Curves: support sculpting on deformed curves

Previously, curves sculpt tools only worked on original data. This was
very limiting, because one could effectively only sculpt the curves when
all procedural effects were turned off. This patch adds support for curves
sculpting while looking the result of procedural effects (like deformation
based on the surface mesh). This functionality is also known as "crazy space"
support in Blender.

For more details see D15407.

Differential Revision: https://developer.blender.org/D15407

1 files changed, 15 insertions, 2 deletions

diff --git a/source/blender/geometry/intern/realize_instances.cc b/source/blender/geometry/intern/realize_instances.cc
index 0544f304283..4b3b184536b 100644
--- a/source/blender/geometry/intern/realize_instances.cc
+++ b/source/blender/geometry/intern/realize_instances.cc
@@ -204,7 +204,8 @@ struct GatherTasks {
 
   /* Volumes only have very simple support currently. Only the first found volume is put into the
    * output. */
-  UserCounter<VolumeComponent> first_volume;
+  UserCounter<const VolumeComponent> first_volume;
+  UserCounter<const GeometryComponentEditData> first_edit_data;
 };
 
 /** Current offsets while during the gather operation. */
@@ -582,7 +583,16 @@ static void gather_realize_tasks_recursive(GatherTasksInfo &gather_info,
         const VolumeComponent *volume_component = static_cast<const VolumeComponent *>(component);
         if (!gather_info.r_tasks.first_volume) {
           volume_component->user_add();
-          gather_info.r_tasks.first_volume = const_cast<VolumeComponent *>(volume_component);
+          gather_info.r_tasks.first_volume = volume_component;
+        }
+        break;
+      }
+      case GEO_COMPONENT_TYPE_EDIT: {
+        const GeometryComponentEditData *edit_component =
+            static_cast<const GeometryComponentEditData *>(component);
+        if (!gather_info.r_tasks.first_edit_data) {
+          edit_component->user_add();
+          gather_info.r_tasks.first_edit_data = edit_component;
         }
         break;
       }
@@ -1405,6 +1415,9 @@ GeometrySet realize_instances(GeometrySet geometry_set, const RealizeInstancesOp
   if (gather_info.r_tasks.first_volume) {
     new_geometry_set.add(*gather_info.r_tasks.first_volume);
   }
+  if (gather_info.r_tasks.first_edit_data) {
+    new_geometry_set.add(*gather_info.r_tasks.first_edit_data);
+  }
 
   return new_geometry_set;
 }