Geometry Nodes: Copy parameters when copying a curves data-block

Previously, things like materials, symmetry, and selection options
stored on `Curves` weren't copied to the result in nodes like the
subdivide and resample nodes. Now they are, which fixes some
unexpected behavior and allows visualization of the sculpt mode
selection.

In the realize instances and join nodes the behavior is the same as
for meshes, the parameters are taken from the first (top) input.

I also refactored some functions to return a `CurvesGeometry` by-value,
which makes it the responsibility of the node to copy the parameters.
That should make the algorithms more reusable in other situations.

Differential Revision: https://developer.blender.org/D15408

4 files changed, 42 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_curves.hh b/source/blender/blenkernel/BKE_curves.hh
index fb97e52f6da..25a912b8825 100644
--- a/source/blender/blenkernel/BKE_curves.hh
+++ b/source/blender/blenkernel/BKE_curves.hh
@@ -735,6 +735,12 @@ Curves *curves_new_nomain(CurvesGeometry curves);
  */
 Curves *curves_new_nomain_single(int points_num, CurveType type);
 
+/**
+ * Copy data from #src to #dst, except the geometry data in #CurvesGeometry. Typically used to
+ * copy high-level parameters when a geometry-altering operation creates a new curves data-block.
+ */
+void curves_copy_parameters(const Curves &src, Curves &dst);
+
 std::array<int, CURVE_TYPES_NUM> calculate_type_counts(const VArray<int8_t> &types);
 
 /* -------------------------------------------------------------------- */
diff --git a/source/blender/blenkernel/BKE_curves_utils.hh b/source/blender/blenkernel/BKE_curves_utils.hh
index f223e173ea9..0fbd33002e1 100644
--- a/source/blender/blenkernel/BKE_curves_utils.hh
+++ b/source/blender/blenkernel/BKE_curves_utils.hh
@@ -56,6 +56,13 @@ void fill_points(const CurvesGeometry &curves,
 }
 
 /**
+ * Copy only the information on the point domain, but not the offsets or any point attributes,
+ * meant for operations that change the number of points but not the number of curves.
+ * \warning The returned curves have invalid offsets!
+ */
+bke::CurvesGeometry copy_only_curve_domain(const bke::CurvesGeometry &src_curves);
+
+/**
  * Copy the size of every curve in #curve_ranges to the corresponding index in #counts.
  */
 void fill_curve_counts(const bke::CurvesGeometry &curves,
diff --git a/source/blender/blenkernel/intern/curves.cc b/source/blender/blenkernel/intern/curves.cc
index 78791b55b4d..7e9f994313b 100644
--- a/source/blender/blenkernel/intern/curves.cc
+++ b/source/blender/blenkernel/intern/curves.cc
@@ -388,6 +388,23 @@ Curves *curves_new_nomain(CurvesGeometry curves)
   return curves_id;
 }
 
+void curves_copy_parameters(const Curves &src, Curves &dst)
+{
+  dst.flag = src.flag;
+  dst.attributes_active_index = src.attributes_active_index;
+  MEM_SAFE_FREE(dst.mat);
+  dst.mat = static_cast<Material **>(MEM_malloc_arrayN(src.totcol, sizeof(Material *), __func__));
+  dst.totcol = src.totcol;
+  MutableSpan(dst.mat, dst.totcol).copy_from(Span(src.mat, src.totcol));
+  dst.symmetry = src.symmetry;
+  dst.selection_domain = src.selection_domain;
+  dst.surface = src.surface;
+  MEM_SAFE_FREE(dst.surface_uv_map);
+  if (src.surface_uv_map != nullptr) {
+    dst.surface_uv_map = BLI_strdup(src.surface_uv_map);
+  }
+}
+
 CurvesSurfaceTransforms::CurvesSurfaceTransforms(const Object &curves_ob, const Object *surface_ob)
 {
   this->curves_to_world = curves_ob.obmat;
diff --git a/source/blender/blenkernel/intern/curves_utils.cc b/source/blender/blenkernel/intern/curves_utils.cc
index f7db60ee588..d98832e796c 100644
--- a/source/blender/blenkernel/intern/curves_utils.cc
+++ b/source/blender/blenkernel/intern/curves_utils.cc
@@ -84,6 +84,18 @@ void fill_points(const CurvesGeometry &curves,
   });
 }
 
+bke::CurvesGeometry copy_only_curve_domain(const bke::CurvesGeometry &src_curves)
+{
+  bke::CurvesGeometry dst_curves(0, src_curves.curves_num());
+  CustomData_copy(&src_curves.curve_data,
+                  &dst_curves.curve_data,
+                  CD_MASK_ALL,
+                  CD_DUPLICATE,
+                  src_curves.curves_num());
+  dst_curves.runtime->type_counts = src_curves.runtime->type_counts;
+  return dst_curves;
+}
+
 IndexMask indices_for_type(const VArray<int8_t> &types,
                            const std::array<int, CURVE_TYPES_NUM> &type_counts,
                            const CurveType type,