1 files changed, 22 insertions, 0 deletions
diff --git a/source/blender/blenkernel/BKE_geometry_set.hh b/source/blender/blenkernel/BKE_geometry_set.hh
index 02b3c88183a..5b429a61b3f 100644
--- a/source/blender/blenkernel/BKE_geometry_set.hh
+++ b/source/blender/blenkernel/BKE_geometry_set.hh
@@ -467,3 +467,25 @@ class VolumeComponent : public GeometryComponent {
 
   static constexpr inline GeometryComponentType static_type = GeometryComponentType::Volume;
 };
+
+/**
+ * Used to keep track of a group of instances using the same geometry data.
+ */
+struct GeometryInstanceGroup {
+  /**
+   * The geometry set instanced on each of the transforms. The components are not necessarily
+   * owned here. For example, they may be owned by the instanced object. This cannot be a
+   * reference because not all instanced data will necessarily have a #geometry_set_eval.
+   */
+  GeometrySet geometry_set;
+
+  /**
+   * As an optimization to avoid copying, the same geometry set can be associated with multiple
+   * instances. Each instance is stored as a transform matrix here. Again, these must be owned
+   * because they may be transformed from the original data. TODO: Validate that last statement.
+   */
+  blender::Vector<blender::float4x4> transforms;
+};
+
+blender::Vector<GeometryInstanceGroup> BKE_geometry_set_gather_instances(
+    const GeometrySet &geometry_set);