Sculpt: Topology automasking

The sculpt automasking feature assigns a factor to each vertex before starting the stroke. This can be used for isolating disconnected meshes, masking cavities, mesh boundary edges or creating topological falloffs.

This commit implements automasking in all brushes and topology automasking without topology falloff.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D5645

source/blender/makesrna/intern/rna_brush.c

@@ -1969,6 +1969,13 @@ static void rna_def_brush(BlenderRNA *brna)
                            "When locked keep using normal of surface where stroke was initiated");
   RNA_def_property_update(prop, 0, "rna_Brush_update");
 
+  prop = RNA_def_property(srna, "use_automasking_topology", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "automasking_flags", BRUSH_AUTOMASKING_TOPOLOGY);
+  RNA_def_property_ui_text(prop,
+                           "Topology Automasking",
+                           "Affect only vertices connected to the active vertex under the brush");
+  RNA_def_property_update(prop, 0, "rna_Brush_update");
+
   prop = RNA_def_property(srna, "use_scene_spacing", PROP_ENUM, PROP_NONE);
   RNA_def_property_enum_bitflag_sdna(prop, NULL, "flag");
   RNA_def_property_enum_items(prop, brush_spacing_unit_items);