Inset Special node: possibility to work with inset = zero.

This adds a new parameter - "Zero inset faces". It defines what to do with faces when inset is set to zero. Old behaivour (skip such faces as if they were masked out) is defined by "Skip" mode. In "Fan" mode, such faces are processed as usual - the internal face just becomes degenerated and so is merged into single vertex, so we have a fan-like stucture.

Inset Special node: possibility to work with inset = zero.
This adds a new parameter - "Zero inset faces". It defines what to do with faces when inset is set to zero. Old behaivour (skip such faces as if they were masked out) is defined by "Skip" mode. In "Fan" mode, such faces are processed as usual - the internal face just becomes degenerated and so is merged into single vertex, so we have a fan-like stucture.
752c0617 · Ilya Portnov · e7fba561 · 752c0617
--- a/nodes/CAD/inset_special.py
+++ b/nodes/CAD/inset_special.py
@@ -34,7 +34,7 @@ from sverchok.data_structure import (
 ''' very non optimal routines. beware. I know this '''
-def inset_special(vertices, faces, inset_rates, distances, ignores, make_inners, normal_mode="Fast"):
+def inset_special(vertices, faces, inset_rates, distances, ignores, make_inners, normal_mode="Exact", zero_mode="SKIP"):
    new_faces = []
    new_ignores = []
@@ -112,6 +112,17 @@ def inset_special(vertices, faces, inset_rates, distances, ignores, make_inners,
        verts = [vertices[i] for i in face]
        avg_vec = get_average_vector(verts, n)
+        if abs(inset_by) < 1e-6:
+            normal = calc_normal(verts)
+            new_vertex = avg_vec.lerp(avg_vec + normal, distance)
+            vertices.append(new_vertex)
+            new_vertex_idx = current_verts_idx
+            new_faces
+            for i, j in zip(face, face[1:]):
+                new_faces.append([i, j, new_vertex_idx])
+            new_faces.append([face[-1], face[0], new_vertex_idx])
+            return
        # lerp and add to vertices immediately
        new_verts_prime = [avg_vec.lerp(v, inset_by) for v in verts]
@@ -133,7 +144,8 @@ def inset_special(vertices, faces, inset_rates, distances, ignores, make_inners,
    for idx, face in enumerate(faces):
        inset_by = inset_rates[idx]
-        if (inset_by > 0) and (not ignores[idx]):
+        good_inset = (inset_by > 0) or (zero_mode == 'FAN')
+        if good_inset and (not ignores[idx]):
            new_inner_from(face, inset_by, distances[idx], make_inners[idx])
        else:
            new_faces.append(face)
@@ -162,6 +174,7 @@ class SvInsetSpecial(bpy.types.Node, SverchCustomTreeNode):
    inset : FloatProperty(
        name='Inset',
        description='inset amount',
+        min = 0.0,
        default=0.1, update=updateNode)
    distance: FloatProperty(
        name='Distance',
@@ -173,10 +186,21 @@ class SvInsetSpecial(bpy.types.Node, SverchCustomTreeNode):
    normal_mode : EnumProperty(name = "Normals",
            description = "Normals calculation algorithm",
-            default = "Fast",
+            default = "Exact",
            items = normal_modes,
            update = updateNode)
+    zero_modes = [
+            ("SKIP", "Skip", "Do not process such faces", 0),
+            ("FAN", "Fan", "Make a fan-like structure from such faces", 1)
+        ]
+    zero_mode : EnumProperty(name = "Zero inset faces",
+            description = "What to do with faces when inset is equal to zero",
+            default = "SKIP",
+            items = zero_modes,
+            update = updateNode)
    # axis = FloatVectorProperty(
    #   name='axis', description='axis relative to normal',
    #   default=(0,0,1), update=updateNode)
@@ -198,6 +222,7 @@ class SvInsetSpecial(bpy.types.Node, SverchCustomTreeNode):
    def draw_buttons_ext(self, context, layout):
        layout.prop(self, "normal_mode")
+        layout.prop(self, "zero_mode")
    def process(self):
        i = self.inputs
@@ -240,7 +265,8 @@ class SvInsetSpecial(bpy.types.Node, SverchCustomTreeNode):
                'distances': distance_vals,
                'make_inners': make_inners,
                'ignores': ignores,
-                'normal_mode': self.normal_mode
+                'normal_mode': self.normal_mode,
+                'zero_mode': self.zero_mode
            }
            res = inset_special(**func_args)