TorchOptiX

Modular wrapper for using OptiX with PyTorch.

Requirements

Most requirements are the same as running OptiX.

• Hardware: All NVIDIA GPUs of Compute Capability 5.0 (Maxwell) or higher are supported.
• Driver: An driver version of R515+ is required. You may check with nvidia-smi.
• Python: 3.8 or higher.
• PyTorch: 2 or higher is recommended. May also work for older versions.

Running in containers like Docker

To run inside a container, you need to configure the driver for OptiX. You can choose from the following options:

1. Set ENV NVIDIA_DRIVER_CAPABILITIES compute,utility,graphics and ENV PYOPENGL_PLATFORM egl in Dockerfile when building the image.
2. Set -e NVIDIA_DRIVER_CAPABILITIES=graphics,compute,utility when creating the container.
3. Copy or mount /usr/lib/x86_64-linux-gnu/libnvoptix.so.<version> on the host or download a same version of the library to /usr/lib/x86_64-linux-gnu/libnvoptix.so.1 in the container; copy /usr/lib/x86_64-linux-gnu/libnvidia-rtcore.so.<version> on the host or download a same version of the library to /usr/lib/x86_64-linux-gnu/libnvidia-rtcore.so.<version> in the container.

Installation

Stable release (Windows or Linux 64-bit):

pip install torchoptix

The wheel contains prebuilt binaries, and you do not need CUDA development toolkit to run the code.

Development (or if you are not using a common system supported by prebuilt binaries):

pip install git+https://github.com/eliphatfs/torchoptix.git

You will need to have CUDA_HOME set to compile or develop. The code does not depend on CUDA runtime libraries or nvcc, but needs CUDA driver API header and link libraries.

To regenerate resources for device code if you modified it in development:

bash generate.sh

Usage

Example Wrapper

import torch
from typing import Tuple

class TorchOptiX:
    @torch.no_grad()
    def __init__(self, verts: torch.Tensor, tris: torch.IntTensor) -> None:
        self.handle = None
        import torchoptix
        self.optix = torchoptix
        self.verts = verts.contiguous()
        self.tris = tris.contiguous()
        self.handle = self.optix.build(
            self.verts.data_ptr(), self.tris.data_ptr(),
            len(verts), len(tris)
        )

    @torch.no_grad()
    def query(self, rays_o: torch.Tensor, rays_d: torch.Tensor, far: float) -> Tuple[torch.Tensor]:
        # out_i starts at 0 and is 0 when not hit.
        # you can decide hits via `t < far`.
        out_t = rays_o.new_empty([len(rays_o)])
        out_i = rays_o.new_empty([len(rays_o)], dtype=torch.int32)
        rays_o = rays_o.contiguous()
        rays_d = rays_d.contiguous()
        self.optix.trace_rays(
            self.handle,
            rays_o.data_ptr(),
            rays_d.data_ptr(),
            out_t.data_ptr(), out_i.data_ptr(),
            far, len(rays_o)
        )
        return out_t, out_i

    def __del__(self):
        if self.handle is not None and self.optix is not None and self.optix.release is not None:
            self.optix.release(self.handle)
            self.handle = None

Example:

import torch.nn.functional as F
accel = TorchOptiX(torch.randn(10, 3).cuda(), torch.randint(0, 10, [5, 3]).cuda().int())
t, i = accel.query(torch.randn(20, 3).cuda(), F.normalize(torch.randn(20, 3).cuda(), dim=-1), far=32767)
print(t, i, sep='\n')

Low-level API

NAME
    torchoptix - Modular OptiX ray tracing functions interop with PyTorch.

FUNCTIONS
    build(...)
        build(verts, tris, n_verts, n_tris) -> handle

        Build OptiX acceleration structure.

    release(...)
        release(handle)

        Release OptiX acceleration structure.

    set_log_level(...)
        set_log_level(level)

        Set OptiX log level (0-4).

    trace_rays(...)
        trace_rays(handle, rays_o, rays_d, out_t, out_i, t_max, n_rays)

        Trace rays with OptiX.

verts, tris, rays_o, rays_d, out_t, out_i are CUDA device pointers. tris and out_i are contiguous int32 arrays, and others are float32 arrays. t_max (float) is maximum distance of ray to trace.

The functions need to be called when the same CUDA device context is active. The APIs are not thread-safe on the same device. In PyTorch, to run on multiple devices you need to use distributed parallelism, and each process runs a device. Multi-threading on devices is not supported.

It is not necessary that the arrays originate from PyTorch. It can be allocated with native CUDA.

Citation

@misc{TorchOptiX,
  title = {TorchOptiX},
  howpublished = {\url{https://github.com/eliphatfs/torchoptix}},
  note = {Accessed: 2024-09-13}
}