"Fillet curve" node

docs/nodes/curve/fillet_curve.rst

@@ -0,0 +1,123 @@
+Fillet Curve
+============
+
+Functionality
+-------------
+
+This node takes a NURBS (or NURBS-like) Curve object, finds it's "fracture"
+points (i.e. points where tangent of the curve does not change continuously),
+and makes a smooth fillet in such points.
+
+For polyline curves, it is possible to make a fillet made of circular arc, and
+it is possible to make the arc of user-provided radius.
+For other types of curves, it is not possible to automatically calculate
+circular fillet based on radius. So, for other types of curves, this node makes
+fillets by use of Bezier curves or biarcs. Points where original curve is glued
+with the fillet curve are in such case specified in terms of curve's T
+parameter space, instead of fillet radius.
+
+More specifically, what this node does is follows:
+
+* If it is known that the curve is a polyline: replace all corners of the
+  polyline with a circular arc of a specified radius.
+* For other types of NURBS curves,
+
+   * Find fracture points of the curve.
+   * Split the curve into segments at these fracture points.
+   * Of each segment, cut a small (or not small) piece at each end, based on
+     **CutOffset** input and segment's T parameter span. For example, if
+     CutOffset is 0.05, and segment's T parameter span is 1.0 - 2.0, then this
+     will cut the segment at points 1.05 and 1.95, leaving only span of 1.05 -
+     1.95. So at this step, there will be gaps between segments.
+   * Place a fillet curve (Bezier curve or BiArc) at each gap.
+
+This node will automatically detect if the input curve is closed, and, if
+necessary, add a fillet at closing point.
+
+You can also want to take a look at **Blend Curves** node.
+
+Inputs
+------
+
+This node has the following inputs:
+
+* **Curve**. The curve to make fillets for. This input is mandatory.
+* **Radius**. This input is only available when **Polylines only** parameter is
+  checked. This specifies the fillet radius. It is possible to provide a
+  separate fillet radius for each vertex of the polyline curve. The default
+  value is 0.2.
+* **CutOffset**. This input is only available when **Polylines only** parameter
+  is not checked. This specifies the proportion of curve segment T parameter
+  span, which will be cut off of each segment in order to make a place for the
+  fillet curve. The default value is 0.05.
+* **BulgeFactor**. This input is only available when **Polylines only**
+  parameter is not checked, and **Continuity** parameter is set to **1 -
+  Tangency**. This defines the strength with which the tangent vector of the
+  second curve at it's starting point will affect the generated blending curve.
+  The default value is 0.5.
+
+Parameters
+----------
+
+This node has the following parameters:
+
+* **Polylines only**. If this is checked, the curve will process only
+  polylines. If you feed it with any other curve, the node will fail. In this
+  mode, it is possible to make fillets in form of circular arc, and provide the
+  fillet radius. If this is not checked, the node will process any NURBS or
+  NURBS-like curve, but it will not be able to make circular arc fillets based
+  on fillet radius.
+* **Continuity**. This defines the order of continuity of the resulting curve,
+  and the algorithm used to calculate the fillet curves. The available options are:
+
+   * **0 - Position**. This will connect curve segments with a straight line
+     segment. So, effectively, this does a bevel instead of smooth fillet.
+   * **1 - Tangency**. The fillet curves are generated so that the tangent of
+     the curves are equal at points where fillet curves are joined with
+     original curve segments. The generated fillet curves are cubic Bezier
+     curves.
+   * **1 - BiArc**. This option is not available when **Polylines only**
+     parameter is checked. The fillet curves are generated as biarc_ curves,
+     i.e.  pairs of circular arcs; they are generated so that the tanent
+     vectors of the segments are equal at their meeting points. Biarc parameter
+     will be set to 1.0. Note that this option works only when tangents of the
+     curve at points where it is replaced with fillet are coplanar. I.e., this
+     will work fine for planar curves, but may fail in other cases.
+   * **1 - Circular Arc**. This option is only available when **Polylines
+     only** parameter is not checked. Fillet curves are calculated as circular
+     arc of radiuses provided in the **Radius** input.
+
+   The default value is **0 - Position**.
+
+* **Concatenate**. If checked, then the node will output all segments of
+  initial curve together with generated fillet curves, concatenated into one
+  curve.  Otherwise, original curve segments and fillet curves will be output
+  as separate Curve objects. Checked by default.
+* **Even domains**. This parameter is available in the N panel only. If
+  checked, give each segment a domain of length 1. This parameter is only
+  available if **Concatenate** parameter is checked.  Unchecked by default.
+
+.. _biarc: https://en.wikipedia.org/wiki/Biarc
+
+Outputs
+-------
+
+This node has the following outputs:
+
+* **Curve**. Generated Curve objects.
+* **Centers**. This output is only available when **Polylines only** parameter
+  is checked, and **Continuity** parameter is set to **1 - Circular Arc**.
+  Centers of circles used to make fillet arcs. These are matrices, since this
+  output provides not only centers, but also orientation of the circles.
+
+Examples of Usage
+-----------------
+
+Make fillets on some curve:
+
+.. image:: https://user-images.githubusercontent.com/284644/205504044-bdaa43c8-f13f-4ff4-92f4-aca8100c989b.png
+
+Make circular arc fillets on a polyline:
+
+.. image:: https://user-images.githubusercontent.com/284644/205504045-aab871b9-c851-484c-a908-230cd463e060.png
+

