usd_reader_shape.hh

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/* SPDX-FileCopyrightText: 2023 Nvidia. All rights reserved.
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#pragma once
 
#include "usd.hh"
#include "usd_hash_types.hh"
#include "usd_reader_geom.hh"
 
struct Mesh;
 
namespace blender::io::usd {
 
/*
 * Read USDGeom primitive shapes as Blender Meshes.  This class uses the same adapter functions
 * as the GL viewport to generate geometry for each of the supported types.
 */
class USDShapeReader : public USDGeomReader {
  /* A cache to record whether a given primvar is time-varying, so that static primvars are not
   * read more than once when the mesh is evaluated for animation by the cache file modifier.
   * The map is mutable so that it can be updated in const functions. */
  mutable blender::Map<const pxr::TfToken, bool> primvar_time_varying_map_;
 
 private:
  /* Template required to read mesh information out of Shape prims,
   * as each prim type has a separate subclass. */
  template<typename Adapter>
  void read_values(pxr::UsdTimeCode time,
                   pxr::VtVec3fArray &positions,
                   pxr::VtIntArray &face_indices,
                   pxr::VtIntArray &face_counts) const;
 
  /* Wrapper for the templated method read_values, calling the correct template
   * instantiation based on the introspected prim type. */
  bool read_mesh_values(pxr::UsdTimeCode time,
                        pxr::VtVec3fArray &positions,
                        pxr::VtIntArray &face_indices,
                        pxr::VtIntArray &face_counts) const;
 
  void apply_primvars_to_mesh(Mesh *mesh, pxr::UsdTimeCode time) const;
 
  /* Read the pxr:UsdGeomMesh values and convert them to a Blender Mesh,
   * also returning face_indices and counts for further loop processing. */
  Mesh *mesh_from_prim(Mesh *existing_mesh,
                       USDMeshReadParams params,
                       pxr::VtIntArray &face_indices,
                       pxr::VtIntArray &face_counts) const;
 
  Mesh *read_mesh(Mesh *existing_mesh, USDMeshReadParams params, const char ** /*r_err_str*/);
 
 public:
  USDShapeReader(const pxr::UsdPrim &prim,
                 const USDImportParams &import_params,
                 const ImportSettings &settings);
 
  void create_object(Main *bmain) override;
  void read_object_data(Main *bmain, pxr::UsdTimeCode time) override;
  void read_geometry(bke::GeometrySet & /*geometry_set*/,
                     USDMeshReadParams /*params*/,
                     const char ** /*r_err_str*/) override;
 
  /* Returns the generated mesh might be affected by time-varying attributes.
   * This assumes mesh_from_prim() has been called. */
  bool is_time_varying();
 
  bool topology_changed(const Mesh * /*existing_mesh*/, pxr::UsdTimeCode /*time*/) override
  {
    return false;
  };
};
 
}  // namespace blender::io::usd