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

1 files changed, 7 insertions, 0 deletions

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,