index.yaml

@@ -86,6 +86,7 @@
         - SvExNurbsCurveNode
         - SvApproxNurbsCurveMk2Node
         - SvExInterpolateNurbsCurveNode
+        - SvFilletCurveNode
         - SvDeconstructCurveNode
         - SvNurbsCurveNodesNode
         - ---

nodes/curve/fillet_curve.py

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+# This file is part of project Sverchok. It's copyrighted by the contributors
+# recorded in the version control history of the file, available from
+# its original location https://github.com/nortikin/sverchok/commit/master
+#
+# SPDX-License-Identifier: GPL3
+# License-Filename: LICENSE
+
+import numpy as np
+
+import bpy
+from bpy.props import FloatProperty, EnumProperty, BoolProperty, IntProperty
+from mathutils import Vector
+
+from sverchok.node_tree import SverchCustomTreeNode
+from sverchok.data_structure import updateNode, zip_long_repeat, repeat_last_for_length, ensure_nesting_level, get_data_nesting_level
+from sverchok.utils.curve.core import SvCurve
+from sverchok.utils.curve.nurbs import SvNurbsCurve
+from sverchok.utils.curve.fillet import (
+        SMOOTH_POSITION, SMOOTH_TANGENT, SMOOTH_ARC, SMOOTH_BIARC, SMOOTH_QUAD, SMOOTH_NORMAL, SMOOTH_CURVATURE,
+        fillet_polyline_from_curve, fillet_nurbs_curve
+    )
+from sverchok.utils.handle_blender_data import keep_enum_reference
+
+class SvFilletCurveNode(SverchCustomTreeNode, bpy.types.Node):
+    """
+    Triggers: Fillet Curve Bevel
+    Tooltip: Smooth a NURBS curve (or polyline) by adding fillets or bevels in it's fracture points.
+    """
+    bl_idname = 'SvFilletCurveNode'
+    bl_label = 'Fillet Curve'
+    bl_icon = 'OUTLINER_OB_EMPTY'
+    sv_icon = 'SV_FILLET_POLYLINE'
+
+    radius : FloatProperty(
+        name = "Radius",
+        min = 0.0,
+        default = 0.2,
+        update = updateNode)
+
+    cut_offset : FloatProperty(
+        name = "Cut Offset",
+        default = 0.05,
+        min = 0.0,
+        update = updateNode)
+
+    bulge_factor : FloatProperty(
+        name = "Bulge Factor",
+        default = 0.5,
+        min = 0.0,
+        update = updateNode)
+
+    concat : BoolProperty(
+        name = "Concatenate",
+        default = True,
+        update = updateNode)
+
+    scale_to_unit : BoolProperty(
+        name = "Even domains",
+        description = "Give each segment and each arc equal T parameter domain of [0; 1]",
+        default = False,
+        update = updateNode)
+
+    @keep_enum_reference
+    def get_smooth_modes(self, context):
+        items = []
+        items.append((SMOOTH_POSITION, "0 - Position", "Connect segments with straight line segment", 0))
+        items.append((SMOOTH_TANGENT, "1 - Tangency", "Connect segments such that their tangents are smoothly joined", 1))
+        if not self.is_polyline:
+            items.append((SMOOTH_BIARC, "1 - Bi Arc", "Connect segments with Bi Arc, such that tangents are smoothly joined", 2))
+            #items.append((SMOOTH_NORMAL, "2 - Normals", "Connect segments such that their normals (second derivatives) are smoothly joined", 3))
+            #items.append((SMOOTH_CURVATURE, "3 - Curvature", "Connect segments such that their curvatures (third derivatives) are smoothly joined", 4))
+        else:
+            items.append((SMOOTH_ARC, "1 - Circular Arc", "Connect segments with circular arcs", 5))
+        return items
+
+    def update_sockets(self, context):
+        self.inputs['Radius'].hide_safe = not self.is_polyline
+        self.inputs['CutOffset'].hide_safe = self.is_polyline
+        self.inputs['BulgeFactor'].hide_safe = self.is_polyline or self.smooth_mode != SMOOTH_TANGENT
+        self.outputs['Centers'].hide_safe = not (self.is_polyline and self.smooth_mode == SMOOTH_ARC)
+        self.outputs['Radius'].hide_safe = not (self.is_polyline and self.smooth_mode == SMOOTH_ARC)
+        updateNode(self, context)
+
+    smooth_mode : EnumProperty(
+        name = "Continuity",
+        description = "How smooth should be the curve at points where original curve is replaced with fillet arcs; bigger value give more smooth touching",
