KiRaRay is a simple interactive ray-tracing renderer using optix.

Working in progress (?) project
This toy renderer is purposed for learning and only with limited features.

• GPU path tracing (megakernel/wavefront).
• GPU volumetric rendering (wavefront).
• Spectral or tristimulus (RGB) rendering.
• Other distributed effects like DoF and motion blur.
• Post processing passes (e.g. denoising).
• Single/multi-level scene graph with animation support.
• Interactive editing scene components with simple UI.

Windows (MSVC)

• Nvidia RTX GPU (Turing or higher).
• OptiX 7.3+ and CUDA 11.4+.
• Vulkan SDK 1.3+.

This project is developed with on Windows (MSVC). It cannot compile on Linux.

KiRaRay now uses Vulkan for better interoperability with CUDA, and extensibility to rasterization-based render passes. If Vulkan is not desired, check the legacy-GL branch that instead depends on OpenGL.

KiRaRay uses thirdparty dependencies as submodules so fetch them recursively when cloning:

git clone --recursive https://github.com/cuteday/KiRaRay.git

This project uses cmake to build, make sure CUDA is installed and added to PATH. Several optional variables are available for building configuration.

Specify the json configuration file as command line argument to start the renderer, as the example below. Check the example configurations for some test scenes, showcasing core features like volumetric rendering, animated scenes and motion blur.

build/src/kiraray.exe common/configs/example_cbox.json

The two necessary entries in the configuration are model (specifying the relative path to the scene file) and passes (describing the render pipeline). Once compiled, directly run kiraray without specifying configuration (this example configuration will be used) to get a feel for this toy renderer.

Camera controlling. Dragging LeftMouse for orbiting, dragging Scroll or Shift+LeftMouse for panning. Scroll for zooming in/out.

Python binding. Several simple interfaces are exposed to python scripting via pybind11, including a OptiX denoiser wrapper for denoising NumPy or PyTorch tensors, see scripts for details.

It is possible to write your own render pass, see the examples here. Check bindless render pass (rasterization) or the post-processing passes for more working examples.

Kiraray provided limited support for importing scenes like OBJ, glTF2 using Assimp. Animations in glTF2 models could be correctly imported, but skeleton animation is not yet supported. pbrt-parser is used to import pbrt-v3 scenes (get some here, modify the file url to download the pbrt-v3 format models).

• The great optix tutorial for beginners: optix7course.
• Some of the code are adapted from pbrt and donut.
• KiRaRay has a tiny math wrapper built upon eigen.
• ImGui is used to build simple user interfaces for this project.