Curves: Changes to the new curves data-block

This patch refactors the "Hair" data-block, which will soon be renamed
to "Curves". The larger change is switching from an array of `HairCurve`
to find indices in the points array to simply storing an array of offsets.
Using a single integer instead of two halves the amount of memory for that
particular array.

Besides that, there are some other changes in this patch:
- Split the data-structure to a separate `CurveGeometry`
  DNA struct so it is usable for grease pencil too.
- Update naming to be more aligned with newer code and the style guide.
- Add direct access to some arrays in RNA
-- Radius is now retrieved as a regular attribute in Cycles.
-- `HairPoint` has been renamed to `CurvePoint`
-- `HairCurve` has been renamed to `CurveSlice`
- Add comments to the struct in DNA.

The next steps are renaming `Hair` -> `Curves`, and adding support
for other curve types: Bezier, Poly, and NURBS.

Ref T95355

Differential Revision: https://developer.blender.org/D13987

1 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/blenloader/intern/versioning_290.c b/source/blender/blenloader/intern/versioning_290.c
index 888bd244007..ef146606ff0 100644
--- a/source/blender/blenloader/intern/versioning_290.c
+++ b/source/blender/blenloader/intern/versioning_290.c
@@ -1122,7 +1122,7 @@ void blo_do_versions_290(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     /* Hair and PointCloud attributes. */
     for (Hair *hair = bmain->hairs.first; hair != NULL; hair = hair->id.next) {
-      do_versions_point_attributes(&hair->pdata);
+      do_versions_point_attributes(&hair->geometry.point_data);
     }
     for (PointCloud *pointcloud = bmain->pointclouds.first; pointcloud != NULL;
          pointcloud = pointcloud->id.next) {
@@ -1424,7 +1424,7 @@ void blo_do_versions_290(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     /* Hair and PointCloud attributes names. */
     LISTBASE_FOREACH (Hair *, hair, &bmain->hairs) {
-      do_versions_point_attribute_names(&hair->pdata);
+      do_versions_point_attribute_names(&hair->geometry.point_data);
     }
     LISTBASE_FOREACH (PointCloud *, pointcloud, &bmain->pointclouds) {
       do_versions_point_attribute_names(&pointcloud->pdata);