Curves: correctly initialize new attributes

Previously, the new attributes were zero-initialized. However, sometimes
the default has to be something else. The old behavior led to unexpected
behavior in the Snap Curves to Surface operator in Deform mode, when the
curves were not attached to the surface before.

Differential Revision: https://developer.blender.org/D14588

1 files changed, 14 insertions, 9 deletions

diff --git a/source/blender/blenkernel/intern/curves_geometry.cc b/source/blender/blenkernel/intern/curves_geometry.cc
index 7d89892f69b..dff56bd2b97 100644
--- a/source/blender/blenkernel/intern/curves_geometry.cc
+++ b/source/blender/blenkernel/intern/curves_geometry.cc
@@ -202,7 +202,8 @@ static Span<T> get_span_attribute(const CurvesGeometry &curves,
 template<typename T>
 static MutableSpan<T> get_mutable_attribute(CurvesGeometry &curves,
                                             const AttributeDomain domain,
-                                            const StringRefNull name)
+                                            const StringRefNull name,
+                                            const T default_value = T())
 {
   const int size = domain_size(curves, domain);
   const CustomDataType type = cpp_type_to_custom_data_type(CPPType::get<T>());
@@ -215,7 +216,11 @@ static MutableSpan<T> get_mutable_attribute(CurvesGeometry &curves,
   }
   data = (T *)CustomData_add_layer_named(
       &custom_data, type, CD_CALLOC, nullptr, size, name.c_str());
-  return {data, size};
+  MutableSpan<T> span = {data, size};
+  if (span.first() != default_value) {
+    span.fill(default_value);
+  }
+  return span;
 }
 
 VArray<int8_t> CurvesGeometry::curve_types() const
@@ -303,7 +308,7 @@ VArray<bool> CurvesGeometry::cyclic() const
 }
 MutableSpan<bool> CurvesGeometry::cyclic_for_write()
 {
-  return get_mutable_attribute<bool>(*this, ATTR_DOMAIN_CURVE, ATTR_CYCLIC);
+  return get_mutable_attribute<bool>(*this, ATTR_DOMAIN_CURVE, ATTR_CYCLIC, false);
 }
 
 VArray<int> CurvesGeometry::resolution() const
@@ -312,7 +317,7 @@ VArray<int> CurvesGeometry::resolution() const
 }
 MutableSpan<int> CurvesGeometry::resolution_for_write()
 {
-  return get_mutable_attribute<int>(*this, ATTR_DOMAIN_CURVE, ATTR_RESOLUTION);
+  return get_mutable_attribute<int>(*this, ATTR_DOMAIN_CURVE, ATTR_RESOLUTION, 12);
 }
 
 VArray<int8_t> CurvesGeometry::handle_types_left() const
@@ -321,7 +326,7 @@ VArray<int8_t> CurvesGeometry::handle_types_left() const
 }
 MutableSpan<int8_t> CurvesGeometry::handle_types_left_for_write()
 {
-  return get_mutable_attribute<int8_t>(*this, ATTR_DOMAIN_POINT, ATTR_HANDLE_TYPE_LEFT);
+  return get_mutable_attribute<int8_t>(*this, ATTR_DOMAIN_POINT, ATTR_HANDLE_TYPE_LEFT, 0);
 }
 
 VArray<int8_t> CurvesGeometry::handle_types_right() const
@@ -330,7 +335,7 @@ VArray<int8_t> CurvesGeometry::handle_types_right() const
 }
 MutableSpan<int8_t> CurvesGeometry::handle_types_right_for_write()
 {
-  return get_mutable_attribute<int8_t>(*this, ATTR_DOMAIN_POINT, ATTR_HANDLE_TYPE_RIGHT);
+  return get_mutable_attribute<int8_t>(*this, ATTR_DOMAIN_POINT, ATTR_HANDLE_TYPE_RIGHT, 0);
 }
 
 Span<float3> CurvesGeometry::handle_positions_left() const
@@ -357,7 +362,7 @@ VArray<int8_t> CurvesGeometry::nurbs_orders() const
 }
 MutableSpan<int8_t> CurvesGeometry::nurbs_orders_for_write()
 {
-  return get_mutable_attribute<int8_t>(*this, ATTR_DOMAIN_CURVE, ATTR_NURBS_ORDER);
+  return get_mutable_attribute<int8_t>(*this, ATTR_DOMAIN_CURVE, ATTR_NURBS_ORDER, 4);
 }
 
 Span<float> CurvesGeometry::nurbs_weights() const
@@ -375,7 +380,7 @@ VArray<int8_t> CurvesGeometry::nurbs_knots_modes() const
 }
 MutableSpan<int8_t> CurvesGeometry::nurbs_knots_modes_for_write()
 {
-  return get_mutable_attribute<int8_t>(*this, ATTR_DOMAIN_CURVE, ATTR_NURBS_KNOTS_MODE);
+  return get_mutable_attribute<int8_t>(*this, ATTR_DOMAIN_CURVE, ATTR_NURBS_KNOTS_MODE, 0);
 }
 
 VArray<int> CurvesGeometry::surface_triangle_indices() const
@@ -385,7 +390,7 @@ VArray<int> CurvesGeometry::surface_triangle_indices() const
 
 MutableSpan<int> CurvesGeometry::surface_triangle_indices_for_write()
 {
-  return get_mutable_attribute<int>(*this, ATTR_DOMAIN_CURVE, ATTR_SURFACE_TRIANGLE_INDEX);
+  return get_mutable_attribute<int>(*this, ATTR_DOMAIN_CURVE, ATTR_SURFACE_TRIANGLE_INDEX, -1);
 }
 
 Span<float2> CurvesGeometry::surface_triangle_coords() const