Fix T85051: Add bisect distance as a parameter to the mirror modifier

The `bisect_distance` in the mirror modifier was hard-coded to `0.001`.
This would result in some unexpected behavior like vertices close
to the mirror plane being deleted or merged.

The fix now adds a parameter to the mirror modifier to expose the
bisect distance to the user. The default is set to the previous
hard-coded value to not "change" previous files.

Ref D10201

1 files changed, 8 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_modifier.c b/source/blender/makesrna/intern/rna_modifier.c
index 67335b81a31..e3fb443951f 100644
--- a/source/blender/makesrna/intern/rna_modifier.c
+++ b/source/blender/makesrna/intern/rna_modifier.c
@@ -2226,6 +2226,14 @@ static void rna_def_modifier_mirror(BlenderRNA *brna)
       prop, "Merge Distance", "Distance within which mirrored vertices are merged");
   RNA_def_property_update(prop, 0, "rna_Modifier_update");
 
+  prop = RNA_def_property(srna, "bisect_threshold", PROP_FLOAT, PROP_DISTANCE);
+  RNA_def_property_float_sdna(prop, NULL, "bisect_threshold");
+  RNA_def_property_range(prop, 0, FLT_MAX);
+  RNA_def_property_ui_range(prop, 0, 1, 0.01, 6);
+  RNA_def_property_ui_text(
+      prop, "Bisect Distance", "Distance from the bisect plane within which vertices are removed");
+  RNA_def_property_update(prop, 0, "rna_Modifier_update");
+
   prop = RNA_def_property(srna, "mirror_object", PROP_POINTER, PROP_NONE);
   RNA_def_property_pointer_sdna(prop, NULL, "mirror_ob");
   RNA_def_property_ui_text(prop, "Mirror Object", "Object to use as mirror");