Viewer Draw Curve node: Curvature comb

docs/nodes/viz/viewer_draw_curve.rst

@@ -83,6 +83,15 @@ The parameters of the node are (in this order):
 .. image:: https://user-images.githubusercontent.com/14288520/190176111-16a43da1-2fd4-4b1c-bf74-78712bcd6a3f.png
   :target: https://user-images.githubusercontent.com/14288520/190176111-16a43da1-2fd4-4b1c-bf74-78712bcd6a3f.png
 
+-------------
+
+* **Display Curvature Comb**, **Comb Color**, **Comb Line Width**. Control
+  display of curve's curvature comb. Curvature comb is not shown by default.
+* **Scale**. This parameter is available only when **Display Curvature Comb**
+  parameter is enabled. This defines the scaling applied to curve normals used
+  to display the curvature comb. The default value of 1.0 means that normals
+  length will be equal to curve's curvature in corresponding points.
+
 Operators
 ---------
 
@@ -102,6 +111,11 @@ Example of Usage
 .. image:: https://user-images.githubusercontent.com/14288520/190133906-61748350-414f-4d3e-8e71-2bd6be30597c.png
   :target: https://user-images.githubusercontent.com/14288520/190133906-61748350-414f-4d3e-8e71-2bd6be30597c.png
 
+Example of curvature comb display:
+
+.. image:: https://user-images.githubusercontent.com/284644/206860681-a70d93af-a72b-4dcb-bf36-3678135b835a.png
+  :target: https://user-images.githubusercontent.com/284644/206860681-a70d93af-a72b-4dcb-bf36-3678135b835a.png
+
 * Generator-> :doc:`Line </nodes/generator/line_mk4>`
 * Transform-> :doc:`Randomize </nodes/transforms/randomize>`
-* Curves->NURBS-> :doc:`Approximate NURBS Curve </nodes/curve/approximate_nurbs_curve>`
+* Curves->NURBS-> :doc:`Approximate NURBS Curve </nodes/curve/approximate_nurbs_curve>`

nodes/viz/viewer_draw_curve.py

@@ -9,7 +9,7 @@
 
 import bpy
 from mathutils import Matrix, Vector
-from bpy.props import StringProperty, BoolProperty, IntProperty, EnumProperty, FloatVectorProperty
+from bpy.props import StringProperty, BoolProperty, IntProperty, EnumProperty, FloatVectorProperty, FloatProperty
 import bgl
 import gpu
 from gpu_extras.batch import batch_for_shader
@@ -57,6 +57,9 @@ def draw_curves(context, args):
         if node.draw_nodes and item.node_points is not None:
             draw_points(v_shader, item.node_points, node.nodes_size, node.nodes_color)
 
+        if node.draw_comb and item.comb_edges is not None:
+            draw_edges(e_shader, item.comb_points, item.comb_edges, node.comb_width, node.comb_color)
+
         if node.draw_verts:
             draw_points(v_shader, item.points, node.verts_size, node.verts_color)
 
@@ -170,6 +173,26 @@ class SvCurveViewerDrawNode(SverchCustomTreeNode, bpy.types.Node):
             min = 1, default = 3,
             update = updateNode)
 
+    draw_comb: BoolProperty(
+        update=updateNode, name='Display curvature comb', default=False)
+
+    comb_color: FloatVectorProperty(
+            name = "Comb Color",
+            default = (1.0, 0.9, 0.1, 0.5),
+            size = 4, min = 0.0, max = 1.0,
+            subtype = 'COLOR',
+            update = updateNode)
+
+    comb_width : IntProperty(
+            name = "Comb Line Width",
+            min = 1, default = 1,
+            update = updateNode)
+
+    comb_scale : FloatProperty(
+            name = "Comb Scale",
+            min = 0.0, default = 1.0,
+            update = updateNode)
+
     def draw_buttons(self, context, layout):
         layout.prop(self, "activate", icon="HIDE_" + ("OFF" if self.activate else "ON"))
 
@@ -200,6 +223,14 @@ def draw_buttons(self, context, layout):
         row.prop(self, 'nodes_color', text="")
         row.prop(self, 'nodes_size', text="px")
 
+        row = grid.row(align=True)
+        row.prop(self, 'draw_comb', text="", icon='EVENT_C')
+        row.prop(self, 'comb_color', text="")
+        row.prop(self, 'comb_width', text="px")
+
+        if self.draw_comb:
+            grid.prop(self, 'comb_scale', text='Scale')
+
         row = layout.row(align=True)
         row.scale_y = 4.0 if self.prefs_over_sized_buttons else 1
         self.wrapper_tracked_ui_draw_op(row, SvBakeCurveOp.bl_idname, icon='OUTLINER_OB_MESH', text="B A K E")

utils/curve/bakery.py

@@ -30,13 +30,13 @@ def __init__(self, node, curve, resolution):
         self.curve = curve
         self.resolution = resolution
 
-        if node.draw_line or node.draw_verts:
+        if node.draw_line or node.draw_verts or node.draw_comb:
             t_min, t_max = curve.get_u_bounds()
             ts = np.linspace(t_min, t_max, num=resolution)
+            n = len(ts)
             self.points = curve.evaluate_array(ts).tolist()
 
         if node.draw_line:
-            n = len(ts)
             self.edges = [(i,i+1) for i in range(n-1)]
 
         if (node.draw_control_polygon or node.draw_control_points) and hasattr(curve, 'get_control_points'):
@@ -53,6 +53,20 @@ def __init__(self, node, curve, resolution):
         else:
             self.node_points = None
 
+        if node.draw_comb:
+            n = len(self.points)
+            normals = curve.main_normal_array(ts, normalize=True)
+            curvatures = curve.curvature_array(ts)[np.newaxis].T
+            comb_normals = node.comb_scale * curvatures * normals
+            comb_points = self.points - comb_normals
+            self.comb_points = np.concatenate((self.points, comb_points)).tolist()
+            comb_normal_edges = [(i, i+n) for i in range(n-1)]
+            comb_tangent_edges = [(i, i+1) for i in range(n, 2*n-1)]
+            self.comb_edges = comb_normal_edges + comb_tangent_edges
+        else:
+            self.comb_points = None
+            self.comb_edges = None
+
     def bake(self, object_name):
         me = bpy.data.meshes.new(object_name)
         me.from_pydata(self.points, self.edges, [])

utils/surface/bakery.py

@@ -96,6 +96,7 @@ def __init__(self):
             self.draw_control_polygon = False
             self.draw_control_points = False
             self.draw_nodes = False
+            self.draw_comb = False
 
     def __init__(self, node, surface, resolution_u, resolution_v):
         self.node = node