvector as sv_knotvector
 from sverchok.utils.curve.algorithms import (
             SvNormalTrack, curve_frame_on_surface_array,
             MathutilsRotationCalculator, DifferentialRotationCalculator,
@@ -1072,3 +1073,61 @@ def nurbs_revolution_surface(curve, origin, axis, v_min=0, v_max=2*pi, global_or
             curve.get_knotvector(), circle_knotvector,
             control_points, weights)
 
+def unify_nurbs_surfaces(surfaces):
+    # Unify surface degrees
+
+    degrees_u = [surface.get_degree_u() for surface in surfaces]
+    degrees_v = [surface.get_degree_v() for surface in surfaces]
+
+    degree_u = max(degrees_u)
+    degree_v = max(degrees_v)
+
+    surfaces = [surface.elevate_degree(SvNurbsSurface.U, target=degree_u) for surface in surfaces]
+    surfaces = [surface.elevate_degree(SvNurbsSurface.V, target=degree_v) for surface in surfaces]
+
+    # Unify surface knotvectors
+
+    dst_knots_u = defaultdict(int)
+    dst_knots_v = defaultdict(int)
+    for surface in surfaces:
+        m_u = sv_knotvector.to_multiplicity(surface.get_knotvector_u())
+        m_v = sv_knotvector.to_multiplicity(surface.get_knotvector_v())
+
+        for u, count in m_u:
+            u = round(u, 6)
+            dst_knots_u[u] = max(dst_knots_u[u], count)
+
+        for v, count in m_v:
+            v = round(v, 6)
+            dst_knots_v[v] = max(dst_knots_v[v], count)
+
+    result = []
+    for surface in surfaces:
+        diffs_u = []
+        kv_u = np.round(surface.get_knotvector_u(), 6)
+        ms_u = dict(sv_knotvector.to_multiplicity(kv_u))
+        for dst_u, dst_multiplicity in dst_knots_u.items():
+            src_multiplicity = ms_u.get(dst_u, 0)
+            diff = dst_multiplicity - src_multiplicity
+            diffs_u.append((dst_u, diff))
+
+        for u, diff in diffs_u:
+            if diff > 0:
+                surface = surface.insert_knot(SvNurbsSurface.U, u, diff)
+
+        diffs_v = []
+        kv_v = np.round(surface.get_knotvector_v(), 6)
+        ms_v = dict(sv_knotvector.to_multiplicity(kv_v))
+        for dst_v, dst_multiplicity in dst_knots_v.items():
+            src_multiplicity = ms_v.get(dst_v, 0)
+            diff = dst_multiplicity - src_multiplicity
+            diffs_v.append((dst_v, diff))
+
+        for v, diff in diffs_v:
+            if diff > 0:
+                surface = surface.insert_knot(SvNurbsSurface.V, v, diff)
+
+        result.append(surface)
+
+    return result
+