iPERCore: "Failed to build neural-renderer"

Hi, iPERDance team! I really appreciate your great work! I met some problems when running the command “python setup.py develop” :

Building wheel for neural-renderer (setup.py) ... error
  ERROR: Command errored out with exit status 1:
   command: /home/ang/anaconda3/envs/iPERDance/bin/python -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-req-build-1b_3r1yg/setup.py'"'"'; __file__='"'"'/tmp/pip-req-build-1b_3r1yg/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' bdist_wheel -d /tmp/pip-wheel-be6hts_5
       cwd: /tmp/pip-req-build-1b_3r1yg/
  Complete output (334 lines):
  running bdist_wheel
  /home/ang/anaconda3/envs/iPERDance/lib/python3.6/site-packages/torch/utils/cpp_extension.py:339: UserWarning: Attempted to use ninja as the BuildExtension backend but we could not find ninja.. Falling back to using the slow distutils backend.
    warnings.warn(msg.format('we could not find ninja.'))
...

(My environment: ubuntu16.04, cuda10.1, gcc/g++7.5.0, anaconda python3.6.6, and I did activate conda env when I running the command)

I have tried several times to run the command but I met the same error. Hope your advice! Thanks in advance~