draco/io/obj_encoder.cc

// Copyright 2016 The Draco Authors.
//
// 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.
//
#include "io/obj_encoder.h"

#include <fstream>

namespace draco {

ObjEncoder::ObjEncoder()
    : pos_att_(nullptr),
      tex_coord_att_(nullptr),
      normal_att_(nullptr),
      out_buffer_(nullptr),
      in_point_cloud_(nullptr),
      in_mesh_(nullptr) {}

bool ObjEncoder::EncodeToFile(const PointCloud &pc,
                              const std::string &file_name) {
  std::ofstream file(file_name);
  if (!file)
    return false;  // File could not be opened.
  // Encode the mesh into a buffer.
  EncoderBuffer buffer;
  if (!EncodeToBuffer(pc, &buffer))
    return false;
  // Write the buffer into the file.
  file.write(buffer.data(), buffer.size());
  return true;
}

bool ObjEncoder::EncodeToFile(const Mesh &mesh, const std::string &file_name) {
  in_mesh_ = &mesh;
  return EncodeToFile(static_cast<const PointCloud &>(mesh), file_name);
}

bool ObjEncoder::EncodeToBuffer(const PointCloud &pc,
                                EncoderBuffer *out_buffer) {
  in_point_cloud_ = &pc;
  out_buffer_ = out_buffer;
  if (!EncodeInternal())
    return ExitAndCleanup(false);
  return ExitAndCleanup(true);
}

bool ObjEncoder::EncodeToBuffer(const Mesh &mesh, EncoderBuffer *out_buffer) {
  in_mesh_ = &mesh;
  return EncodeToBuffer(static_cast<const PointCloud &>(mesh), out_buffer);
}

bool ObjEncoder::EncodeInternal() {
  pos_att_ = nullptr;
  tex_coord_att_ = nullptr;
  normal_att_ = nullptr;
  if (!EncodePositions())
    return false;
  if (!EncodeTextureCoordinates())
    return false;
  if (!EncodeNormals())
    return false;
  if (in_mesh_ && !EncodeFaces())
    return false;
  return true;
}

bool ObjEncoder::ExitAndCleanup(bool return_value) {
  in_mesh_ = nullptr;
  in_point_cloud_ = nullptr;
  out_buffer_ = nullptr;
  pos_att_ = nullptr;
  tex_coord_att_ = nullptr;
  normal_att_ = nullptr;
  return return_value;
}

bool ObjEncoder::EncodePositions() {
  const PointAttribute *const att =
      in_point_cloud_->GetNamedAttribute(GeometryAttribute::POSITION);
  if (att == nullptr || att->size() == 0)
    return false;  // Position attribute must be valid.
  std::array<float, 3> value;
  for (AttributeValueIndex i(0); i < att->size(); ++i) {
    if (!att->ConvertValue<float, 3>(i, &value[0]))
      return false;
    buffer()->Encode("v ", 2);
    EncodeFloatList(&value[0], 3);
    buffer()->Encode("\n", 1);
  }
  pos_att_ = att;
  return true;
}

bool ObjEncoder::EncodeTextureCoordinates() {
  const PointAttribute *const att =
      in_point_cloud_->GetNamedAttribute(GeometryAttribute::TEX_COORD);
  if (att == nullptr || att->size() == 0)
    return true;  // It's ok if we don't have texture coordinates.
  std::array<float, 2> value;
  for (AttributeValueIndex i(0); i < att->size(); ++i) {
    if (!att->ConvertValue<float, 2>(i, &value[0]))
      return false;
    buffer()->Encode("vt ", 3);
    EncodeFloatList(&value[0], 2);
    buffer()->Encode("\n", 1);
  }
  tex_coord_att_ = att;
  return true;
}

bool ObjEncoder::EncodeNormals() {
  const PointAttribute *const att =
      in_point_cloud_->GetNamedAttribute(GeometryAttribute::NORMAL);
  if (att == nullptr || att->size() == 0)
    return true;  // It's ok if we don't have normals.
  std::array<float, 3> value;
  for (AttributeValueIndex i(0); i < att->size(); ++i) {
    if (!att->ConvertValue<float, 3>(i, &value[0]))
      return false;
    buffer()->Encode("vn ", 3);
    EncodeFloatList(&value[0], 3);
    buffer()->Encode("\n", 1);
  }
  normal_att_ = att;
  return true;
}

bool ObjEncoder::EncodeFaces() {
  for (FaceIndex i(0); i < in_mesh_->num_faces(); ++i) {
    buffer()->Encode('f');
    for (int j = 0; j < 3; ++j) {
      if (!EncodeFaceCorner(i, j))
        return false;
    }
    buffer()->Encode("\n", 1);
  }
  return true;
}

bool ObjEncoder::EncodeFaceCorner(FaceIndex face_id, int local_corner_id) {
  buffer()->Encode(' ');
  const PointIndex vert_index = in_mesh_->face(face_id)[local_corner_id];
  // Note that in the OBJ format, all indices are encoded starting from index 1.
  // Encode position index.
  EncodeInt(pos_att_->mapped_index(vert_index).value() + 1);
  if (tex_coord_att_ || normal_att_) {
    // Encoding format is pos_index/tex_coord_index/normal_index.
    // If tex_coords are not present, we must encode pos_index//normal_index.
    buffer()->Encode('/');
    if (tex_coord_att_) {
      EncodeInt(tex_coord_att_->mapped_index(vert_index).value() + 1);
    }
    if (normal_att_) {
      buffer()->Encode('/');
      EncodeInt(normal_att_->mapped_index(vert_index).value() + 1);
    }
  }
  return true;
}

void ObjEncoder::EncodeFloat(float val) {
  snprintf(num_buffer_, sizeof(num_buffer_), "%f", val);
  buffer()->Encode(num_buffer_, strlen(num_buffer_));
}

void ObjEncoder::EncodeFloatList(float *vals, int num_vals) {
  for (int i = 0; i < num_vals; ++i) {
    if (i > 0) {
      buffer()->Encode(' ');
    }
    EncodeFloat(vals[i]);
  }
}

void ObjEncoder::EncodeInt(int32_t val) {
  snprintf(num_buffer_, sizeof(num_buffer_), "%d", val);
  buffer()->Encode(num_buffer_, strlen(num_buffer_));
}

}  // namespace draco