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, 4 insertions, 4 deletions

diff --git a/source/blender/blenkernel/intern/attribute.c b/source/blender/blenkernel/intern/attribute.c
index ee8ef5e97f7..73e00398084 100644
--- a/source/blender/blenkernel/intern/attribute.c
+++ b/source/blender/blenkernel/intern/attribute.c
@@ -90,10 +90,10 @@ static void get_domains(const ID *id, DomainInfo info[ATTR_DOMAIN_NUM])
     }
     case ID_HA: {
       Hair *hair = (Hair *)id;
-      info[ATTR_DOMAIN_POINT].customdata = &hair->pdata;
-      info[ATTR_DOMAIN_POINT].length = hair->totpoint;
-      info[ATTR_DOMAIN_CURVE].customdata = &hair->cdata;
-      info[ATTR_DOMAIN_CURVE].length = hair->totcurve;
+      info[ATTR_DOMAIN_POINT].customdata = &hair->geometry.point_data;
+      info[ATTR_DOMAIN_POINT].length = hair->geometry.point_size;
+      info[ATTR_DOMAIN_CURVE].customdata = &hair->geometry.curve_data;
+      info[ATTR_DOMAIN_CURVE].length = hair->geometry.curve_size;
       break;
     }
     default: