Force ninja for installation (issue #208)

README.md

@@ -56,6 +56,7 @@ We visualized a sparse tensor network operation on a sparse tensor, convolution,
 - CUDA >= 10.1.243 and **the same CUDA version used for pytorch** (e.g. if you use conda cudatoolkit=11.1, use CUDA=11.1 for MinkowskiEngine compilation)
 - pytorch >= 1.7 (if you use conda, install with `conda install -y -c conda-forge -c pytorch pytorch=1.8.1 cudatoolkit=11.1`)
 - python >= 3.6
+- ninja (for installation)
 - GCC >= 7
 
 
@@ -75,7 +76,7 @@ First, install pytorch following the [instruction](https://pytorch.org). Next, i
 
 ```
 sudo apt install build-essential python3-dev libopenblas-dev
-pip install torch
+pip install torch ninja
 pip install -U MinkowskiEngine --install-option="--blas=openblas" -v --no-deps
 
 # For pip installation from the latest source
@@ -130,7 +131,7 @@ sudo apt install build-essential python3-dev libopenblas-dev
 curl https://bootstrap.pypa.io/get-pip.py | python3
 
 # Get pip and install python requirements
-python3 -m pip install torch numpy
+python3 -m pip install torch numpy ninja
 
 git clone https://github.com/NVIDIA/MinkowskiEngine.git
 

setup.py

@@ -265,7 +265,6 @@ def _argparse(pattern, argv, is_flag=True, is_list=False):
 
 debug, argv = _argparse("--debug", argv)
 
-USE_NINJA = os.getenv("USE_NINJA") == "0"
 HERE = Path(os.path.dirname(__file__)).absolute()
 SRC_PATH = HERE / "src"
 
@@ -320,7 +319,7 @@ def _argparse(pattern, argv, is_flag=True, is_list=False):
     package_dir={"MinkowskiEngine": "./MinkowskiEngine"},
     ext_modules=ext_modules,
     include_dirs=[str(SRC_PATH), str(SRC_PATH / "3rdparty"), *include_dirs],
-    cmdclass={"build_ext": BuildExtension},
+    cmdclass={"build_ext": BuildExtension.with_options(use_ninja=True)},
     author="Christopher Choy",
     author_email="chrischoy@ai.stanford.edu",
     description="a convolutional neural network library for sparse tensors",