Fix T91767: crash when instancing geometry coming from modifier

The issue was that the `GeometrySet` that comes from the modifier does
not have full ownership of the mesh for legacy reasons to avoid copies.
Calling `ensure_owns_direct_data` makes sure that the geometry set
actually owns the geometry so that it can be instanced.

1 files changed, 9 insertions, 6 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_instance_on_points.cc b/source/blender/nodes/geometry/nodes/node_geo_instance_on_points.cc
index 490535224c8..8c0c0763be8 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_instance_on_points.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_instance_on_points.cc
@@ -57,10 +57,9 @@ static void geo_node_instance_on_points_declare(NodeDeclarationBuilder &b)
 
 static void add_instances_from_component(InstancesComponent &dst_component,
                                          const GeometryComponent &src_component,
+                                         const GeometrySet &instance,
                                          const GeoNodeExecParams &params)
 {
-  GeometrySet instance = params.get_input<GeometrySet>("Instance");
-
   const AttributeDomain domain = ATTR_DOMAIN_POINT;
   const int domain_size = src_component.attribute_domain_size(domain);
 
@@ -163,23 +162,27 @@ static void add_instances_from_component(InstancesComponent &dst_component,
 static void geo_node_instance_on_points_exec(GeoNodeExecParams params)
 {
   GeometrySet geometry_set = params.extract_input<GeometrySet>("Points");
+  GeometrySet instance = params.get_input<GeometrySet>("Instance");
+  instance.ensure_owns_direct_data();
 
   geometry_set.modify_geometry_sets([&](GeometrySet &geometry_set) {
     InstancesComponent &instances = geometry_set.get_component_for_write<InstancesComponent>();
 
     if (geometry_set.has<MeshComponent>()) {
       add_instances_from_component(
-          instances, *geometry_set.get_component_for_read<MeshComponent>(), params);
+          instances, *geometry_set.get_component_for_read<MeshComponent>(), instance, params);
       geometry_set.remove(GEO_COMPONENT_TYPE_MESH);
     }
     if (geometry_set.has<PointCloudComponent>()) {
-      add_instances_from_component(
-          instances, *geometry_set.get_component_for_read<PointCloudComponent>(), params);
+      add_instances_from_component(instances,
+                                   *geometry_set.get_component_for_read<PointCloudComponent>(),
+                                   instance,
+                                   params);
       geometry_set.remove(GEO_COMPONENT_TYPE_POINT_CLOUD);
     }
     if (geometry_set.has<CurveComponent>()) {
       add_instances_from_component(
-          instances, *geometry_set.get_component_for_read<CurveComponent>(), params);
+          instances, *geometry_set.get_component_for_read<CurveComponent>(), instance, params);
       geometry_set.remove(GEO_COMPONENT_TYPE_CURVE);
     }
     /* Unused references may have been added above. Remove those now so that other nodes don't