+        items = get_smooth_modes,
+        update = update_sockets)
+
+    is_polyline : BoolProperty(
+        name = "Polylines only",
+        description = "If checked, the node will work with polylines only, but `Circular Arc' option will be available",
+        default = False,
+        update = update_sockets)
+
+    def draw_buttons(self, context, layout):
+        layout.prop(self, 'is_polyline')
+        layout.label(text="Continuity")
+        layout.prop(self, 'smooth_mode', text='')
+        layout.prop(self, "concat")
+
+    def draw_buttons_ext(self, context, layout):
+        self.draw_buttons(context, layout)
+        if self.concat:
+            layout.prop(self, "scale_to_unit")
+
+    def sv_init(self, context):
+        self.inputs.new('SvCurveSocket', "Curve")
+        self.inputs.new('SvStringsSocket', "Radius").prop_name = 'radius'
+        self.inputs.new('SvStringsSocket', "CutOffset").prop_name = 'cut_offset'
+        self.inputs.new('SvStringsSocket', "BulgeFactor").prop_name = 'bulge_factor'
+        self.outputs.new('SvCurveSocket', "Curve")
+        self.outputs.new('SvMatrixSocket', "Centers")
+        self.outputs.new('SvStringsSocket', "Radius")
+        self.update_sockets(context)
+
+    def process(self):
+        if not any(socket.is_linked for socket in self.outputs):
+            return
+
+        curves_s = self.inputs['Curve'].sv_get()
+        radius_s = self.inputs['Radius'].sv_get()
+        cut_offset_s = self.inputs['CutOffset'].sv_get()
+        bulge_factor_s = self.inputs['BulgeFactor'].sv_get()
+
+        input_level = get_data_nesting_level(curves_s, data_types=(SvCurve,))
+        nested_output = input_level > 1
+
+        curves_s = ensure_nesting_level(curves_s, 2, data_types=(SvCurve,))
+        if self.is_polyline:
+            radius_s = ensure_nesting_level(radius_s, 3)
+        else:
+            radius_s = ensure_nesting_level(radius_s, 2)
+        cut_offset_s = ensure_nesting_level(cut_offset_s, 2)
+        bulge_factor_s = ensure_nesting_level(bulge_factor_s, 2)
+
+        curves_out = []
+        centers_out = []
+        radius_out = []
+        for params in zip_long_repeat(curves_s, radius_s, cut_offset_s, bulge_factor_s):
+            new_curves = []
+            new_centers = []
+            new_radiuses = []
+            for curve, radiuses, cut_offset, bulge_factor in zip_long_repeat(*params):
+                curve = SvNurbsCurve.to_nurbs(curve)
+                if curve is None:
+                    raise Exception("One of curves is not a NURBS")
+                if self.is_polyline:
+                    curve, centers, radiuses = fillet_polyline_from_curve(curve, radiuses,
+                                smooth = self.smooth_mode,
+                                concat = self.concat,
+                                scale_to_unit = self.scale_to_unit)
+                    new_centers.append(centers)
+                    new_curves.append(curve)
+                    new_radiuses.append(radiuses)
+                else:
+                    curve = fillet_nurbs_curve(curve,
+                                smooth = self.smooth_mode,
+                                cut_offset = cut_offset,
+                                bulge_factor = bulge_factor)
+                    new_curves.append(curve)
+            if nested_output:
+                curves_out.append(new_curves)
+                centers_out.append(new_centers)
+                radius_out.append(new_radiuses)
+            else:
+                curves_out.extend(new_curves)
+                centers_out.extend(new_centers)
+                radius_out.extend(new_radiuses)
+
+        self.outputs['Curve'].sv_set(curves_out)
+        self.outputs['Centers'].sv_set(centers_out)
+        self.outputs['Radius'].sv_set(radius_out)
+
+def register():
+    bpy.utils.register_class(SvFilletCurveNode)
+
+def unregister():
+    bpy.utils.unregister_class(SvFilletCurveNode)
+