From 1d8235c234e8f559168179972d4a476b1bed82f0 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Mon, 18 May 2020 13:17:26 +0200
Subject: [PATCH] Part: [skip ci] get n-th derivative of a surface via Python

---
 src/Mod/Part/App/GeometrySurfacePy.xml    | 10 +++++
 src/Mod/Part/App/GeometrySurfacePyImp.cpp | 46 +++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/src/Mod/Part/App/GeometrySurfacePy.xml b/src/Mod/Part/App/GeometrySurfacePy.xml
index 16fbc7135e..a15a2d63fd 100644
--- a/src/Mod/Part/App/GeometrySurfacePy.xml
+++ b/src/Mod/Part/App/GeometrySurfacePy.xml
@@ -22,6 +22,16 @@
 				<UserDocu>Return the shape for the geometry.</UserDocu>
 			</Documentation>
 		</Methode>
+        <Methode Name="getD0" Const="true">
+            <Documentation>
+                <UserDocu>Returns the point of given parameter</UserDocu>
+            </Documentation>
+        </Methode>
+        <Methode Name="getDN" Const="true">
+            <Documentation>
+                <UserDocu>Returns the n-th derivative</UserDocu>
+            </Documentation>
+        </Methode>
         <Methode Name="value" Const="true">
 			<Documentation>
                 <UserDocu>value(u,v) -> Point
diff --git a/src/Mod/Part/App/GeometrySurfacePyImp.cpp b/src/Mod/Part/App/GeometrySurfacePyImp.cpp
index 5dd47e04c8..a75a0a961d 100644
--- a/src/Mod/Part/App/GeometrySurfacePyImp.cpp
+++ b/src/Mod/Part/App/GeometrySurfacePyImp.cpp
@@ -281,6 +281,52 @@ PyObject* GeometrySurfacePy::toShape(PyObject *args)
     return 0;
 }
 
+PyObject* GeometrySurfacePy::getD0(PyObject *args)
+{
+    Handle(Geom_Geometry) g = getGeometryPtr()->handle();
+    Handle(Geom_Surface) s = Handle(Geom_Surface)::DownCast(g);
+    try {
+        if (!s.IsNull()) {
+            double u,v;
+            if (!PyArg_ParseTuple(args, "dd", &u, &v))
+                return nullptr;
+            gp_Pnt p;
+            s->D0(u, v, p);
+            return new Base::VectorPy(Base::Vector3d(p.X(),p.Y(),p.Z()));
+        }
+    }
+    catch (Standard_Failure& e) {
+        PyErr_SetString(PartExceptionOCCError, e.GetMessageString());
+        return nullptr;
+    }
+
+    PyErr_SetString(PartExceptionOCCError, "Geometry is not a surface");
+    return nullptr;
+}
+
+PyObject* GeometrySurfacePy::getDN(PyObject *args)
+{
+    Handle(Geom_Geometry) g = getGeometryPtr()->handle();
+    Handle(Geom_Surface) s = Handle(Geom_Surface)::DownCast(g);
+    try {
+        if (!s.IsNull()) {
+            int nu, nv;
+            double u,v;
+            if (!PyArg_ParseTuple(args, "ddii", &u, &v, &nu, &nv))
+                return nullptr;
+            gp_Vec v1 = s->DN(u, v, nu, nv);
+            return new Base::VectorPy(Base::Vector3d(v1.X(),v1.Y(),v1.Z()));
+        }
+    }
+    catch (Standard_Failure& e) {
+        PyErr_SetString(PartExceptionOCCError, e.GetMessageString());
+        return nullptr;
+    }
+
+    PyErr_SetString(PartExceptionOCCError, "Geometry is not a surface");
+    return nullptr;
+}
+
 PyObject* GeometrySurfacePy::value(PyObject *args)
 {
     Handle(Geom_Geometry) g = getGeometryPtr()->handle();