关于如何扩展到下一个节点的坐标计算问题

[fantasyplus]

Node3D* Node3D::createSuccessor(const int i) {
  float xSucc;
  float ySucc;
  float tSucc;

  // calculate successor p ositions forward
  if (i < 3) {//前向 Successor
    xSucc = x + dx[i] * cos(t) - dy[i] * sin(t);
    ySucc = y + dx[i] * sin(t) + dy[i] * cos(t);
    tSucc = Helper::normalizeHeadingRad(t + dt[i]);
  }
  // backwards
  else {//后向 Successor
    xSucc = x - dx[i - 3] * cos(t) - dy[i - 3] * sin(t);
    ySucc = y - dx[i - 3] * sin(t) + dy[i - 3] * cos(t);
    tSucc = Helper::normalizeHeadingRad(t - dt[i - 3]);
  }

  return new Node3D(xSucc, ySucc, tSucc, g, 0, this, i);
}

请问这里的dx，dy是小车坐标系吗，还是平面坐标系，我算了好久硬是没算出来这个坐标是怎么计算的。。

[LadissonLai]

dx和dy为小车坐标系，作者给了三个扩展数量，前进，左转，右转，三种扩展方式的路径长度是一样的。

[LadissonLai]

Node3D* Node3D::createSuccessor(const int i) {
  float xSucc;
  float ySucc;
  float tSucc;

  // calculate successor p ositions forward
  if (i < 3) {//前向 Successor
    xSucc = x + dx[i] * cos(t) - dy[i] * sin(t);
    ySucc = y + dx[i] * sin(t) + dy[i] * cos(t);
    tSucc = Helper::normalizeHeadingRad(t + dt[i]);
  }
  // backwards
  else {//后向 Successor
    xSucc = x - dx[i - 3] * cos(t) - dy[i - 3] * sin(t);
    ySucc = y - dx[i - 3] * sin(t) + dy[i - 3] * cos(t);
    tSucc = Helper::normalizeHeadingRad(t - dt[i - 3]);
  }

  return new Node3D(xSucc, ySucc, tSucc, g, 0, this, i);
}

请问这里的dx，dy是小车坐标系吗，还是平面坐标系，我算了好久硬是没算出来这个坐标是怎么计算的。。

请参考#3 (comment)