pip install submodules/diff-gaussian-rasterization with CUDA_HOME error

[XuanyuZhang]

Thanks for release this impressive work.

When I run the "pip install submodules/diff-gaussian-rasterization", I met a strange error "OSError: CUDA_HOME environment variable is not set. Please set it to your CUDA install root.".

However, when I use the "echo $CUDA_HOME" under the same enviroment, system will print the right path.

Thank you for your help.