Camera parameters cannot be updated and differentiate in batch

[HectorAnadon]

Hello! I report one bug and I have one question:
The bug: following the code structure of the tutorials, when updating the camera each iteration like:
cam.position = torch.tensor([0.0, 0.0, 2.5])
The change is not reflected in the rendered image.
My question: I know batch rendering is not supported, however, is it possible to differentiate over a set of rendered images? I tried to render a set over a loop and differentiate over them and got:

CUDA Runtime Error: device-side assert triggered at /home/hleon/Documents/redner/buffer.h:86
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [38,0,0], thread: [33,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [38,0,0], thread: [35,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [38,0,0], thread: [45,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [38,0,0], thread: [46,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [38,0,0], thread: [47,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [35,0,0], thread: [36,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [35,0,0], thread: [46,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [35,0,0], thread: [47,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [35,0,0], thread: [55,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [36,0,0], thread: [9,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [36,0,0], thread: [20,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [35,0,0], thread: [0,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [35,0,0], thread: [1,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [35,0,0], thread: [25,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [38,0,0], thread: [19,0,0] Assertion isfinite(nee_contrib) failed.
/home/hleon/Documents/redner/pathtracer.cpp:927: void path_contribs_accumulator::operator()(int): block: [38,0,0], thread: [20,0,0] Assertion isfinite(nee_contrib) failed.

Thank you for your help!

[BachiLi]

It's not exactly a bug, but instead of how Python and PyTorch work : p
Nevertheless I "fixed" the camera parameters in the latest commits. I am working on mini-batching and will get back to you soon.

[BachiLi]

Batching is supported now: https://colab.research.google.com/github/BachiLi/redner/blob/master/tutorials/batch_rendering.ipynb
It took me a while because I was experimenting with putting renderings in different CUDA streams. This turns out to be not worthwhile and doesn't give much performance gain.