Add Bézier curve support to Workplane and Sketch (#1529)

cadquery/cq.py

@@ -1629,6 +1629,39 @@ class Workplane(object):
 
         return self.newObject([p])
 
+    def bezier(
+        self: T,
+        listOfXYTuple: Iterable[VectorLike],
+        forConstruction: bool = False,
+        includeCurrent: bool = False,
+        makeWire: bool = False,
+    ) -> T:
+        """
+        Make a cubic Bézier curve by the provided points (2D or 3D).
+
+        :param listOfXYTuple: Bezier control points and end point.
+            All points except the last point are Bezier control points,
+            and the last point is the end point
+        :param includeCurrent: Use the current point as a starting point of the curve
+        :param makeWire: convert the resulting bezier edge to a wire
+        :return: a Workplane object with the current point at the end of the bezier
+
+        The Bézier Will begin at either current point or the first point
+        of listOfXYTuple, and end with the last point of listOfXYTuple
+        """
+        allPoints = self._toVectors(listOfXYTuple, includeCurrent)
+
+        e = Edge.makeBezier(allPoints)
+
+        if makeWire:
+            rv_w = Wire.assembleEdges([e])
+            if not forConstruction:
+                self._addPendingWire(rv_w)
+        elif not forConstruction:
+            self._addPendingEdge(e)
+
+        return self.newObject([rv_w if makeWire else e])
+
     # line a specified incremental amount from current point
     def line(self: T, xDist: float, yDist: float, forConstruction: bool = False) -> T:
         """

cadquery/occ_impl/shapes.py

@@ -56,7 +56,7 @@ from OCP.gp import (
 )
 
 # Array of points (used for B-spline construction):
-from OCP.TColgp import TColgp_HArray1OfPnt, TColgp_HArray2OfPnt
+from OCP.TColgp import TColgp_HArray1OfPnt, TColgp_HArray2OfPnt, TColgp_Array1OfPnt
 
 # Array of vectors (used for B-spline interpolation):
 from OCP.TColgp import TColgp_Array1OfVec
@@ -146,6 +146,7 @@ from OCP.BRepAlgoAPI import (
 )
 
 from OCP.Geom import (
+    Geom_BezierCurve,
     Geom_ConicalSurface,
     Geom_CylindricalSurface,
     Geom_Surface,
@@ -2091,6 +2092,26 @@ class Edge(Shape, Mixin1D):
             BRepBuilderAPI_MakeEdge(Vector(v1).toPnt(), Vector(v2).toPnt()).Edge()
         )
 
+    @classmethod
+    def makeBezier(cls, points: List[Vector]) -> "Edge":
+        """
+        Create a cubic Bézier Curve from the points.
+
+        :param points: a list of Vectors that represent the points.
+            The edge will pass through the first and the last point,
+            and the inner points are Bézier control points.
+        :return: An edge
+        """
+
+        # Convert to a TColgp_Array1OfPnt
+        arr = TColgp_Array1OfPnt(1, len(points))
+        for i, v in enumerate(points):
+            arr.SetValue(i + 1, Vector(v).toPnt())
+
+        bez = Geom_BezierCurve(arr)
+
+        return cls(BRepBuilderAPI_MakeEdge(bez).Edge())
+
 
 class Wire(Shape, Mixin1D):
     """

cadquery/sketch.py

@@ -859,6 +859,23 @@ class Sketch(object):
 
         return self.spline(pts, None, False, tag, forConstruction)
 
+    def bezier(
+        self: T,
+        pts: Iterable[Point],
+        tag: Optional[str] = None,
+        forConstruction: bool = False,
+    ) -> T:
+        """
+        Construct an bezier curve.
+
+        The edge will pass through the last points, and the inner points
+        are bezier control points.
+        """
+        p1 = self._endPoint()
+        val = Edge.makeBezier([Vector(*p) for p in pts])
+
+        return self.edge(val, tag, forConstruction)
+
     def close(self: T, tag: Optional[str] = None) -> T:
         """
         Connect last edge to the first one.

tests/test_sketch.py

@@ -470,6 +470,19 @@ def test_edge_interface():
     assert len(s6.vertices()._selection) == 1
 
 
+def test_bezier():
+    s1 = (
+        Sketch()
+        .segment((0, 0), (0, 0.5))
+        .bezier(((0, 0.5), (-1, 2), (1, 0.5), (5, 0)))
+        .bezier(((5, 0), (1, -0.5), (-1, -2), (0, -0.5)))
+        .close()
+        .assemble()
+    )
+    assert s1._faces.Area() == approx(5.35)
+    # What other kind of tests can we do?
+
+
 def test_assemble():
 
     s1 = Sketch()

tests/test_workplanes.py

@@ -250,3 +250,52 @@ class TestWorkplanes(BaseTest):
             (bbBox.xlen, bbBox.ylen, bbBox.zlen), (1.0, 1.0, 1.0), 4
         )
         self.assertAlmostEqual(r.findSolid().Volume(), 1.0, 5)
+
+    def test_bezier_curve(self):
+        # Quadratic bezier
+        r = (
+            Workplane("XZ")
+            .bezier([(0, 0), (1, 2), (5, 0)])
+            .bezier([(1, -2), (0, 0)], includeCurrent=True)
+            .close()
+            .extrude(1)
+        )
+
+        bbBox = r.findSolid().BoundingBox()
+        # Why is the bounding box larger than expected?
+        self.assertTupleAlmostEquals((bbBox.xlen, bbBox.ylen, bbBox.zlen), (5, 1, 2), 1)
+        self.assertAlmostEqual(r.findSolid().Volume(), 6.6666667, 4)
+
+        r = Workplane("XY").bezier([(0, 0), (1, 2), (2, -1), (5, 0)])
+        self.assertTrue(len(r.ctx.pendingEdges) == 1)
+        r = (
+            r.lineTo(5, -0.1)
+            .bezier([(2, -3), (1, 0), (0, 0)], includeCurrent=True)
+            .close()
+            .extrude(1)
+        )
+
+        bbBox = r.findSolid().BoundingBox()
+        self.assertTupleAlmostEquals(
+            (bbBox.xlen, bbBox.ylen, bbBox.zlen), (5, 2.06767, 1), 1
+        )
+        self.assertAlmostEqual(r.findSolid().Volume(), 4.975, 4)
+
+        # Test makewire by translate and loft example like in
+        # the documentation
+        r = Workplane("XY").bezier([(0, 0), (1, 2), (1, -1), (0, 0)], makeWire=True)
+
+        self.assertTrue(len(r.ctx.pendingWires) == 1)
+        r = r.translate((0, 0, 0.2)).toPending().loft()
+        self.assertAlmostEqual(r.findSolid().Volume(), 0.09, 4)
+
+        # Finally test forConstruction
+        r = Workplane("XY").bezier(
+            [(0, 0), (1, 2), (1, -1), (0, 0)], makeWire=True, forConstruction=True
+        )
+        self.assertTrue(len(r.ctx.pendingWires) == 0)
+
+        r = Workplane("XY").bezier(
+            [(0, 0), (1, 2), (2, -1), (5, 0)], forConstruction=True
+        )
+        self.assertTrue(len(r.ctx.pendingEdges) == 0)