Freestyle: Use of the Fill Range by Selection operator in the mesh edit mode.

This revision extends the functionality of the "Fill Range by Selection" button in
the "Distance from Camera/Object" modifiers so that only selected mesh vertices
in the edit mode are taken into account  (instead of considering all vertices when
in the object mode) to compute the min & max distances from the reference.
This will give users much finer control on the range values.

release/scripts/startup/bl_operators/freestyle.py

@@ -75,6 +75,32 @@ class SCENE_OT_freestyle_fill_range_by_selection(bpy.types.Operator):
         else:
             self.report({'ERROR'}, "Unexpected modifier type: " + m.type)
             return {'CANCELLED'}
+        # Find selected vertices in editmesh
+        ob = bpy.context.active_object
+        if ob.type == 'MESH' and ob.mode == 'EDIT' and ob.name != ref.name:
+            bpy.ops.object.mode_set(mode='OBJECT')
+            selected_verts = [v for v in bpy.context.active_object.data.vertices if v.select]
+            bpy.ops.object.mode_set(mode='EDIT')
+            # Compute the min/max distance from the reference to mesh vertices
+            min_dist = sys.float_info.max
+            max_dist = -min_dist
+            if m.type == 'DISTANCE_FROM_CAMERA':
+                ob_to_cam = matrix_to_camera * ob.matrix_world
+                for vert in selected_verts:
+                    # dist in the camera space
+                    dist = (ob_to_cam * vert.co).length
+                    min_dist = min(dist, min_dist)
+                    max_dist = max(dist, max_dist)
+            elif m.type == 'DISTANCE_FROM_OBJECT':
+                for vert in selected_verts:
+                    # dist in the world space
+                    dist = (ob.matrix_world * vert.co - target_location).length
+                    min_dist = min(dist, min_dist)
+                    max_dist = max(dist, max_dist)
+            # Fill the Range Min/Max entries with the computed distances
+            m.range_min = min_dist
+            m.range_max = max_dist
+            return {'FINISHED'}
         # Find selected mesh objects
         selection = [ob for ob in scene.objects if ob.select and ob.type == 'MESH' and ob.name != ref.name]
         if selection: