read_obj.h

#pragma once

#include <memory>
#include <string>
#include <tuple>
#include <vector>

#include <Eigen/Core>

namespace drake {
namespace geometry {
namespace internal {
/** Reads the OBJ file with the given `filename` into a collection of data. It
 * includes the vertex positions, face encodings (see TinyObjToFclFaces), and
 * number of faces.
 * @param filename The name of the obj file.
 * @param scale Scale to coordinates.
 * @param triangulate Whether triangulate polygon face in .obj or not. Refer to
 * LoadObj function in
 * https://github.com/tinyobjloader/tinyobjloader/blob/master/tiny_obj_loader.h
 * for more details.
 * @return (vertices, faces, num_faces) vertices[i] is the i'th vertex in the
 * mesh. faces is interpreted as
 *
 * faces = { n0, v0_0,v0_1,...,v0_n0-1,
 *           n1, v1_0,v1_1,...,v1_n1-1,
 *           n2, v2_0,v2_1,...,v2_n2-1,
 *           ...}
 *
 * where n_i is the number of vertices of face_i, vi_j is the index in
 * `vertices` for a vertex on face i. Note that the size of faces is larger than
 * num_faces.
 *
 */
std::tuple<std::shared_ptr<std::vector<Eigen::Vector3d>>,
           std::shared_ptr<std::vector<int>>, int>
ReadObjFile(const std::string& filename, double scale, bool triangulate);

}  // namespace internal
}  // namespace geometry
}  // namespace drake