Merge pull request #4810 from nortikin/curvature_colors

Viewer Draw Curve: indicate curvature by colors.

docs/nodes/viz/viewer_draw_curve.rst

@@ -76,7 +76,7 @@ The parameters of the node are (in this order):
 
 -------------
 
-* **Display Node Points**, **Node Points Color**, **Node Points Size**. Control
+* **Display Node Points** (N icon), **Node Points Color**, **Node Points Size**. Control
   display of curve's node points, for NURBS and NURBS-like curves. Nodes are
   not shown by default.
 
@@ -85,13 +85,22 @@ The parameters of the node are (in this order):
 
 -------------
 
-* **Display Curvature Comb**, **Comb Color**, **Comb Line Width**. Control
+* **Display Curvature Comb** (C icon), **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.
 
+-------------
+
+* **Indicate Curvature** (G icon), **Curvature Color**. If enabled, curve's
+  curvature is indicated by drawing a curve with a color gradient: the color
+  specified in **Curve Line Color** parameter is used to draw the most flat
+  curve segments, and the color specified in the **Curvature Color** parameter
+  is used to draw the places where curve's curvature hast the greatest value.
+  Disabled by default.
+
 Operators
 ---------
 
@@ -116,6 +125,11 @@ 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
 
+Example of curvature indication by color gradient:
+
+.. image:: https://user-images.githubusercontent.com/284644/206875486-4f018e3e-4b90-4b6d-9df1-28df129e65d2.png
+  :target: https://user-images.githubusercontent.com/284644/206875486-4f018e3e-4b90-4b6d-9df1-28df129e65d2.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>`

nodes/viz/viewer_draw_curve.py

@@ -22,11 +22,21 @@
 from sverchok.utils.sv_operator_mixins import SvGenericNodeLocator
 from sverchok.ui.bgl_callback_3dview import callback_disable, callback_enable
 
-def draw_edges(shader, points, edges, line_width, color):
+def draw_edges(shader, points, edges, line_width, color, is_smooth=False):
+    if is_smooth:
+        draw_edges_colored(shader, points, edges, line_width, [color for i in range(len(points))])
+    else:
+        bgl.glLineWidth(line_width)
+        batch = batch_for_shader(shader, 'LINES', {"pos": points}, indices=edges)
+        shader.bind()
+        shader.uniform_float('color', color)
+        batch.draw(shader)
+        bgl.glLineWidth(1)
+
+def draw_edges_colored(shader, points, edges, line_width, colors):
     bgl.glLineWidth(line_width)
-    batch = batch_for_shader(shader, 'LINES', {"pos": points}, indices=edges)
+    batch = batch_for_shader(shader, 'LINES', {"pos": points, "color": colors}, indices=edges)
     shader.bind()
-    shader.uniform_float('color', color)
     batch.draw(shader)
     bgl.glLineWidth(1)
 
@@ -38,18 +48,30 @@ def draw_points(shader, points, size, color):
     batch.draw(shader)
     bgl.glPointSize(1)
 
+def draw_points_colored(shader, points, size, colors):
+    bgl.glPointSize(size)
+    batch = batch_for_shader(shader, 'POINTS', {"pos": points, "color": colors})
+    shader.bind()
+    batch.draw(shader)
+    bgl.glPointSize(1)
+
 def draw_curves(context, args):
     node, draw_inputs, v_shader, e_shader = args
+    is_smooth = node.draw_curvature
 
     bgl.glEnable(bgl.GL_BLEND)
 
     for item in draw_inputs:
 
         if node.draw_line:
-            draw_edges(e_shader, item.points, item.edges, node.line_width, node.line_color)
+            if node.draw_curvature and item.curvature_point_colors is not None:
+                colors = item.curvature_point_colors.tolist()
+                draw_edges_colored(e_shader, item.points, item.edges, node.line_width, colors)
+            else:
+                draw_edges(e_shader, item.points, item.edges, node.line_width, node.line_color, is_smooth)
 
         if node.draw_control_polygon and item.control_points is not None:
-            draw_edges(e_shader, item.control_points, item.control_polygon_edges, node.control_polygon_line_width, node.control_polygon_color)
+            draw_edges(e_shader, item.control_points, item.control_polygon_edges, node.control_polygon_line_width, node.control_polygon_color, is_smooth)
 
