Copy Scale: support raising the copied scale to an arbitrary power.

Since scale is multiplicative, the appropriate way to partially copy
it is to use power. However, the influence slider of constraints uses
linear interpolation. Thus, there is no way to correctly split scale
via constraints without adding this feature.

In addition, this allows inverting scale by using negative powers,
fulfilling the function of Copy Rotation's Invert checkboxes.

1 files changed, 7 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_constraint.c b/source/blender/makesrna/intern/rna_constraint.c
index ef3ea19fa57..41ad94f6119 100644
--- a/source/blender/makesrna/intern/rna_constraint.c
+++ b/source/blender/makesrna/intern/rna_constraint.c
@@ -1327,6 +1327,13 @@ static void rna_def_constraint_size_like(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Copy Z", "Copy the target's Z scale");
   RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
 
+  prop = RNA_def_property(srna, "power", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_float_sdna(prop, NULL, "power");
+  RNA_def_property_float_default(prop, 1.0f);
+  RNA_def_property_ui_range(prop, -FLT_MAX, FLT_MAX, 1, 3);
+  RNA_def_property_ui_text(prop, "Power", "Raise the target's scale to the specified power");
+  RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+
   prop = RNA_def_property(srna, "use_offset", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "flag", SIZELIKE_OFFSET);
   RNA_def_property_ui_text(prop, "Offset", "Combine original scale with copied scale");