Fix: instances are made real when they shouldn't be

The original assumption that the `modifyMesh` function is only
called when the modifier is applied was wrong. There are still a
couple of other places calling it through `BKE_modifier_modify_mesh`.

Now there is an extra check that makes sure instances are only
realized when the modifier is actually applied.

1 files changed, 5 insertions, 3 deletions

diff --git a/source/blender/modifiers/intern/MOD_nodes.cc b/source/blender/modifiers/intern/MOD_nodes.cc
index 51f9bedc0a9..9af2472f2c6 100644
--- a/source/blender/modifiers/intern/MOD_nodes.cc
+++ b/source/blender/modifiers/intern/MOD_nodes.cc
@@ -1022,9 +1022,11 @@ static Mesh *modifyMesh(ModifierData *md, const ModifierEvalContext *ctx, Mesh *
       *ctx->object);
   modifyGeometry(md, ctx, geometry_set);
 
-  /* This function is only called when applying modifiers. In this case it makes sense to realize
-   * instances, otherwise in some cases there might be no results when applying the modifier. */
-  geometry_set = blender::bke::geometry_set_realize_mesh_for_modifier(geometry_set);
+  if (ctx->flag & MOD_APPLY_TO_BASE_MESH) {
+    /* In this case it makes sense to realize instances, otherwise in some cases there might be no
+     * results when applying the modifier. */
+    geometry_set = blender::bke::geometry_set_realize_mesh_for_modifier(geometry_set);
+  }
 
   Mesh *new_mesh = geometry_set.get_component_for_write<MeshComponent>().release();
   if (new_mesh == nullptr) {