         if node.draw_control_points and item.control_points is not None:
             draw_points(v_shader, item.control_points, node.control_points_size, node.control_points_color)
@@ -58,10 +80,13 @@ def draw_curves(context, args):
             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)
+            draw_edges(e_shader, item.comb_points, item.comb_edges, node.comb_width, node.comb_color, is_smooth)
 
         if node.draw_verts:
-            draw_points(v_shader, item.points, node.verts_size, node.verts_color)
+            if node.draw_curvature:
+                draw_points_colored(v_shader, item.points, node.verts_size, item.curvature_point_colors)
+            else:
+                draw_points(v_shader, item.points, node.verts_size, node.verts_color)
 
     bgl.glEnable(bgl.GL_BLEND)
 
@@ -193,6 +218,16 @@ class SvCurveViewerDrawNode(SverchCustomTreeNode, bpy.types.Node):
             min = 0.0, default = 1.0,
             update = updateNode)
 
+    draw_curvature: BoolProperty(
+        update=updateNode, name='Indicate Curvature', default=False)
+
+    curvature_color : FloatVectorProperty(
+            name = "Curvature Color",
+            default = (1.0, 0.1, 0.1, 1.0),
+            size = 4, min = 0.0, max = 1.0,
+            subtype = 'COLOR',
+            update = updateNode)
+
     def draw_buttons(self, context, layout):
         layout.prop(self, "activate", icon="HIDE_" + ("OFF" if self.activate else "ON"))
 
@@ -231,6 +266,10 @@ def draw_buttons(self, context, layout):
         if self.draw_comb:
             grid.prop(self, 'comb_scale', text='Scale')
 
+        row = grid.row(align=True)
+        row.prop(self, 'draw_curvature', text="", icon='EVENT_G')
+        row.prop(self, 'curvature_color', text="")
+
         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")
@@ -244,7 +283,10 @@ def sv_init(self, context):
     def draw_all(self, draw_inputs):
 
         v_shader = gpu.shader.from_builtin('3D_UNIFORM_COLOR')
-        e_shader = gpu.shader.from_builtin('3D_UNIFORM_COLOR')
+        if self.draw_curvature:
+            e_shader = gpu.shader.from_builtin('3D_SMOOTH_COLOR')
+        else:
+            e_shader = gpu.shader.from_builtin('3D_UNIFORM_COLOR')
 
         draw_data = {
                 'tree_name': self.id_data.name[:],

utils/curve/bakery.py

@@ -30,7 +30,7 @@ def __init__(self, node, curve, resolution):
         self.curve = curve
         self.resolution = resolution
 
-        if node.draw_line or node.draw_verts or node.draw_comb:
+        if node.draw_line or node.draw_verts or node.draw_comb or node.draw_curvature:
             t_min, t_max = curve.get_u_bounds()
             ts = np.linspace(t_min, t_max, num=resolution)
             n = len(ts)
@@ -53,10 +53,15 @@ def __init__(self, node, curve, resolution):
         else:
             self.node_points = None
 
+        if node.draw_comb or node.draw_curvature:
+            self.curvatures = curve.curvature_array(ts)
+        else:
+            self.curvatures = 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
+            curvatures = self.curvatures[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()
@@ -67,6 +72,20 @@ def __init__(self, node, curve, resolution):
             self.comb_points = None
             self.comb_edges = None
 
+        if node.draw_curvature:
+            color1 = np.array(node.line_color)
+            color2 = np.array(node.curvature_color)
+            #curvatures = np.tanh(self.curvatures)
+            curvatures = self.curvatures
+            c, C = curvatures.min(), curvatures.max()
+            coefs = (curvatures - c) / (C - c)
+            coefs = coefs[np.newaxis].T
+            self.curvature_point_colors = (1 - coefs) * color1 + coefs * color2
+            self.curvature_edge_colors = 0.5 * (self.curvature_point_colors[1:] + self.curvature_point_colors[:-1])
+        else:
+            self.curvature_point_colors = None
+            self.curvature_edge_colors = None
+
     def bake(self, object_name):
         me = bpy.data.meshes.new(object_name)
         me.from_pydata(self.points, self.edges, [])

utils/surface/bakery.py

@@ -97,6 +97,7 @@ def __init__(self):
             self.draw_control_points = False
             self.draw_nodes = False
             self.draw_comb = False
+            self.draw_curvature = False
 
     def __init__(self, node, surface, resolution_u, resolution_v):
         self.node = node