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diff --git a/intern/cycles/render/alembic_read.h b/intern/cycles/render/alembic_read.h
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+++ b/intern/cycles/render/alembic_read.h
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+/*
+ * Copyright 2021 Blender Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#ifdef WITH_ALEMBIC
+
+#  include <Alembic/AbcCoreFactory/All.h>
+#  include <Alembic/AbcGeom/All.h>
+
+#  include "util/util_vector.h"
+
+CCL_NAMESPACE_BEGIN
+
+class AlembicProcedural;
+class AttributeRequestSet;
+class Progress;
+struct CachedData;
+
+/* Maps a FaceSet whose name matches that of a Shader to the index of said shader in the Geometry's
+ * used_shaders list. */
+struct FaceSetShaderIndexPair {
+  Alembic::AbcGeom::IFaceSet face_set;
+  int shader_index;
+};
+
+/* Data of an IPolyMeshSchema that we need to read. */
+struct PolyMeshSchemaData {
+  Alembic::AbcGeom::TimeSamplingPtr time_sampling;
+  size_t num_samples;
+  Alembic::AbcGeom::MeshTopologyVariance topology_variance;
+
+  Alembic::AbcGeom::IP3fArrayProperty positions;
+  Alembic::AbcGeom::IInt32ArrayProperty face_indices;
+  Alembic::AbcGeom::IInt32ArrayProperty face_counts;
+
+  Alembic::AbcGeom::IN3fGeomParam normals;
+
+  vector<FaceSetShaderIndexPair> shader_face_sets;
+
+  // Unsupported for now.
+  Alembic::AbcGeom::IV3fArrayProperty velocities;
+};
+
+void read_geometry_data(AlembicProcedural *proc,
+                        CachedData &cached_data,
+                        const PolyMeshSchemaData &data,
+                        Progress &progress);
+
+/* Data of an ISubDSchema that we need to read. */
+struct SubDSchemaData {
+  Alembic::AbcGeom::TimeSamplingPtr time_sampling;
+  size_t num_samples;
+  Alembic::AbcGeom::MeshTopologyVariance topology_variance;
+
+  Alembic::AbcGeom::IInt32ArrayProperty face_counts;
+  Alembic::AbcGeom::IInt32ArrayProperty face_indices;
+  Alembic::AbcGeom::IP3fArrayProperty positions;
+
+  Alembic::AbcGeom::IInt32ArrayProperty crease_indices;
+  Alembic::AbcGeom::IInt32ArrayProperty crease_lengths;
+  Alembic::AbcGeom::IFloatArrayProperty crease_sharpnesses;
+
+  vector<FaceSetShaderIndexPair> shader_face_sets;
+
+  // Those are unsupported for now.
+  Alembic::AbcGeom::IInt32ArrayProperty corner_indices;
+  Alembic::AbcGeom::IFloatArrayProperty corner_sharpnesses;
+  Alembic::AbcGeom::IInt32Property face_varying_interpolate_boundary;
+  Alembic::AbcGeom::IInt32Property face_varying_propagate_corners;
+  Alembic::AbcGeom::IInt32Property interpolate_boundary;
+  Alembic::AbcGeom::IInt32ArrayProperty holes;
+  Alembic::AbcGeom::IStringProperty subdivision_scheme;
+  Alembic::AbcGeom::IV3fArrayProperty velocities;
+};
+
+void read_geometry_data(AlembicProcedural *proc,
+                        CachedData &cached_data,
+                        const SubDSchemaData &data,
+                        Progress &progress);
+
+/* Data of a ICurvesSchema that we need to read. */
+struct CurvesSchemaData {
+  Alembic::AbcGeom::TimeSamplingPtr time_sampling;
+  size_t num_samples;
+  Alembic::AbcGeom::MeshTopologyVariance topology_variance;
+
+  Alembic::AbcGeom::IP3fArrayProperty positions;
+
+  Alembic::AbcGeom::IInt32ArrayProperty num_vertices;
+
+  float default_radius;
+  float radius_scale;
+
+  // Those are unsupported for now.
+  Alembic::AbcGeom::IV3fArrayProperty velocities;
+  // if this property is invalid then the weight for every point is 1
+  Alembic::AbcGeom::IFloatArrayProperty position_weights;
+  Alembic::AbcGeom::IN3fGeomParam normals;
+  Alembic::AbcGeom::IFloatGeomParam widths;
+  Alembic::AbcGeom::IUcharArrayProperty orders;
+  Alembic::AbcGeom::IFloatArrayProperty knots;
+
+  // TODO(@kevindietrich): type, basis, wrap
+};
+
+void read_geometry_data(AlembicProcedural *proc,
+                        CachedData &cached_data,
+                        const CurvesSchemaData &data,
+                        Progress &progress);
+
+void read_attributes(AlembicProcedural *proc,
+                     CachedData &cache,
+                     const Alembic::AbcGeom::ICompoundProperty &arb_geom_params,
+                     const Alembic::AbcGeom::IV2fGeomParam &default_uvs_param,
+                     const AttributeRequestSet &requested_attributes,
+                     Progress &progress);
+
+CCL_NAMESPACE_END
+
+#endif